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The apophysis is a secondary ossification center found on non-weight-bearing segments of bones. It is the site of ligament or tendon insertion and is involved in the peripheral growth of bones. These secondary growth centers are generally open during childhood and do not close until early adulthood. Chronic apophyseal injury (traction apophysitis) almost always happens in adolescent athletes during periods of growth. Types of chronic apophyseal injury include Sever disease (posterior calcaneal apophysitis), Osgood-Schlatter disease (tibial tuberosity apophysitis), little league elbow (medial epicondyle apophysitis), and Sinding-Larsen-Johansson syndrome (inferior patella apophysitis). Diagnosis is generally made clinically. Chronic apophyseal injuries are generally treated with a conservative approach and rarely require surgical intervention.
Invasive mechanical ventilation (IMV) is an advanced airway modality used for individuals with immediate or impending respiratory failure and/or in preparation for surgery. The IMV technique involves positive pressure ventilation delivered to the lungs through an endotracheal tube via a ventilator. The ventilator can be set to specific modes that determine how the machine assists with breathing. The modes are tailored to the individual's needs. The mode refers to the characteristics of mechanical ventilation and mainly includes trigger (how inspiration begins), cycle (how inspiration ends), and limit (when inspiration should be aborted). The most commonly used mode is assist-control ventilation, which is usually followed by pressure-support ventilation for weaning. Careful consideration should be exercised while planning extubation, as IMV is associated with complications.
Imaging of the intestines is typically performed utilizing a multimodal approach, with clinical suspicion being the primary indicator for which study should be completed and in what order. There are also many differences between outpatient imaging versus emergency or inpatient imaging of the intestines. Imaging varies widely based on the patient's history, symptoms, and physical exam findings. The patient's age will also play a factor in the modality chosen. For example, appendicitis is typically 1st evaluated via ultrasound in the pediatric population versus CT in adults.
Surgical complications are conditions, disorders, or adverse events that occur following surgical procedures. The most common general surgical complications include bleeding, infections, injury to the surrounding organs, venous thromboembolic events, and complications from anesthesia. In addition, patients may also experience a variety of cardiac, pulmonary, renal/urologic, and CNS complications, especially if the patient is elderly and/or has underlying medical comorbidities. The clinician should be aware of all of these potential complications and their presenting symptoms in order to quickly identify and treat them. Some of the most common signs and symptoms suggestive of a potential complication include tachycardia, hypoxia, fever, pain, and mental status changes.
Congenital infections are acquired in utero or during passage through the birth canal at birth and can be associated with significant morbidity and mortality for the infant. The TORCH infections are a group of congenital infections grouped due to their similar presentation. The acronym TORCH arises from the names of the infectious agents that cause the diseases included in this group: toxoplasmosis, other agents (syphilis, varicella zoster virus (VZV), parvovirus B19, and HIV), rubella, CMV, and herpes simplex.
The primary goals of antepartum testing and monitoring are to assess fetal well-being, identify treatable situations that may cause complications, and evaluate for chromosomal abnormalities. Antepartum tests for aneuploidy are typically performed in the 1st and 2nd trimesters. These tests are divided into screening tests (which include cell-free DNA testing, serum analyte testing, and nuchal translucency measurements), and diagnostic tests, which provide a definitive diagnosis of aneuploidy and include chorionic villus sampling (CVS) and amniocentesis. Antepartum monitoring is done in the 2nd and 3rd trimesters to evaluate fetal well-being and assess the risk of fetal death. Antepartum monitoring tests include continuous cardiotocography (i.e., fetal heart rate tracings), the non-stress and contraction stress tests (NST and CST, respectively), the fetal biophysical profile (BPP), and umbilical artery Doppler studies.
Cancer immunotherapy is a rapidly advancing medical therapy that takes advantage of the immune system to contain or eliminate cancer cells. Currently, immunotherapies have been incorporated into treatment regimens for different types of cancer. Various therapeutic approaches exist, including using cytokines, vaccines, oncolytic viruses, T-cell manipulation or cellular adoptive immunotherapy, or antibodies to immune checkpoint molecules. These therapies provide new options for advanced cancers, including melanoma, renal cell carcinoma, prostate adenocarcinoma, lung cancer, urothelial carcinoma, Hodgkin lymphoma, and refractory B-cell ALL. With the immune system involved, these agents carry serious and potentially fulminant adverse effects and toxicities.
The prenatal period begins with the formation of the embryo and continues through the development of the fetus, terminating with birth. Neonatal physiology during prenatal life differs significantly from that during postnatal life. Before birth, nutrient, gas exchange, and elimination of waste products occur via the placenta. The fetus receives oxygenated blood via the umbilical vein, and deoxygenated blood is removed via the umbilical arteries. The 3 shunts that help redirect the fetal circulation are the ductus venosus, foramen ovale, and ductus arteriosus. These shunts close after birth, leaving behind vestigial remnants. Postnatally, the fetal circulatory system and organ systems adapt to the extrauterine environment. Placental blood supply is cut off, causing the neonate to make adaptive changes.
Estrogen and progesterone are the sex hormones produced by the ovaries in premenopausal women. These agents are responsible for developing and maintaining female sex organs and secondary sexual characteristics. Estrogen and progesterone are used to treat hypogonadism (primary ovarian insufficiency), menopausal symptoms, and gender dysphoria in transgender women. Risks and side effects include uterine bleeding, predisposition to cancer, breast tenderness, hyperpigmentation, migraines, hypertension, and mood changes. Contraindications are estrogen-dependent neoplasms, thromboembolic disorders, and liver disease.
An abnormal amount of lipid in blood is called dyslipidemia, which includes abnormal levels of cholesterol, triglycerides, and/or lipoproteins. Dyslipidemia may be primary (familial) or secondary (acquired). Both primary and secondary causes can lead to the development of premature cardiovascular (atherosclerosis) disease. Familial causes are classified according to the Fredrickson system, which looks into the pathology and the lipids that are elevated. Certain types do not increase the risk of premature atherosclerotic disease but still impact overall cardiac risk and chance of cardiovascular events in the future. Screening, early diagnosis, and strict control and management are the keys to prevention of cardiovascular events.
The foot is the terminal portion of the lower limb, whose primary function is to bear weight and facilitate locomotion. The foot comprises 26 bones, including the tarsal bones, metatarsal bones, and phalanges. The bones of the foot form longitudinal and transverse arches and are supported by various muscles, ligaments, and tendons that allow for flexibility as well as dynamic and static support. The foot has 3 primary arches and multiple ligaments that are essential to its structure. The arches are important in absorbing weight during standing, walking, and running and the ability to adapt to uneven terrain during locomotion.
Volume status is a balance between water and solutes, the majority of which is Na. Volume depletion (also known as hypovolemia) refers to a loss of both water and Na, whereas dehydration refers only to a loss of water. Dehydration is primarily caused by decreased water intake and presents with increased thirst and can progress to altered mental status and low blood pressure if severe. Volume depletion can be caused by GI losses, renal losses, bleeding, poor oral Na intake, or third spacing of fluids. The clinical presentation has relatively nonspecific symptoms but will ultimately cause low blood pressure if severe. The diagnosis of these imbalances is based on lab findings in addition to clinical symptoms and signs, which can be subtle and unreliable. Management requires differentiation between these 2 conditions. The treatment is to administer fluids with tonicity similar to those lost; isotonic fluids are used for volume depletion, and hypotonic fluids are used for dehydration.
The hepatobiliary system is composed of the liver, gallbladder, and bile ducts (within the liver and external to the liver). The liver produces bile, which is a fluid made of cholesterol, phospholipids, conjugated bilirubin, bile salts, electrolytes, and water. Bile, which assists in digestion and helps eliminate waste products, is stored in the gallbladder. The hepatobiliary system can be affected by infections, cysts, solid masses, ischemia, and mechanical flow obstruction, which mandate the presence of reliable imaging tests to determine the etiology. The methods that evaluate structural changes in the liver and biliary tract include ultrasonography, CT scan, and MRI (including magnetic resonance cholangiopancreatography). Additionally, cholescintigraphy, a functional imaging study, helps identify gallbladder pathology by tracking the biliary pathway.
Noninvasive ventilation (NIV) is an advanced respiratory support that does not require an artificial, invasive airway. This technique is commonly used during acute respiratory failure. The most common forms of NIV are noninvasive positive pressure ventilation (NIPPV) and high-flow nasal cannula (HFNC). In acute respiratory failure, NIV is frequently used to prevent intubation for invasive mechanical ventilation, if there are no contraindications. There are more established contraindications to NIPPV in comparison to HFNC, but NIPPV has demonstrated clear mortality benefit in chronic obstructive pulmonary disease and congestive heart failure exacerbations.
Imaging of the internal female reproductive organs (including the uterus, ovaries, and fallopian tubes) is indicated to diagnose common gynecologic complaints, most commonly in cases of abnormal bleeding, pelvic pain, and to evaluate masses, congenital anomalies, and infertility. Ultrasound is almost always the 1st-line imaging modality of choice, whereas MRI is typically reserved for complicated or indeterminate cases as a follow-up. Computed tomography is almost never used for primary gynecologic assessments. Fallopian tubes are not visible on either ultrasound or MRI if they are normal. The best way to assess tubal patency is by using hysterosalpingography, a fluoroscopic exam in which a dye is injected into the uterine cavity, followed by the study of its flow through the fallopian tubes.
Female breasts, made of glandular, adipose, and connective tissue, are hormone-sensitive organs that undergo changes along with the menstrual cycle and during pregnancy. Breasts may be affected by various diseases, in which different imaging methods are important to arrive at the correct diagnosis and management. Mammography is used for breast cancer screening and diagnostic evaluation of various breast-related symptoms. Ultrasonography is rarely used for screening, but it is typically used for diagnostic workup and during procedures (e.g., breast biopsy). MRI of the breasts is used as a supplementary screening tool for those at high risk for developing breast cancer. Additionally, in individuals with breast implants, inconclusive mammographic and/or breast ultrasound findings, and diagnosed breast cancer needing evaluation pretreatment and posttreatment, MRI is an important breast radiologic tool.
An airway, breathing, and circulation (ABC) assessment is the mainstay for evaluating and treating critically ill individuals. The airway assessment helps identify individuals with potential obstruction of the airway, which may benefit from airway management techniques to ensure adequate ventilation and oxygenation. Measures to relieve and prevent soft-tissue obstruction in an unconscious individual can include special positioning maneuvers and airway adjuncts (such as oropharyngeal or nasopharyngeal airways). By relieving obstruction, assisted breathing with a bag-mask is more effective. Endotracheal intubation provides a more definitive way to ensure airway patency and protection.
Congestive heart failure (CHF) is a progressive syndrome characterized by the failure of the heart to maintain the metabolic demands of the body either due to systolic or diastolic dysfunction. Treatment of CHF is centered around lifestyle modifications (salt and fluid restriction, smoking cessation, and weight loss) and pharmacologic management. Acute worsening of heart failure is often secondary to other medical conditions and is managed with aggressive diuresis and interventions to support cardiac and ventilatory functions. Angina is defined as chest pain or discomfort resulting from myocardial ischemia. Therapy for angina is targeted at limiting platelet aggregation and adhesion (with antiplatelet agents), reducing O2 demand (with beta-blockers), reducing preload (with nitrates), and preventing the progression of atherosclerotic disease (using statin therapy), along with the management of comorbidities.
Non-Hodgkin lymphomas (NHLs) are a diverse group of hematologic malignancies that are clonal proliferative disorders of mature or progenitor B cells, T cells, or natural killer (NK) cells. Most pediatric cases are aggressive and high-grade (but curable); in adults, low-grade subtypes are more common. Like Hodgkin lymphoma, which has distinct pathologic features and treatments, NHL often presents with constitutional signs of fever, night sweats, and weight loss. Clinical features include lymphadenopathy and hepatosplenomegaly, but some individuals present with extranodal involvement and abnormal lab findings. B-cell NHLs include diffuse large B-cell lymphoma, follicular lymphoma, Burkitt lymphoma, mantle cell lymphoma, and marginal zone lymphoma. T-cell NHLs include adult T-cell lymphoma and mycosis fungoides. Diagnosis is made by lymph node biopsy, bone marrow biopsy, or both. Management is with chemotherapy or targeted drugs. Radiation therapy is used in adults but not in children, and stem cell transplantation is used for patients with aggressive disease.
Diagnostic procedures in gynecology are useful in identifying the presence of disease, determining the progression of disease, and monitoring the response of the organs to treatment. The major diagnostic procedures include speculum examinations, sonography (ultrasound), colposcopy, cervical biopsy and endocervical curettage, loop electrosurgical excision procedures, vulvar biopsy, endometrial biopsy, hysteroscopy, and hysterosalpingography (HSG). All of these procedures can be performed in the office setting or in a radiology suite, though in certain situations they are performed in the OR if more sedation or increased monitoring is required.
Purines and pyrimidines are heterocyclic aromatic compounds, which, along with sugar and phosphate groups, form the important components of nucleotides. Purines include adenine and guanine, while pyrimidines include thymine (in DNA), uracil (in RNA), and cytosine. Purine nucleotide synthesis follows a series of reactions using carbon donors, amino acids (e.g., glutamine, aspartate), and bicarbonate. The de novo pathway generates inosine monophosphate (IMP), which is the precursor of adenosine monophosphate (AMP) and guanosine monophosphate (GMP). Purine synthesis is regulated in the 1st 2 steps. Synthesis of pyrimidine nucleotides also follows different reactions, producing uridine monophosphate (UMP), which is converted to uridine triphosphate (UTP) and cytidine triphosphate (CTP). For thymine, a part of deoxyribonucleotides, ribonucleoside reductase is required to reduce the ribose moiety. Degradation of nucleotides result in xanthine then uric acid production in purines, while pyrimidines produce the amino acids, Î²-alanine, and Î²-aminobutyrate.
Lipids are a diverse group of hydrophobic organic molecules, which include fats, oils, sterols, and waxes. Fatty acids are integral building blocks of lipids, and can be classified as unsaturated or saturated based on the presence/absence of carbon-carbon double bonds within their nonpolar chains. Eicosanoids are a family of cell-signaling molecules with important physiologic properties derived from the fatty acid, arachadonic acid. In addition, combining fatty acids with different bases, including glycerol, phosphate, and shingosine, results in different lipids with varied functions within the human body. Glycerolipids (triacylglycerols) are important for energy storage and thermal insulation. Glycerophospholipids and sphingolipids are essential constituents of cellular plasma membranes. Another group of lipids is based off of isoprenoids, which are the building blocks of sterols (such as cholesterol). Altered levels of lipids (both an overabundance or deficiency) can result in many potential disease processes.
Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia due to impaired insulin secretion (type 1 DM), insulin resistance (type 2 DM), or both (latent autoimmune diabetes in adults (LADA)). The goal of diabetes management is to prevent chronic serious and potentially disabling complications due to damage to various organs. Adequate long-term control of blood glucose is crucial in the prevention of complications. Macrovascular complications include heart disease, stroke, peripheral vascular disease, and CKD in various stages, including end-stage renal disease that requires dialysis. Microvascular disease can cause retinopathy, neuropathy, or symptomatic cardiac disease, which are not seen during stress testing or angiogram that are used to diagnose large vessel diseases.
The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The fallopian tubes receive an ovum after ovulation and help move it and/or a fertilized embryo toward the uterus via ciliated cells lining the tubes and peristaltic movements of its smooth muscle. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. The transition point is known as the squamocolumnar junction, which is the site of most cervical cancers. These organs are supplied by the uterine and ovarian arteries and innervated by the autonomic nervous system.
Urologic cancer is a broad term that involves cancer of the male and female urinary tracts and male reproductive organs. Risk factors for urologic cancer are smoking; exposure to chemicals such as benzidine and beta-naphthylamine, and arsenic; genetic predisposition; and chronic irritation of the urinary system. Clinical presentation includes painless hematuria, flank and/or suprapubic pain, dysuria, and unexplained significant weight loss. The gold standard for diagnosis is endoscopy of the urologic structures (cystoscopy, cystourethroscopy, ureteropyeloscopy) with biopsy. Additional studies include radiologic imaging, which gives information about the tumor invasion and spread of the disease to other sites or organs. Management includes surgery, chemotherapy, radiotherapy, and supportive treatment, depending on the location, extent, and histology.
Spinal cord injuries are complex injuries that involve damage to the neural tissue within the spinal canal. Spinal cord injuries are commonly the result of trauma. Clinical presentation varies depending on the site of injury and on whether the injury is complete or incomplete. Diagnosis is by clinical exam and imaging. Management is 2-fold, with immediate supportive care and stabilization of spine followed by long-term rehabilitation with physiotherapy and treatment of complications. Spinal cord injuries are associated with multisystem complications.
The adult human body is made up of 60% water and is divided into extracellular and intracellular fluid compartments. Extracellular fluid is present outside the cells and makes up â…“ of the total body water. Intracellular fluid is present inside the cells and makes up â…” of the total body water. Intracellular and extracellular fluids are separated into compartments by semipermeable membranes, and the transport of fluid and ions is maintained by channels in the cell membrane. Each compartment contains different concentrations of ions and osmolar molecules. The relative charge and osmolarity are maintained rigorously by the transport of water and substances between compartments. Hypernatremia, hyponatremia, and edema are the clinical conditions arising from disturbances in the maintenance of osmolarity of the body fluid compartments.
Body temperature can be divided into external temperature, which involves the skin, and core temperature, which involves the CNS and viscera. While external temperature can be variable, the core temperature is maintained within a narrow range of 36.5â€“37.5ÂºC (97.7â€“99.5ÂºF). Although the reasons are unknown, it has been hypothesized that a narrow temperature range is maintained for the metabolic rate needed for the functioning and optimization of cellular processes. Regulation of the core temperature is one of the most critical functions of the nervous system and is achieved by physiologic and behavioral feedback and feed-forward mechanisms that are mainly regulated by the hypothalamus. Any change in body temperature or environmental temperature triggers responses that lead to the quick and efficient resetting of homeostasis.
Vascular surgery is the specialized field of medicine that focuses on the surgical management of the pathologies of the peripheral circulation. The main goal of most vascular procedures is to restore circulatory function to the affected vessels by relieving occlusions or by redirecting blood flow (e.g., bypass). Surgical intervention is either open or endovascular. Vascular interventions require a multidisciplinary approach, including vascular surgeons, interventional radiologists, anesthesiologists (or anesthetists), nurses, physiotherapists, and occupational therapists.
A tachyarrhythmia is a rapid heart rhythm, regular or irregular, with a rate > 100 beats/min. Tachyarrhythmia may or may not be accompanied by symptoms of hemodynamic change. Pathologic tachyarrhythmias resulting in hemodynamic instability can be caused by intrinsic cardiac abnormalities, systemic diseases, or medication toxicity. Supraventricular arrhythmias are called narrow-complex tachycardias and originate in the sinoatrial (SA) node, atrial myocardium, or atrioventricular (AV) node. Ventricular arrhythmias originate below the AV node and are characterized by a wide QRS complex. Diagnosis is made by physical exam and ECG. Management is directed toward the type of tachyarrhythmia present and its underlying cause.
The abdominal organs are derived primarily from endoderm, which forms the primitive gut tube. The gut tube is divided into 3 regions: foregut, midgut, and hindgut. The foregut gives rise to the lining of the GI tract from the esophagus to the upper duodenum, as well as the liver, gallbladder, and pancreas. The midgut gives rise to the GI tract lining between the midduodenum and midtransverse colon. The hindgut gives rise to the GI tract lining from the midtransverse colon through the upper anal canal. The mesoderm gives rise to the muscles of the GI tract wall, connective tissue (including the mesenteries and omenta), and the vasculature. The ectoderm gives rise to the nerve tissue and the lining of the lower anal canal.
Both gastrulation and neurulation are critical events that occur during the 3rd week of embryonic development. Gastrulation is the process by which the bilaminar disc differentiates into a trilaminar disc, made up of the 3 primary germ layers: the ectoderm, mesoderm, and endoderm. During this process, a structure called the notochord is formed in the midline in the mesodermal layer; the notochord is critical in inducing neurulation. Neurulation is the process by which some of the ectoderm in the trilaminar embryo develops into the neural tube and neural crest cells, which will go on to form all of the neural tissue in the body. This process is completed by the end of the 3rd week.
The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 â€œhipâ€ bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. The pelvic ring joints include the pubic symphysis anteriorly and the sacroiliac joints posteriorly. The hip bones are made up of 3 fused bones: the pubis, ischium, and ilium. The pelvic cavity houses various GI, urinary, and reproductive structures, which are supported by the muscles and connective tissue of the pelvic floor. The female pelvis, making accommodations for childbirth, is generally wider and larger than the male pelvis.
Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Pain symptoms are seen every day, by every physician, in every clinic and hospital in the world. Understanding pain physiology is the cornerstone to understanding how to treat it and to providing the individual with their first sigh of relief as definitive management is undertaken.
The anterior abdominal wall is anatomically delineated as a hexagonal area defined superiorly by the xiphoid process, laterally by the midaxillary lines, and inferiorly by the pubic symphysis. From the superficial to deep order, the anterior abdominal wall consists of the skin, subcutaneous tissue, muscle, transversalis fascia, and peritoneum. The lateral abdominal muscles include the external and internal obliques and the transversus abdominis. Anterior abdominal muscles include the rectus abdominis and pyramidalis muscles. The abdominal wall is primarily supplied by epigastric arteries and innervated by thoracoabdominal nerves.
Liver function tests, also known as hepatic function panels, are one of the most commonly performed screening blood tests. Such tests are also used to detect, evaluate, and monitor acute and chronic liver diseases. Liver function tests assess the levels of various hepatic proteins and enzymes to determine the state of liver metabolic activity, homeostasis, bile metabolism, and protein synthesis capacity. The standard hepatic panel includes the levels of total protein, bilirubin, albumin, ALT, AST, AST/ALT ratio, and alkaline phosphatase (ALP).
The urinary tract is located in the abdomen and pelvis and consists of the kidneys, ureters, urinary bladder, and urethra. The structures permit the excretion of urine from the body. Urine flows from the kidneys through the ureters to the urinary bladder and out through the urethra. The bladder acts as a reservoir for urine until micturition is appropriate. Regulation of micturition relies on the CNS and the spinal cord.
The muscles of the neck can be divided into 3 groups: anterior, lateral, and posterior neck muscles. Each of the groups is subdivided according to function and the precise location of the muscles. The muscles of the neck are mainly responsible for the movements of the head (i.e., extension, flexion, lateral flexion-extension, and rotation), but the deep muscles also contribute to more intricate functions (i.e., speaking and swallowing).
The prostate is a gland in the male reproductive system. The gland surrounds the bladder neck and a portion of the urethra. The prostate is an exocrine gland that produces a weakly acidic secretion, which accounts for roughly 20% of the seminal fluid. The prostate consists of multiple lobes and is made up of glandular and fibromuscular tissue. The glandular tissue has ducts that empty into the prostatic portion of the urethra, and the fibromuscular tissue encircles the urethra.
The inguinal region, or the groin, is located in the RLQ and LLQ of the anterior abdominal wall, bordered by the thigh inferiorly, the pubis medially, and the iliac crest superolaterally. The inguinal canal is a tubular structure that runs in a straight line from the anterior superior iliac spine to the pubic tubercle. The canal contains the spermatic cord in men and the round ligament in women. This region is clinically relevant, as it is the site for the most common type of hernias, such as indirect and direct inguinal hernias. Patients with hernias will present with a unilateral bulge in the groin that may be associated with pain. In symptomatic or high-risk cases, hernias can be repaired surgically.
Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall laterally by the suspensory ligament of the ovary and to the uterus medially by the utero-ovarian ligament. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes), which are expelled and then â€œcapturedâ€ by the uterine tubes. The primary blood supply to the ovary is provided by the ovarian artery, a direct branch of the abdominal aorta; the ovarian artery anastomoses with the ascending branch of the uterine artery, providing excellent collateral blood flow.
The heart is a 4-chambered muscular pump made primarily of cardiac muscle tissue. The heart is divided into 4 chambers: 2 upper chambers for receiving blood from the great vessels, known as the right and left atria, and 2 stronger lower chambers, known as the right and left ventricles, which pump blood throughout the body. Blood flows through the heart in 1 direction, moving from the right side of the heart, through the lungs, and then returning to the left side of the heart, where it is pumped out to the rest of the body. As blood moves through the heart, 4 important valves prevent backflow. The heart muscle itself is supplied by the coronary arteries. The heart also has its own conduction system, triggering its own rhythmic contractions.
Juvenile idiopathic arthritis (JIA), formerly known as juvenile rheumatoid arthritis, is a heterogeneous group of inflammatory diseases characterized by inflammation of 1 or more joints and is the most common pediatric rheumatic disease. Juvenile idiopathic arthritis is classified according to its clinical presentation, and diagnosis is made with examination findings as well as confirmatory lab testing showing evidence of inflammation and characteristic X-ray findings. Treatment is directed at preventing loss of function and controlling or limiting joint damage, with a variable prognosis depending on the type.
Antiemetics are medications used to treat and/or prevent nausea and vomiting. These drugs act on different target receptors. The main classes include benzodiazepines, corticosteroids, atypical antipsychotics, cannabinoids, and antagonists of the following receptors: serotonin, dopamine, and muscarinic and neurokinin receptors. Anticholinergics and antihistamines are useful in the treatment of vestibular causes of nausea. Serotonin and neurokinin antagonists are effective in the management of chemotherapy-induced nausea and vomiting. Antiemetics should be used with caution, though, because of their adverse effects. Serotonin antagonists and some dopamine antagonists cause QT-interval prolongation. Dopamine antagonists are associated with extrapyramidal symptoms. Additionally, many agents cause sedation and have anticholinergic effects, which can aggravate underlying diseases.
Premenstrual dysphoric disorder (PMDD) refers to a group of mood, somatic, and behavioral symptoms that follow a cyclical pattern experienced by some women prior to menstruation. Unlike premenstrual syndrome (PMS), PMDD is characterized by significant distress and/or functional impairment. Diagnosis is made clinically with history and physical exam. Management is 2-fold: via lifestyle modification and pharmacotherapy with serotonin reuptake inhibitors or oral contraceptives.
Nephritic syndrome is a broad category of glomerular diseases characterized by glomerular hematuria, variable loss of renal function, and hypertension. These features are in contrast to those of nephrotic syndrome, which includes glomerular diseases characterized by severe proteinuria, although there is sometimes overlap of > 1 glomerular disease in the same individual. The clinical presentations of nephritic syndrome are highly varied, from asymptomatic with urinary abnormalities to life-threatening critical illness. Diagnosis is suggested by hematuria, mild-to-moderate proteinuria, and certain serologies (e.g., ANCA); kidney biopsy is necessary in most cases. Management varies as widely as the clinical presentations, from watchful waiting in mild cases to immunosuppression and plasmapheresis in aggressive disease.
Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. The primary etiologies of nephrotic syndrome are minimal change disease, membranous nephropathy, and focal segmental glomerulosclerosis. The clinical presentation of nephrotic syndrome includes proteinuria (> 3.5 g/day), hypoalbuminemia (< 3 g/dL), and peripheral edema. Other frequently observed clinical findings are hyperlipidemia and thrombotic disease. Diagnosis is suggested by the clinical findings, and kidney biopsy is necessary in most cases. Management varies with the etiology and usually involves glucocorticoids or other immunosuppressant drugs.
Renal tubular acidosis (RTA) is an imbalance in physiologic pH caused by the kidneyâ€™s inability to acidify urine to maintain blood pH at physiologic levels. Renal tubular acidos3s exist in multiple types, including distal RTA (type 1), proximal RTA (type 2), and hyperkalemic RTA (type 4). Depending on the type of RTA, various mechanisms cause dysfunction of renal acidâ€“base handling, resulting in a nonâ€“anion-gap metabolic acidosis. All RTAs present clinically with some degree of metabolic acidosis; however, distal RTA and proximal RTA also have hypokalemia, while hyperkalemic RTA does not. Diagnosis is primarily through the history and laboratory analysis, including measurement of serum and urine anion gaps. Treatment involves the correction of chronic metabolic acidosis with alkali to prevent its long-term catabolic effects on bone and muscles, as well as addressing any underlying causes leading to the RTA.
Polyneuropathy is any disease process affecting the function of or causing damage to multiple nerves of the peripheral nervous system. There are numerous etiologies of polyneuropathy, most of which are systemic and the most common of which is diabetic neuropathy. The clinical presentation varies by etiology as well as classification of the polyneuropathy, but generally manifests as sensorimotor disturbances (pain, paresthesia, numbness, weakness, and loss of coordination and balance), which have a gradual onset and progressive course. Distal nerves are affected most commonly, but the disease process may progress proximally with time or progression of the underlying etiologic disease entity. Diagnosis is made clinically, but laboratory studies, electrodiagnostic testing, and/or nerve biopsy may be required in some cases. Management varies depending on the etiology.
Complex regional pain syndrome (CRPS) is a chronic regional neuropathic pain condition characterized by excruciating pain (out of proportion to apparent tissue damage or inciting trauma), paresthesia, allodynia, temperature abnormalities, skin discoloration, edema, reduced range of motion, and bone demineralization. This syndrome is most often associated with an inciting traumatic event (e.g., fracture, surgery, burn) and predominantly affects the limb(s). Diagnosis is clinical, but it is supported by imaging and electrodiagnostic testing. Treatment centers around multidisciplinary pain management and maintenance of function.
Distal radius fractures are one of the most common fractures encountered in practice and are often associated with falling onto an outstretched hand. These fractures are most frequently seen in older individuals, especially women. In this population, these fractures are related to an increase in falls due to gait instability with aging and associated osteoporosis. In younger individuals, distal radius fractures are usually related to high-energy trauma. Individuals often present with pain and a dinner fork deformity of the distal forearm. Diagnosis is clinical and confirmed with x-rays of the wrist. Treatment can be operative or nonoperative depending on the age of the individual, articular involvement, and degree of displacement or angulation.
Antiestrogens are medications decreasing the estrogenic effects in the body. The antiestrogens include selective estrogen receptor modulators (SERMs), selective estrogen receptor downregulators (SERDs), aromatase inhibitors, and several others, which include medications suppressing the gonadotropins or counteracting the effects of estrogen. Antiestrogens are most commonly used in the treatment of breast cancer but also treat precocious puberty, gynecomastia, anovulatory infertility, and several gynecologic complaints. Adverse effects include hot flashes, venous thromboembolic events, bone mineral density loss, and ischemic cardiovascular events. Antiestrogens are contraindicated in individuals with known hypersensitivity reactions and pregnancy.
Fetal growth restriction (FGR), also known as intrauterine fetal growth restriction (IUGR), is an estimated fetal weight (EFW) or abdominal circumference < 10th percentile for gestational age. The term small for gestational age (SGA) is sometimes erroneously used interchangeably with FGR. However, SGA refers to babies born with a birth weight < 10th percentile for gestational age. Defining FGR is challenging because each fetus has a different growth potential that may not be accounted for. The most commonly recognized classifications for FGR are symmetrical or asymmetrical. Symmetrical FGR occurs when all parts of the fetus are equally small and is typically the result of a complication early in pregnancy. Asymmetrical FGR occurs when there is disproportionately lagging growth in different body parts; most commonly, the fetus will have a normal size head and a small body. The causes of FGR can be broadly grouped into maternal, fetal, and placental. Fetal growth restriction is diagnosed by ultrasonography and confirmed by weight at birth. Management is often targeted to the underlying etiology, if known. Depending on the etiology, these fetuses may be at increased risk for complications such as preterm birth, intrauterine fetal death, and neurologic sequelae. Close surveillance and delivery planning by a skilled provider is crucial.
Breastfeeding is often the primary source of nutrition for the newborn. During pregnancy, hormonal stimulation causes the number and size of mammary glands in the breast to significantly increase. After delivery, prolactin stimulates milk production, while oxytocin stimulates milk expulsion through the lactiferous ducts, where it is sucked out through the nipple by the infant. Breastfeeding has many benefits for the mother and baby, including a decreased risk of infections, GI distress, and atopic disease for the infant; and a decreased risk of anemia, cardiovascular disease, and breast and ovarian cancer for the mother. True contraindications to breastfeeding exist but are quite rare. Important clinical conditions associated with breastfeeding include engorgement, mastitis, galactocele, breast abscess, and infant jaundice.
Neurosurgery is a specialized field focused on the surgical management of pathologies of the brain, spine, spinal cord, and peripheral nerves. General neurosurgery includes cases of trauma and emergencies. There are a number of specialized neurosurgical practices, including oncologic neurosurgery, spinal neurosurgery, and pediatric neurosurgery. Common neurosurgery cases treat tumors, masses, herniations, various types of hemorrhages, and radicular pain. Although neurosurgery is a surgical specialty, neurosurgeons must be very competent in neurology, critical care, trauma care, and radiology.
Instances of traumatic force applied to the chest are seen in 10% of the cases of pediatric trauma, usually in the context of motor vehicle accidents and falls. Chest trauma rarely occurs in isolation and is often associated with polytrauma. The 2 major mechanisms involve blunt and penetrating forces. Pneumothorax, hemothorax, flail chest, and lung contusions are the most common injuries. Treatment of affected children is very similar to that of adults, but unique pediatric pathoanatomy dictates important differences in approach and management.
Androgens are naturally occurring steroid hormones responsible for development and maintenance of the male sex characteristics, including penile, scrotal, and clitoral growth, development of sexual hair, deepening of the voice, and musculoskeletal growth. Androgens are primarily given to treat hypogonadism, gender dysphoria in transgender men, and low testosterone in older men (controversial). Antiandrogenic drugs decrease the effect of androgens. Classes include androgen receptor blockers, 5Î±-reductase inhibitors, and androgen synthesis inhibitors. Both men and women may use antiandrogens, which treat advanced prostate cancer, benign prostatic hyperplasia (BPH), alopecia, and hirsutism.
Anesthesiology is the field of medicine that focuses on interventions that bring a state of anesthesia upon an individual. General anesthesia is characterized by a reversible loss of consciousness along with analgesia, amnesia, and muscle relaxation. General anesthesia is induced via the administration of gaseous or injectable agents before surgical procedures or other medical interventions. On the other end of the spectrum is local anesthesia, which is achieved via the use of topical agents or the local administration of injectable anesthetics to the area of concern. The use of anesthetics has been well documented in history, but the practice of modern anesthesiology only began by the end of the 18th century.
Pharmacological treatment of pulmonary hypertension (PH) (characterized by an elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure) includes various classes of drugs. These medications fall into the following drug categories: phosphodiesterase type-5 (PDE-5) inhibitors, soluble guanylate cyclase (sGC) stimulants, prostacyclin receptor agonists, endothelin receptor antagonists, and calcium channel blockers (CCBs). Via differing pathways, the overall effect of the medications is vascular smooth muscle relaxation and vasodilation resulting in a fall in pulmonary arterial pressure. Contraindications, adverse events, and drug interactions are dependent on the class of drugs.
Neuropathy is a nerve pathology presenting with sensory, motor, or autonomic impairment secondary to dysfunction of the affected nerve. The peripheral nerves (outside the brain and spinal cord), are derived from several plexuses, with the brachial and lumbosacral plexuses supplying the major innervation to the extremities. Mononeuropathy (affecting a single nerve) and plexopathy (affecting the plexus) can occur from trauma, compression, and systemic diseases. The clinical presentation varies according to location, type of nerves affected, and cause of the damage. Diagnosis requires a thorough physical examination, and diagnostic tests include laboratory tests, imaging and a confirmatory nerve conduction study, and electromyography. Management depends on the etiology but centers around physical therapy, supportive care, and treatment of underlying issues.
Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus is the most virulent species; S. epidermidis and S. saprophyticus are less virulent but are also clinically significant. Infection can cause a wide array of disease, including cellulitis, abscesses, endocarditis, osteomyelitis, and medical device infections. Toxins formed by S. aureus can cause gastroenteritis, SSSS, and toxic shock syndrome (TSS). Antibiotic management varies based on the type of infection, severity, and sensitivity data.
Transplantation is a procedure that involves the removal of an organ or living tissue and placing it into a different part of the body or into a different person. Organ transplantations have become the therapeutic option of choice for many individuals with end-stage organ failure. Transplantation can offer the individual a definitive treatment for a given disease entity. Over the past 50 years, organ transplantation has become established worldwide, with ever-improving results, conferring an immense benefit to hundreds of thousands of individuals. Both solid organs and bone marrowâ€“derived hematopoietic cells can be successfully transplanted for a number of different indications. Tolerance of the transplanted organ by the immune system of the host is achieved through the use of immunosuppressive and immunomodulating strategies. The main complications of transplantation are organ rejection or graft failure; however, chronic immunosuppression also carries the risk of serious complications, including potentially life-threatening infections.
The urogenital system is derived from intermediate mesoderm. The intermediate mesoderm differentiates into nephrogenic cords (which will go on to form the urinary system) and an adjacent area known as the gonadal ridge (which will go on to form the gonads). The nephrogenic cords elongate in a caudal direction and sequentially develop 3 different structures: the pronephros (rudimentary and nonfunctional), the mesonephros (forms the primitive urinary system), and the metanephros (forms the permanent kidney). Concurrently, the genital system develops in close association with the urinary system. Genital development depends on chromosomal sex, which determines whether the primitive gonads differentiate into testes or ovaries. The gonads then secrete certain hormones, which direct further development of both the internal and external genital structures.
The ANS is a component of the peripheral nervous system that uses both afferent (sensory) and efferent (effector) neurons, which control the functioning of the internal organs and involuntary processes via connections with the CNS. The ANS consists of the sympathetic and parasympathetic nervous systems. The efferent nerve fibers that terminate in the endocrine, vascular, and visceral structures coordinate the inner workings of the body in response to several afferent inputs. The sympathetic and parasympathetic neural circuits coordinate stress responses and relaxation responses, respectively. The enteric nervous system regulates visceral organ function. A balance between these systems results in homeostasis, whereas an imbalance leads to pathological conditions.
Immunosuppressants are a class of drugs widely used in the management of autoimmune conditions and organ transplant rejection. The general effect is dampening of the immune response. There are multiple targets in the immune system, as well as varied mechanisms in inhibiting inappropriate immune activity. Biologic agents are medications derived from living organisms that target particular components of the immune system. The targets can be tumor necrosis factor (TNF), interleukins (ILs), or B- or T-cell activity. Calcineurin inhibitors halt the activity of calcineurin, a phosphatase involved in T-cell activation. Corticosteroids interfere with the cell cycle of inflammatory cells and modify the activity of other immune components. mTOR inhibitors are proliferation signal inhibitors, reducing immune-cell proliferation. Some immunosuppressants, such as cytotoxic agents, have antineoplastic activity; these are used in rheumatoid arthritis, as prophylaxis for transplant rejection, and for malignant diseases.
Candida is a genus of dimorphic, opportunistic fungi. Candida albicans is part of the normal human flora and is the most common cause of candidiasis. Risk factors for infection include conditions or agents that may lead to an immunocompromised state, disruption of the normal flora, and/or disturbance of the mucosal barrier. The clinical presentation varies and can include localized mucocutaneous infections (e.g., oropharyngeal, esophageal, intertriginous, and vulvovaginal candidiasis) and invasive disease (e.g., candidemia, intraabdominal abscess, pericarditis, and meningitis). The diagnosis is made by identifying Candida on KOH preparation, cultures, or tissue biopsy. Treatment depends on the extent and site of infection, and includes topical or systemic antifungal medications
There are 2 types of sex chromosomes in humans: X and Y. Chromosomal sex is male when a Y chromosome is present (e.g., 46,XY or 47,XXY) and female when the Y chromosome is absent (e.g., 46,XX or 45,X0). Male phenotypes develop when a specific gene, called the SRY gene (usually found on the Y chromosome), is present, stimulating differentiation of the gonads into testes. The testes then produce testosterone (triggering development of the penis and scrotum externally and the ejaculatory system internally) and antimüllerian hormone (AMH), which causes regression of the müllerian ducts. Without the SRY gene, ovaries develop; without testosterone, external female genitalia develop; and without AMH, the müllerian ducts persist and differentiate into the fallopian tubes, uterus, and upper vagina.
The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. The skin is composed of surface epithelium, exocrine components, connective tissue, muscles, and nerves. The primary role of the skin is to serve as a protective barrier between the internal body and the external environment; it also protects the body from excessive fluid loss.
Before the developing blastocyst reaches the uterine wall, it needs to undergo several stages of differentiation. After a continuous process of cleavage and compaction, the morula gives rise to the trophoblast and embryoblast, which are the primary components of the blastocyst. Uterine fluid passes through the zona pellucida to form the blastocyst cavity. When the blastocyst reaches the endometrium, implantation begins by the trophoblast dividing into the cytotrophoblast and syncytiotrophoblast, with the syncytiotrophoblast primarily being responsible for invading the endometrium. The embryoblast divides into the epiblast and hypoblast, which are responsible for creating the amniotic cavity and yolk sac, respectively.
The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. The kidneys also play a major role in homeostatic processes, including electrolyte concentration, blood pressure, and acid–base regulation. Grossly, they consist of an outer cortex and inner medulla. Microscopic functional units known as nephrons filter the blood through a structure called the glomerulus, and this filtrate is then modified and concentrated as it moves through a complex tubular system. The renal arteries supply the kidneys via a central opening, known as the renal hilum, on its medial side; large renal veins empty directly into the vena cava.
Labor is defined as regular, effective uterine contractions resulting in cervical changes that culminate in expulsion of the fetus and products of conception. Complications may arise during childbirth that necessitate prompt recognition and management by the delivering team. Four important complications/topics related to the moments surrounding delivery include episiotomy and lacerations, operative vaginal deliveries (forceps and vacuum-assisted deliveries), shoulder dystocia, and amniotic fluid embolism.
Gout medications include antiinflammatory and urate-lowering medications. Colchicine is an antiinflammatory medication that can be used for acute gout flares. The urate-lowering drug classes include the xanthine oxidase inhibitors, uricosuric agents, and uricases. These medications are beneficial for the prevention of gout exacerbations and work through a variety of mechanisms. Xanthine oxidase inhibitors are the most commonly used urate-lowering therapy; these work by inhibiting the enzyme necessary for the conversion of purines to uric acid. Uricosuric agents reduce reabsorption of uric acid by the proximal tubule, thereby increasing renal excretion. Lastly, the urases are recombinant enzymes that metabolize uric acid to allantoin. In addition to gout, urate-lowering treatment can also be used for other indications, such as the prevention of tumor lysis syndrome and uric acid nephrolithiasis.
Brown-Séquard syndrome (BSS) is a rare neurologic injury that causes hemisection of the spinal cord, resulting in weakness and paralysis of one side of the body and sensory loss on the opposite side. This syndrome is most often due to trauma, but it may also occur with disc herniation, hematoma, or tumor. Clinical presentation is consistent with ipsilateral damage to the corticospinal tracts and posterior columns (weakness, loss of proprioception, and vibration sensation) below the level of the lesion, and contralateral anterior column symptoms owing to the unilateral involvement of the spinothalamic tract (loss of pain and temperature sensation). Diagnosis is confirmed with MRI. Management depends on the etiology and site of injury, and timely intervention is associated with a favorable prognosis and recovery.
Membranoproliferative glomerulonephritis (MPGN) is also known as mesangiocapillary glomerulonephritis. Membranoproliferative glomerulonephritis is a pattern of glomerular injury characterized by mesangial hypercellularity, endocapillary proliferation, and thickening of the glomerular basement membrane (double contour formation). The changes are due to the deposition of Igs, complement factors, or both, in the glomerular mesangium and along the glomerular capillary walls. The pathogenic variants include immune complex/monoclonal Ig-mediated (e.g., from infections, autoimmune diseases) and complement-mediated MPGN. In rare cases, MPGN is not associated with Igs and the complement system, such as in the case of endothelial injury. With multiple etiologies, the presentation and clinical course vary. Presenting features can be asymptomatic proteinuria and hematuria, nephrotic syndrome, nephritic syndrome, or chronic renal failure. Definitive diagnosis requires renal biopsy, although additional laboratory and imaging tests may point to the associated disease. Treatment is based on the underlying cause. Steroids, immunosuppressants, and kidney transplantation are among the commonly used treatment modalities.
Intravenous anesthetics have been used in modern anesthesia practice since the 20th century. Modern anesthesia began with inhaled anesthetics; however, intravenous agents were adopted because injected or infused doses could be more closely controlled with little wasted medication. Several groups of agents are currently available (e.g., barbiturates, benzodiazepines, and dissociatives), but the most widely used are fentanyl, midazolam, and propofol.
Antidepressants encompass several classes of medications and are used to treat individuals with depression, anxiety, and other psychiatric conditions, as well as to manage chronic pain and menopausal symptoms. Bupropion is an atypical antidepressant that acts by increasing neurotransmitter levels and alleviates the symptoms of depression. Brexanolone is a neurosteroid mainly used for the management of postpartum depression.
The testicles, also known as the testes or the male gonads, are a pair of egg-shaped glands suspended within the scrotum. The testicles have multiple layers: an outer tunica vaginalis, an intermediate tunica albuginea, and an innermost tunica vasculosa. The testicles are composed of testicular lobules (contain interstitial tissue) and seminiferous tubules (produce spermatozoa). Blood supply to the testicles is primarily provided by the testicular artery. Venous drainage is through testicular veins.
The breasts are found on the anterior thoracic wall and consist of mammary glands surrounded by connective tissue. The mammary glands are modified apocrine sweat glands that produce milk, which serves as nutrition for infants. Breasts are rudimentary and usually nonfunctioning in men. The shape and size of the breasts change during a womanâ€™s life and menstrual cycles. Breasts are supplied by the axillary, internal thoracic, and intercostal arteries, and they are innervated by branches of the cervical plexus.
Non-insulinotropic diabetes medications are used to treat type 2 diabetes by methods other than increasing insulin secretion. This group of medications includes the biguanides, thiazolidinediones, alpha-glucosidase inhibitors, sodium–glucose transport protein 2 inhibitors, and amylin analogs. Mechanisms of action vary, but they can include increasing peripheral insulin sensitivity, reducing glucagon release, inhibiting gluconeogenesis, slowing glucose absorption, and increasing satiety. Metformin is the initial medication of choice; others may be used as an alternative monotherapy or as adjunctive therapy. Most of these medications are not associated with severe hypoglycemia, except for amylin analogs or when medications are used in conjunction with other hypoglycemic agents.
There are multiple different types of malignancies that can affect the vulva. The most common histologic type is squamous cell carcinoma (SCC), which accounts for approximately 75%–85% of all vulvar cancers. Other types include melanoma, basal cell carcinoma, sarcoma, malignancy of the Bartholin glands, and Paget disease of the vulva (an adenocarcinoma). Squamous cell carcinoma is typically associated with either high-risk HPV infection or lichen sclerosus. Vulvar cancer presents as vulvar lesions that can have a variety of appearances, which may include warty or nodular masses, scaly plaques, pigmented lesions, and ulcers; pruritus is also common. Diagnosis usually requires a biopsy, and management is primarily with surgical excision. Unfortunately, lymph node metastasis occurs early in the natural history of the disease and is associated with a poor prognosis.
Insulinotropic diabetes medications treat type 2 diabetes mellitus by increasing insulin secretion, which results in decreased glucose levels. The group of medications includes sulfonylureas, meglitinides, glucagon-like peptide-1 (GLP-1) receptor agonists, and DPP-4 inhibitors. The agents are usually used in combination with other therapies for diabetes management. Sulfonylureas and meglitinides are associated with weight gain, while GLP-1 agonists may provide the added benefit of weight loss. Other side effects vary between the drug classes. None of the medications should be used in the treatment of type 1 diabetes mellitus or diabetic ketoacidosis.
Labor is the normal physiologic process defined as uterine contractions resulting in dilatation and effacement of the cervix, which culminates in expulsion of the fetus and the products of conception. Labor has 3 stages: the 1st stage starts with the onset of regular contractions, the 2nd stage starts with full cervical dilation, and the 3rd stage starts immediately after fetal delivery and ends with delivery of the placenta. The primary factors required for labor to progress normally are the three Ps: power (uterine contractions), passenger (the fetus), and passage (the maternal pelvis). Labor may become abnormally protracted and require augmentation, usually with oxytocin, to prevent maternal and fetal complications.
Primary vaginal cancers are malignant tumors that originate from cells in the vagina. Squamous cell carcinoma (SCC) is by far the most common (80%–85%); other histologic types include adenocarcinomas, sarcomas (including sarcoma botryoides, typically seen in children), and melanomas. Vaginal SCC is most commonly associated with HPV infections, while clear cell adenocarcinomas are associated with in utero exposure to diethylstilbestrol (DES). Individuals typically present with vaginal bleeding and/or an irregular mass or lesion on exam; other symptoms may include abnormal discharge, pain, and urinary or defecatory symptoms. A biopsy is required for diagnosis. Staging is based on tumor size, extent of local invasion, and metastasis. Management may be surgical for stage I disease, but surgery is typically avoided in advanced disease, which is instead managed with radiation and chemotherapy.
Endometrial hyperplasia (EH) is the abnormal growth of the uterine endometrium. This abnormal growth may be due to estrogen stimulation or genetic mutations leading to uncontrolled proliferation. Endometrial carcinoma (EC) is the most common gynecologic malignancy in the developed world, and it has several histologic types. Endometrioid carcinoma (known as type 1 EC) typically develops from atypical endometrial hyperplasia, is hormonally responsive, and carries a favorable prognosis. Other histologic types are known as type 2 EC; they tend to present at more advanced stages, are not hormonally responsive, and carry a far worse prognosis. Women with both EH and EC tend to present with postmenopausal or irregular menstrual bleeding. Diagnosis is histologic. Management most often involves progestin therapy, surgery, and adjuvant radiation therapy (for advanced disease).
Spontaneous abortion, also known as miscarriage, is the loss of a pregnancy before 20 weeks' gestation. However, the layperson use of the term “abortion” is often intended to refer to induced termination of a pregnancy, whereas “miscarriage” is preferred for spontaneous loss. Most spontaneous abortions occur within the 1st 12 weeks of gestation and can be caused by several factors such as infection, trauma, and genetic and autoimmune causes. There are different types of spontaneous abortions, including threatened, inevitable, incomplete, complete, and missed abortions. Spontaneous abortions are diagnosed based on history, physical examination, and ultrasound findings. Management options include expectant, medical, or surgical therapy.
Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. There are several forms of insulin, and they differ in their time of onset, peak effect, and duration. Insulin can be classified as fast acting, short acting, intermediate acting, or long acting. A combination of classes can be used to maintain glucose control throughout the day. Common adverse effects include hypoglycemia, weight gain after initiation of an insulin regimen, and local injection site changes.
Multiple pregnancy, or multifetal gestation, is a pregnancy with more than 1 fetus. Multiple pregnancy with more than 2 fetuses is referred to as a higher-order multiple pregnancy and the most common type of multiple pregnancy is a twin pregnancy. Due to advanced maternal age and evolving assisted reproductive technology, the rates of multiple pregnancies have steadily increased over the past 3 decades. However, rates have slowly plateaued with the increase of the single embryo transfer. The perinatal mortality and morbidity rates of twin pregnancies are 3–7x higher than singleton pregnancies primarily because of higher rates of preterm delivery. Multiple pregnancies also carry a higher risk of obstetric complications such as congenital anomalies, preeclampsia, and gestational diabetes. Multiple pregnancies are classified as high-risk and require astute obstetric care.
Ovarian cancer is a malignant tumor arising from the ovarian tissue and is classified according to the type of tissue from which it originates. The 3 major types of ovarian cancer are epithelial ovarian carcinomas (EOCs), ovarian germ cell tumors (OGCTs), and sex cord-stromal tumors (SCSTs). By far, EOCs are the most common, tend to present in postmenopausal women with advanced disease, and carry a poor prognosis. On the other hand, OGCTs and SCSTs frequently affect younger women, tend to present earlier, and carry a better prognosis. Affected individuals are frequently asymptomatic, although they may present with nonspecific symptoms such as fatigue, increasing abdominal girth, GI symptoms, and pelvic pain. Moreover, if the tumor secretes hormones, abnormal bleeding may be a presenting symptom. Diagnosis is suspected based on imaging studies and confirmed with histologic examination. Treatment is primarily surgical and often with adjuvant chemotherapy.
There are several benign vulvar diseases, but some of the most common are Bartholin cyst and abscess, lichen sclerosus, and lichen simplex chronicus. Bartholin cysts are formed due to an obstruction in the excretory duct that causes retention of their secretions (lubricating mucus). Bartholin cysts present as nontender fluctuant masses at the 4 and/or 8 o'clock positions in the labia. If a Bartholin cyst becomes infected, it can develop into an extremely painful abscess. Lichen sclerosus is a chronic dermatologic condition that causes progressive thinning and fibrosis of the vulvar, perineal, and perianal skin, and presents classically with itching and white plaques. Lichen simplex chronicus is a thickening of the vulvar skin due to chronic itching or rubbing, which often occurs in the setting of atopic or contact dermatitis.
Hormonal contraceptives (HCs) contain synthetic analogs of the reproductive hormones estrogen and progesterone, which may be used either in combination or in progestin-only formulations for contraception. These formulations act synergistically to produce antiovulatory effects and can also affect the endometrial lining (typically decreasing bleeding and pain associated with menstruation), which is why they are also used to treat a variety of gynecologic issues. Available formulations include oral contraceptive pills (combined and progestin-only), transdermal patches, vaginal rings, progestin injections, subdermal implants, and intrauterine devices. Common adverse effects include nausea, headaches, mood changes, and irregular bleeding. Importantly, estrogens increase the risk of venous thromboembolism (VTE) and are contraindicated in individuals at risk for VTE. Other important contraindications include pregnancy, liver disease, and breast cancer.
Multitrauma occurs when 2 or more traumatic injuries occur in at least 2 areas of the body. A systematic management approach is necessary for individuals who have undergone trauma to maximize outcomes and reduce the risk of undiscovered injuries. Assessment of multitrauma starts with a primary survey followed by the A-B-C-D-E scheme, involving securing of the airway (A), and evaluating breathing (B), circulation (C), recognition of neurologic deficits or disability (D), and exposure to environmental control (E). Once the primary survey is completed, a secondary survey is performed to obtain pertinent history and nature of the trauma based on a thorough examination and diagnostic studies. The A-B-C-D-E approach is crucial for the overall stabilization, treatment, and identification of any missed injuries.
Carpal tunnel syndrome (CTS) is a complex of signs and symptoms caused by compression of the median nerve as it crosses the carpal tunnel. Presentation is with pain and paresthesia of the dermatomal target tissues innervated by the median nerve as well as weakness and atrophy of the nerve's myotomal targets. Risk factors that cause a predisposition to CTS include obesity, female sex, pregnancy, diabetes, inflammatory conditions, genetic predisposition, and occupational factors. A clinical diagnosis may be made on the basis of history and physical examination and confirmed with electrodiagnostic testing. Conservative management includes splinting and physical therapy; more severe cases may require surgical correction.
The brachial plexus is a network of nerves that originate from the lower cervical and upper thoracic nerve roots. The causes of brachial plexopathies include traumatic injuries, birth-related injuries, iatrogenic procedures, neoplastic processes, and previous treatment with radiation. Patients present with sensory and motor deficits related to the site of the lesion and the nerves involved. Diagnosis is made based on clinical findings, imaging, and electrodiagnostic studies. Treatment is related to the underlying cause and may be medical or surgical.
Posterior cord syndrome (PCS) is an incomplete spinal cord syndrome affecting the dorsal columns, the corticospinal tracts (CSTs), and descending autonomic tracts to the bladder. Posterior cord syndrome is rare but has a diverse range of etiologies, including demyelinating disorders, degenerative spinal conditions, neoplastic causes, vascular abnormalities, and hereditary neurodegenerative disorders. Clinical symptoms include gait ataxia, paresthesias with loss of position and vibration sense, and urinary incontinence. The diagnosis is made clinically and with neuroimaging. Management addresses treatment of the underlying cause.
Neurofibromatosis type 2 is a neurocutaneous disorder that can arise from mutations in the NF2 gene located in chromosome 22 and may be inherited in an autosomal dominant fashion or occur from de novo mutations. The main clinical features are bilateral vestibular schwannomas, intracranial/spinal meningioma, and intramedullary and extramedullary spinal tumors. Other features can include eye lesions such as cataracts, skin lesions, and peripheral neuropathy. Diagnosis is made clinically from history and examination and confirmed with MRI, molecular testing, and histopathology. Tumor surveillance and follow-up with screening of at-risk family members is recommended. Management includes surgical interventions, radiation therapy, and/or monoclonal antibody therapy with bevacizumab.
Neurofibromatosis type 1 (NF1), also known as phakomatosis, is a neurocutaneous disorder that is most commonly of autosomal dominant inheritance due to mutations in the NF1 gene. Neurofibromatosis type 1 presents a range of clinical manifestations with the most prominent features being various pigmented skin lesions called café au lait macules (CALMs), benign nerve-sheath tumors called neurofibromas, freckling of the inguinal and axillary regions, and iris hamartomas, referred to as Lisch nodules. At least half of the individuals with NF1 have learning disabilities. Neurofibromatosis type 1 may also cause osteodysplasia and malignant transformation of tumors. The diagnosis is based on the typical clinical presentation and can be confirmed with genetic testing. Management depends on the clinical presentation and may vary from surgical removal to chemotherapy/radiotherapy for tumors, occupational therapy and PT for motor impairments, treatment with growth hormone, and bracing in the case of bone abnormalities.
Inhaled anesthetics are chemical compounds, which can induce and maintain general anesthesia when delivered by inhalation. Inhaled anesthetics can be divided into 2 groups: volatile anesthetics and gases. Volatile anesthetics include halothane, isoflurane, desflurane, and sevoflurane. Nitrous oxide (N2O) is the most common of the anesthetic gases; cyclopropane and xenon are less commonly used. While the exact mechanism of action of the inhaled anesthetics is unknown, the drugs are believed to have variable effects on GABA, glycine, glutamate, and NMDA receptors in the CNS. Inhaled anesthetics have been used for medical purposes for the last 200 years.
Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri, is a clinical disorder that presents with symptoms due to increased intracranial pressure (ICP; ≥ 20 mm Hg) or CSF pressure (> 250 mm H2O), with no structural changes or other attributable causes. The condition is most commonly observed in obese women and after intake of certain drugs, such as growth hormones, tetracycline antibiotics, and high dosages of vitamin A. Classic manifestations include headache, vision loss or visual-field defects, and papilledema. Diagnosis is made by clinical exam, imaging, and lumbar puncture. Management is aimed at decreasing ICP and includes medication, therapeutic CSF removal, and shunting.
Syncope is a short-term loss of consciousness and loss of postural stability followed by spontaneous return of consciousness to the previous neurologic baseline without the need for resuscitation. The condition is caused by transient interruption of cerebral blood flow that may be benign or related to a underlying life-threatening condition. Syncope is not a distinct disease entity; rather, it is a symptom of another pathologic process, whether it be transient or a more established disease process. Syncope may be accompanied by other symptoms, such as light-headedness, sweating, palpitations, nausea, feeling warm or cold, and visual blurring. Workup includes a detailed history and physical examination, electrocardiography, echocardiography, provocative testing (tilt-table test), or imaging of the suspected culprit vasculature. In many cases, a definite etiology is not found. Management is based on the underlying cause and can include physical countermaneuvers, stopping offending drugs, volume resuscitation, blood transfusion, and/or cardiac or vascular interventions.
Antiviral agents against human herpesviruses (HHVs) include acyclovir, cidofovir, and foscarnet. Human herpesviruses are DNA viruses in the Herpesviridae family. Herpes simplex virus (HSV), varicella-zoster virus (VZV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), and HHV-8 belong to the Herpesviridae family. Antivirals against the group generally act via inhibition of DNA polymerase. Acyclovir (the prototypical nucleoside analog) requires viral kinase for phosphorylation to become a triphosphate, which is incorporated in viral DNA. Cidofovir requires phosphorylation by host cellular kinase, which allows cidofovir to have activity against mutated viruses and become deficient in viral kinase. Foscarnet (a pyrophosphate analog) does not require phosphorylation. Nephrotoxicity is a shared adverse effect in the agents. Acyclovir can also cause obstructive crystalline nephropathy and foscarnet carries a risk of electrolyte abnormalities and seizures. The nephrotoxic effect of cidofovir can be reduced with IV saline and probenecid.
Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased ICP can lead to brain herniation and death if not treated promptly. Clinical presentation includes headache, drowsiness or altered level of consciousness, and papilledema. Diagnosis is suspected based on the clinical presentation and confirmed with urgent brain imaging. Immediate management includes measures to decrease ICP, medications including diuretics, and surgery.
Antivirals for hepatitis B include the nucleoside/nucleotide analogs, also known as nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs). Because of their similar chemical structure to nucleosides and nucleotides, NRTIs are able to integrate into viral DNA during the replication process. This process inhibits the function of viral RNA-dependent DNA polymerase, resulting in chain termination. All of these medications are administered orally and are excreted by the kidneys. Indications include chronic hepatitis B infection, and some (such as lamivudine) are also used for HIV. Adverse effects include GI symptoms, evidence of mitochondrial toxicity (such as lactic acidosis), and rebound infection upon discontinuation.
Intracerebral hemorrhage (ICH) refers to a spontaneous or traumatic bleed into the brain parenchyma and is the 2nd-most common cause of cerebrovascular accidents (CVAs), commonly known as stroke, after ischemic CVAs. Trauma, hypertension, vasculopathy, vascular malformations, tumors, coagulopathy, and hemorrhagic conversion of ischemic stroke may all be causative factors. Clinical presentation may vary depending on the size and location of the hemorrhage and may range from headache, neurologic signs and symptoms, and altered level of consciousness to coma. Treatment includes stabilization, stopping or reversing of anticoagulation, blood pressure control, monitoring in a neurologic ICU, and possible neurosurgical intervention. Intracerebral hemorrhage is associated with significant morbidity and mortality.
Bone, while seemingly inert, is an active, growing, and changing part of the human body, in addition to being the body's primary calcium reservoir. In the correct homeostatic conditions, bone can remodel in response to damage, stress, or hormonal signaling (parathyroid hormone and calcitonin). Osteocytes located deep in the bone sense damage and signal bone-lining cells that will begin the process of remodeling. This process is vital not only for damage repair but also to adapt to a new environment and conditions.
Intravenous fluids (IVFs) are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Crystalloids and colloids have different general compositions, which affect distributions through the body’s fluid compartments and guide clinical use. Crystalloid solutions are typically used for patients who are hypovolemic, dehydrated, or have ongoing fluid losses. Colloidal solutions may be used in cases of low oncotic pressure. Providers should choose fluid types based on the clinical scenario and best available evidence. All recipients of IVFs should be closely monitored to determine the goal and status of the fluid therapy.
Epidural hemorrhage (EDH) is an event characterized by bleeding into the epidural space between the dural layers of the meninges and the skull. The primary mechanism triggering bleeding is trauma (i.e., closed head injury), which causes arterial injury, most commonly middle meningeal artery injury. Epidural hemorrhage presents acutely, usually immediately (seconds to hours) following head trauma, with an altered level of consciousness that may span from a momentary loss of consciousness to coma. Diagnosis is based on clinical suspicion following head trauma and is confirmed with neuroimaging (i.e., noncontrast head CT). Management includes stabilization, stopping (possibly, the reversal) of all anticoagulants, monitoring in a neurologic ICU, and neurosurgical intervention.
To undergo fertilization, the sperm enters the uterus, travels towards the ampulla of the fallopian tube, and encounters the oocyte. The zona pellucida (the outer layer of the oocyte) deteriorates along with the zygote, which travels towards the uterus and eventually forms a blastocyst, allowing for implantation to occur. An ectopic pregnancy occurs if the zygote does not reach the uterus before the zona pellucida degrades.
Subdural hemorrhage (SDH) is bleeding into the space between the dural and arachnoid meningeal layers surrounding the brain. The most common mechanism triggering the bleeding event is trauma (e.g., closed head injury) causing a tearing injury to the extracerebral “bridging” veins, but rupture of small arteries within this space or intracranial hypotension may also be causative. Acute SDH presents, immediately following head trauma, with an altered level of consciousness that may span from a momentary loss of consciousness to coma, which makes it a potentially life-threatening condition. Chronic SDH may also occur, presenting with a more gradual neurologic deterioration. Diagnosis is based on clinical suspicion following head trauma and confirmed with neuroimaging (e.g., noncontrast head CT). Management includes stabilization, stopping (possibly reversing) all anticoagulants, monitoring in a neurologic ICU, and neurosurgical intervention.
Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. The basic pathophysiology of all etiologies of hyponatremia is an abnormal increase in total body water (TBW), which dilutes the total body sodium (TBNa+) concentration. The clinical presentation varies greatly, from asymptomatic to subtle cognitive deficits, seizures, and death. Management is guided by etiology, acuity, and duration of symptoms, usually involving oral fluid restriction or administration of IV fluids that contain Na. Sodium must be replaced slowly, as overly rapid correction of hyponatremia can lead to irreversible neurologic complications and death, known as the osmotic demyelination syndrome (ODS).
Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Rapidly progressive glomerulonephritis is associated with nephrotic syndrome and is a manifestation of different diseases. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. The major mechanisms of immunologic injury are classified into anti-glomerular basement membrane (anti-GBM) disease, pauci-immune crescentic glomerulonephritis, and immune complex-mediated injury. Rapidly progressive glomerulonephritis can manifest with hematuria, proteinuria, and varying degrees of edema and hypertension. Diagnosis is by presentation, laboratory tests, imaging, and renal biopsy. Prompt treatment is essential because RPGN can develop into end-stage renal disease within a short period of time. Modalities include corticosteroids, cyclophosphamide or other immunosuppressants, and plasmapheresis (depending on the underlying disease).
Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. The most classic symptom is a sudden-onset (thunderclap) headache along with neck stiffness, vomiting, a decreased level of consciousness, and seizure. As with any stroke, focal neurologic deficits are commonly present, and rapid neurologic deterioration may ensue without prompt diagnosis and intervention. An SAH should be suspected in any person presenting with thunderclap headache and neurologic symptoms, and the diagnosis can be confirmed with neuroimaging or lumbar puncture (LP). Treatment consists of reversal of anticoagulation, control of blood pressure, and neurosurgical intervention to contain the bleed and/or relieve elevated intracranial pressure (ICP). Even with prompt neurosurgical intervention, SAH carries a high mortality rate.
Gametogenesis is the development of gametes from primordial germ cells. This process differs between the sexes. In males, spermatogenesis produces spermatozoa. In females, oogenesis results in an ovum. The process starts with the migration of primordial germ cells from the yolk sac to the gonadal ridge. Oogenesis starts during the embryonic and fetal periods, whereas spermatogenesis starts at puberty. However, the phases of gametogenesis are similar, with germ cells progressing through mitosis, meiosis I, meiosis II, and maturation. This process results in gametes that are haploid, with 23 chromosomes.
Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. The major cellular response involves neutrophils and macrophages to phagocytose and lyse the injurious organism or repair necrosed tissue after injury. Inflammation can be pathologic if it is prolonged or when normal processes create an excessive response (such as with atherosclerosis). There are multiple mediators of inflammation that overlap with innate immunity when they respond to injurious stimuli. Inflammation can become chronic, resulting in the formation of granulomas, tissue damage, and the loss of organ function.
Portal hypertension is increased pressure in the portal venous system. This increased pressure can lead to splanchnic vasodilation, collateral blood flow through portosystemic anastomoses, and increased hydrostatic pressure. There are a number of etiologies, including cirrhosis, right-sided congestive heart failure, schistosomiasis, portal vein thrombosis, hepatitis, and Budd-Chiari syndrome. Most individuals are asymptomatic until complications arise, including esophageal varices, portal hypertensive gastropathy, ascites, and hypersplenism. The diagnosis is clinical, but it can be supported by ultrasound findings (and hepatic venous pressure gradient measurement in unclear cases). Management requires treating the underlying etiology and managing the complications. This can include nonselective beta blockers to prevent bleeding from varices, diuretics and sodium restriction for ascites, and transjugular intrahepatic portosystemic shunt for refractory complications.
Hepatitis C is an infection of the liver caused by the hepatitis C virus (HCV). Hepatitis C virus is an RNA virus and a member of the genus Hepacivirus and the family Flaviviridae. The infection can be transmitted through infectious blood or body fluids and may be transmitted during childbirth or through IV drug use or sexual intercourse. Hepatitis C virus can cause both acute and chronic hepatitis, ranging from a mild to a serious, lifelong illness including liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis C infection is diagnosed by testing for the presence of HCV antibodies and HCV RNA. Management is supportive but includes direct antiviral agents (DAAs) if infection does not resolve spontaneously.
Hepatitis B virus (HBV) is a partially double-stranded DNA virus, which belongs to the Orthohepadnavirus genus and the Hepadnaviridae family. Hepatitis B virus is transmitted by exposure to infectious blood or body fluids. Examples of types of exposure include sexual intercourse, IV drug use, and childbirth. The virus can cause potentially life-threatening liver disease. Most individuals with acute HBV infection are asymptomatic or have mild, self-limiting symptoms. Chronic infection can be asymptomatic or create hepatic inflammation, leading to liver cirrhosis and hepatocellular carcinoma (HCC). Management of acute hepatitis is typically supportive. Administration of antivirals or liver transplantation may be necessary in fulminant and chronic cases.
The rectum and anal canal are the most terminal parts of the lower GI tract/large intestine that form a functional unit and control defecation. Fecal incontinence can occur if this function is disturbed. Fecal continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters. Peristaltic waves within the rectal muscularis, involuntary relaxation of the internal anal sphincter (controlled by the ANS), and voluntary relaxation of the external anal sphincter (controlled by the cerebral cortex) are essential for defecation to occur. The rich plexus of veins surrounding the anal canal can develop into hemorrhoids if dilated.
The pharynx is a component of the digestive system that lies posterior to the nasal cavity, oral cavity, and larynx. The pharynx can be divided into the oropharynx, nasopharynx, and laryngopharynx. Pharyngeal muscles play an integral role in vital processes such as breathing, swallowing, and speaking. The muscles of the pharynx receive innervation from the vagus and glossopharyngeal nerve to propel food from the oral cavity into the esophagus.
The nose is the human body's primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. There are 12 cranial bones that contribute to the structure of the nose's walls and nasal conchae.
Genital herpes infections are common sexually transmitted infections caused by herpes simplex virus (HSV) type 1 or 2. Herpes simplex virus type 1 is more commonly associated with non-genital herpes, while HSV-2 is more commonly associated with genital herpes. Primary infection often presents with systemic, prodromal symptoms followed by clusters of painful, fluid-filled vesicles on an erythematous base, dysuria, and painful lymphadenopathy. Primary infection can also be asymptomatic. Herpes infections are unique in that the virus is able to remain dormant in the neuronal ganglia, which allows for recurrent infections. Recurrent outbreaks are usually less severe than the initial infection. Treatment is with antiviral therapy, primarily acyclovir.
Pseudomembranous colitis is a bacterial disease of the colon caused by Clostridium difficile. Pseudomembranous colitis is characterized by mucosal inflammation and is acquired due to antimicrobial use and the consequent disruption of the normal colonic microbiota. C. difficile infections account for the most commonly diagnosed hospital-acquired diarrheal illnesses. C. difficile infections can range from asymptomatic colonization to diarrhea and progress to fulminant colitis with systemic sepsis in severe cases. The diagnosis is established based on stool studies. Management of pseudomembranous colitis is mainly using antibiotics. Fecal transplant is considered in a few cases, whereas surgical intervention is required in severe cases.
Perforated viscus or GI perforation represents a condition in which the integrity of the GI wall is lost with subsequent leakage of enteric contents into the peritoneal cavity, resulting in peritonitis. The causes of perforated viscus include trauma, bowel ischemia, infections, or ulcerative conditions, all of which ultimately lead to a full-thickness disruption of the intestinal wall. Perforated viscus presents as sudden onset of abdominal pain, distention, nausea, vomiting, obstipation, and symptoms of peritonitis. Diagnosis relies on the medical history as well as imaging studies, including abdominal and pelvic CT scan and X-ray. Treatment includes bowel rest, the use of a nasogastric tube, antibiotics to avoid severe infections or sepsis, analgesics, and surgical repair.
Sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. The condition usually occurs concurrently with inflammation of the nasal mucosa (rhinitis), a condition known as rhinosinusitis. Acute sinusitis is due to an upper respiratory infection caused by a viral, bacterial, or fungal agent. Viral etiologies are the most common cause. Sinusitis presents with facial pain over the affected sinus and purulent rhinorrhea. Diagnosis is usually clinical and management is supportive, although it may require antibiotics.
Gestational trophoblastic diseases are a spectrum of placental disorders resulting from abnormal placental trophoblastic growth. These disorders range from benign molar pregnancies (complete and partial moles) to neoplastic conditions such as invasive moles and choriocarcinoma. Diagnosis is confirmed by elevated serum beta human chorionic gonadotropin (hCG) and ultrasound findings, which are dependent on the disorder. Treatment is primarily through dilation and curettage and/or methotrexate.
Congestive heart failure refers to the inability of the heart to supply the body with normal cardiac output to meet metabolic needs. Echocardiography can confirm the diagnosis and give information about the ejection fraction. Treatment is directed at the removal of excess fluid and decreasing oxygen demand of the heart. Prognosis depends on the underlying cause, compliance with medical therapy, and presence of comorbidities.
Ventricular fibrillation (VF or V-fib) is a type of ventricular tachyarrhythmia (> 300/min) often preceded by ventricular tachycardia. In this arrhythmia, the ventricle beats rapidly and sporadically. The ventricular contraction is uncoordinated, leading to a decrease in cardiac output and immediate hemodynamic collapse. Ventricular fibrillation is most commonly caused by underlying ischemic heart disease. It leads to death within minutes unless advanced cardiac life support measures are started immediately.
Granulomatosis with polyangiitis (GPA) is a rare autoimmune disease of unknown etiology. It leads to a necrotizing granulomatous inflammation of small and medium-sized blood vessels of the nose, sinuses, throat, lungs, and kidneys. Early stages of GPA often present with localized manifestations such as infections of the upper respiratory tract, skin lesions, and/or constitutional symptoms. Later stages can present with renal failure and severe respiratory disease. Early diagnosis and treatment of granulomatosis with polyangiitis (which involves the administration of corticosteroids and immunosuppressive agents such as methotrexate) may lead to a full remission but without treatment, the condition has a high mortality rate.
Long QT syndrome (LQTS) is a disorder of ventricular myocardial repolarization that produces QT prolongation on electrocardiogram (ECG). Long QT syndrome is associated with an increased risk of developing life-threatening cardiac arrhythmias, specifically torsades de pointes. The condition may be congenital or acquired. Congenital LQTS is attributed to genetic mutations affecting cardiac ion channels. Acquired LQTS usually results from drug therapy and/or electrolyte abnormalities. Patients can be asymptomatic or present with palpitations, syncope, seizures, and even sudden cardiac death. Diagnosis is established with ECG along with medical and family history, laboratory workup, and other cardiac tests. Treatment is determined by etiology. Acquired LQTS requires removal of the offending drug and correction of electrolyte abnormalities. Congenital LQTS management involves avoidance of triggers of arrhythmia, intake of beta-blockers, and placement of an implantable cardioverter-defibrillator (ICD).
Cri du chat is the French term for "cat-cry" or "call of the cat." The term refers to the cat-like cry of a pediatric patient with cri-du-chat syndrome. The condition is a rare genetic disorder caused by deletion mutations on chromosome 5. Cri-du-chat syndrome is more common in females than in males. Aside from the characteristic cry, the condition also presents with dysphagia, low birth weight, poor growth, and severe cognitive, speech, and motor disabilities.
Crohn's disease is a chronic, recurrent condition that causes patchy transmural inflammation that can involve any part of the gastrointestinal tract. It is a type of inflammatory bowel disease (IBD) along with ulcerative colitis (UC). The terminal ileum and proximal colon are usually affected. Crohn's disease typically presents with intermittent, non-bloody diarrhea and crampy abdominal pain. Extraintestinal manifestations may include calcium oxalate renal stones, gallstones, erythema nodosum, and arthritis. Diagnosis is established via endoscopy with biopsy that shows transmural inflammation, characteristic “cobblestone” mucosa, and noncaseating granulomas. Management is with corticosteroids, azathioprine, antibiotics, and anti-TNF agents (infliximab and adalimumab). Complications include malabsorption, malnutrition, intestinal obstruction or fistula, and an increased risk of colon cancer.
5-alpha-reductase deficiency is an autosomal recessive intersex or “disorder of sex development” (DSD) condition caused by a loss-of-function mutation in a gene on chromosome 2. The affected subjects have a 46,XY karyotype, bilateral testes, and normal testosterone production but have impaired virilization during embryogenesis due to defective conversion of testosterone to dihydrotestosterone (DHT), which is a significantly more potent androgen. This leads to male pseudohermaphroditism or ambiguous genitalia in males. Also known as pseudovaginal perineoscrotal hypospadias, these patients present with a clitoris-like phallus, cryptorchidism, bifid scrotum, and a rudimentary prostate. No Müllerian structures are present.
Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Pain is a subjective experience. Acute pain lasts < 3 months and typically has a specific, identifiable cause. Chronic pain lasts > 3 months and may exist in the absence of tissue damage or after healing would have been expected to occur. Pain management involves a combination of addressing underlying causes and using a systematic approach tailored to the clinical scenario.
Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Diagnosis is clinical. Management requires treating the underlying disease, managing complications, and, if required, liver transplantation.
Precocious puberty (PP) is the appearance of secondary sexual characteristics due to elevated sex hormones before the age of 6–8 in girls and 9 in boys. Excess hormone secretion may occur only at the level of the sex hormone or may involve the whole hypothalamic-pituitary-gonadal axis. Measurement of sex hormone levels, as well as X-rays to evaluate skeletal maturity, are used to diagnose and characterize PP. Correcting the hormonal excess at its root cause can appropriately delay the onset of puberty. A primary goal of treatment is the preservation of normal height potential.
Benign breast epithelial lesions are grouped histologically as nonproliferative, proliferative without atypia, and atypical hyperplasia. The classifications are based on subsequent cancer risk in either breast. The nonproliferative type carries no risk, while fibroadenoma, the most common benign tumor, is a proliferative breast lesion (i.e., has a slight increase in malignancy risk). Because atypical hyperplasia shares some features with breast carcinoma in situ, future cancer potential is increased. Management ranges from frequent monitoring to surgical excision, depending on certain factors, including the inherent risk of the pathologic diagnosis. Other breast disorders without malignant possibility are associated with underlying infection or systemic disease, so treatment differs. Benign breast diseases are common but present diversely. It is important to distinguish between them to determine the likelihood of cancer and the best course of treatment.
Congenital diaphragmatic hernias are embryologically derived defects in the diaphragm through which abdominal structures can pass into the chest cavity. The presence of intestines and intra-abdominal organs in the chest interferes with embryonic development of the lungs, which is the major cause of pathology postnatally. Prenatal diagnosis is commonly made by ultrasound during pregnancy followed by confirmation on chest X-ray after birth. Immediate respiratory resuscitation at birth with endotracheal intubation and mechanical ventilation are required. Surgical repair is the only curative option. Prognosis varies, but children with diaphragmatic hernias usually suffer from lifelong pulmonary complications.
Anal fistulas are abnormal communications between the anorectal lumen and another body structure, often to the skin. Anal fistulas often occur due to extension of anal abscesses but are also associated with specific diseases such as Crohn's disease. Symptoms include pain or irritation around the anus; abnormal discharge or purulent drainage; and swelling, redness, or fever if an abscess is present. Management is primarily surgical, with fistulotomy, but can include antibiotics if infection is present. Treatment is surgical. Complications after surgery include recurrence and incontinence.
The menstrual cycle is the cyclic pattern of hormonal and tissular activity that prepares a suitable uterine environment for the fertilization and implantation of an ovum. The menstrual cycle involves both an endometrial and ovarian cycle that are dependent on one another for proper functioning. There are 2 phases of the ovarian cycle (follicular and luteal) and 3 phases of the endometrial cycle (desquamation or menses, proliferative, and secretory). The menstrual cycle is regulated by the hypothalamic-pituitary-ovarian axis via follicle-stimulating hormone (FSH) and luteinizing hormone (LH). A woman’s 1st menstrual cycle is referred to as menarche, and cycles continue until menopause.
Atrioventricular septal defects (AVSDs) are a category of congenital defects of the endocardial cushion and atrioventricular valves (AVVs) resulting in abnormal interatrial and/or interventricular communication. Severe forms present early during infancy with failure to thrive and recurrent pneumonia, and require early surgical correction to avoid pulmonary hypertension.
Ascites is the pathologic accumulation of fluid within the peritoneal cavity that occurs due to an osmotic and/or hydrostatic pressure imbalance secondary to portal hypertension (cirrhosis, heart failure) or non-portal hypertension (hypoalbuminemia, malignancy, infection). Patients often present with progressive abdominal distention and weight gain. Abdominal exam may reveal shifting dullness and a positive fluid wave. Diagnosis is established with an ultrasound, and etiologies can be distinguished by ascitic fluid analysis from paracentesis. Treatment involves dietary sodium restriction, diuretics, and treatment of the underlying cause.
Chronic pancreatitis is due to persistent inflammation, fibrosis, and irreversible cell damage to the pancreas, resulting in a loss of endocrine and exocrine gland function. The most common etiologies are alcohol abuse and pancreatic duct obstruction. Patients often present with recurrent epigastric abdominal pain, nausea, and features of malabsorption syndrome (diarrhea, steatorrhea, and weight loss). Characteristic computed tomography (CT) findings include pancreatic atrophy, dilated pancreatic ducts, and pancreatic calcifications. Therapy focuses on alcohol cessation, diet changes, pain management, and treatment of pancreatic insufficiency.
Tricuspid regurgitation (TR) is a valvular defect that allows backflow of blood from the right ventricle to the right atrium during systole. Tricuspid regurgitation can develop through a number of cardiac conditions that cause dilation of the right ventricle and tricuspid annulus. A blowing holosystolic murmur is best heard at the left lower sternal border. Mild TR may be asymptomatic or present with systemic venous congestion due to increased right atrial and venous pressures. Echocardiography can establish the diagnosis. Treatment focuses on heart failure management, and surgery is reserved for severe disease.
Listeria spp. are motile, flagellated, gram-positive, facultative intracellular bacilli. The major pathogenic species is Listeria monocytogenes. Listeria are part of the normal gastrointestinal flora of domestic mammals and poultry and are transmitted to humans through the ingestion of contaminated food, especially unpasteurized dairy products. Listeria can also infect the fetus in utero or neonates during vaginal birth. Healthy individuals exposed to L. monocytogenes usually do not become ill if the inoculum is small, or may develop only self-limiting gastroenteritis. Immunocompromised or elderly individuals, neonates, and pregnant women can develop invasive disease, including meningitis and bacteremia. Treatment of invasive listeriosis includes ampicillin and gentamicin.
Tricuspid stenosis (TS) is a valvular defect that obstructs blood flow from the right atrium to the right ventricle during diastole. This condition most commonly results from rheumatic heart disease or a congenital defect, and is usually found in conjunction with other valvular disease. A mid-diastolic murmur is best heard at the lower left sternal border. Mild TS may be asymptomatic or present with systemic venous congestion due to increased right atrial and venous pressures. Echocardiography can establish the diagnosis. Treatment focuses on heart failure management, and surgery is reserved for severe disease.
Nonalcoholic fatty liver disease is a spectrum of liver pathology that arises due to accumulation of triglycerides in hepatocytes. Risk factors include diabetes mellitus, insulin resistance, obesity, and hypertension, among others. Nonalcoholic fatty liver disease ranges from fatty liver or hepatic steatosis but can lead to nonalcoholic steatohepatitis (NASH), which features fatty deposits and inflammation. Progressive liver injury and fibrosis irreversibly develop into cirrhosis and, possibly, primary liver cancer. Patients are usually asymptomatic but may present with hepatomegaly and right upper quadrant discomfort. Although liver biopsy is the diagnostic gold standard, the diagnosis can also be established by clinical history, imaging, and laboratory tests. The mainstay of management is lifestyle modifications (weight loss and exercise) with control of associated comorbidities.
Renal artery stenosis (RAS) is the narrowing of one or both renal arteries, usually caused by atherosclerotic disease or by fibromuscular dysplasia. If the stenosis is severe enough, the stenosis causes decreased renal blood flow, which activates the renin-angiotensin-aldosterone system (RAAS) and leads to renovascular hypertension (RVH), which only accounts for a small fraction of all cases of hypertension. Renovascular hypertension can be associated with abdominal bruits, renal insufficiency, or progressive renal atrophy. Diagnosis is by clinical presentation followed by imaging studies, including duplex ultrasonography, magnetic resonance angiography (MRA), computed tomography angiography (CTA), and sometimes catheter-based angiography. Revascularization is usually reserved for cases in which medical therapy has failed.
Valvular disorders can arise from the pulmonary valve, located between the right ventricle (RV) and the pulmonary artery (PA). Valvular disorders are diagnosed by echocardiography. Pulmonary stenosis (PS) is valvular narrowing causing RV outflow tract obstruction. Patients are often asymptomatic unless they have other congenital cardiac anomalies or severe PS. Symptoms (exertional dyspnea, chest pain, and syncope) are due to RV failure. Severe PS is treated surgically.
Neisseria is a genus of bacteria commonly present on mucosal surfaces. Several species exist, but only 2 are pathogenic to humans: N. gonorrhoeae and N. meningitidis. Neisseria species are non-motile, gram-negative diplococci most commonly isolated on modified Thayer-Martin (MTM) agar. These pathogens have many virulence factors, including fimbriae, lipooligosaccharide envelope proteins, a polysaccharide capsule (unique to N. meningitidis), and IgA protease. Gonococcal infections are sexually or perinatally transmitted and include gonorrhea, pelvic inflammatory disease, septic arthritis, and neonatal conjunctivitis. Meningococcal infections are transmitted via respiratory and oral secretions. They most commonly cause meningococcemia with petechial hemorrhages and meningitis.
Budd-Chiari syndrome is a condition resulting from the interruption of the normal outflow of blood from the liver. The primary type arises from a venous process (affecting the hepatic veins or inferior vena cava) such as thrombosis, but can also be from a lesion compressing or invading the veins (secondary type). The patient typically presents with hepatomegaly, ascites, and abdominal discomfort. Onset is often subacute or chronic. Diagnosis is confirmed by Doppler ultrasound. Treatment involves addressing the underlying condition that caused the venous occlusion. Further management involves prevention of further clotting (anticoagulation), restoration of blood flow, and decompressing the liver. Liver transplantation is considered if initial treatment fails and/or the patient has decompensated liver cirrhosis.
Primary biliary cholangitis (PBC) is a chronic disease resulting in autoimmune destruction of the intrahepatic bile ducts. The typical presentation is that of a middle-aged woman with pruritus, fatigue, and right upper quadrant abdominal pain. Elevated liver enzymes and antimitochondrial antibodies (AMAs) establish the diagnosis. Medical management is limited to using ursodeoxycholic acid, a disease-modifying agent. Definitive treatment is liver transplantation, which is performed in late stages (cirrhosis).
A femoral hernia is an uncommon type of groin hernia in which intra-abdominal contents herniate under the inguinal ligament and through the femoral ring into the femoral canal. More common in adults than in children, femoral hernias usually present with swelling that protrudes into the femoral triangle (inferiorly to the inguinal ligament and medial to the femoral vein). Although uncommon, femoral hernias are frequently associated with complications, secondary to the small size of the canal, leading to hernia incarceration and/or strangulation.
Acute cholangitis is a life-threatening condition characterized by fever, jaundice, and abdominal pain which develops as a result of stasis and infection of the biliary tract. Septic shock, liver abscess, and multi-organ dysfunction are potential serious complications. The diagnosis is confirmed with ultrasound showing dilation of the common bile duct (CBD) or gallstones, elevated liver function tests, and leukocytosis. Treatment includes hemodynamic stabilization, broad-spectrum antibiotics, urgent biliary drainage, and cholecystectomy to prevent recurrence.
Atrioventricular (AV) block is a bradyarrhythmia caused by delay, or interruption, in the electrical conduction between the atria and the ventricles. Atrioventricular block occurs due to either anatomic or functional impairment, and is classified into 3 types. The 1st-degree block is due to delayed conduction through the AV node. The 2nd-degree block is characterized by progressive conduction delay or intermittently blocked conduction. The 3rd-degree block involves total interruption in conduction between the atria and ventricles, causing complete AV dissociation. Patients may be asymptomatic or may present with syncope, chest pain, dyspnea, and bradycardia depending on the severity of the block. Electrocardiography (ECG) establishes the diagnosis, and treatment is based on the type of block and hemodynamic stability of the patient.
Acute pancreatitis is an inflammatory disease of the pancreas due to autodigestion. Common etiologies include gallstones and excessive alcohol use. Patients typically present with epigastric pain radiating to the back. Diagnosis requires 2 of 3 criteria, including: characteristic abdominal pain, serum amylase and lipase 3 times the upper limit of normal, or characteristic radiology findings. Ranson’s criteria is commonly used to assess the severity. Management includes aggressive intravenous (IV) hydration, analgesia, nutritional support, and treatment of the underlying cause.
Congenital renal abnormalities arise from embryologic/genetic defects and cause a variety of isolated or syndromic renal disorders, including renal agenesis, dysgenesis, and ectopia. Congenital renal abnormalities are generally identified prenatally and represent approximately ⅓ of all prenatal anomalies. Because of the fetal kidney’s role in the production of amniotic fluid, oligohydramnios detected on prenatal ultrasounds often prompts the workup that identifies congenital renal anomalies. Unilateral renal involvement in the presence of a functioning contralateral kidney may only be an incidental finding later in life. In many cases, treatment is supportive.
Gastroenteritis is inflammation of the stomach and intestines, commonly caused by infections from bacteria, viruses, or parasites. Transmission may be foodborne, fecal-oral, or through animal contact. Common clinical features include abdominal pain, diarrhea, vomiting, fever, and dehydration. Diagnostic testing with stool analysis or culture is not always required, but can help determine the etiology in certain circumstances. The majority of cases of gastroenteritis are self-limited; therefore, the only required treatment is supportive therapy (fluids). However, antibiotics are indicated in severe cases.
The most common benign liver tumors include hepatic hemangiomas, focal nodular hyperplasia, and hepatic adenomas. These tumors are mostly asymptomatic and/or found incidentally on abdominal imaging. While these tumors are benign, large lesions can cause symptoms such as upper abdominal pain, or produce complications such as bleeding. Malignant potential is a concern for hepatic adenoma, depending on risk factors. The diagnosis is based on imaging studies, with characteristic findings defining the tumor. Biopsy generally is reserved for equivocal cases. Management is observation for most small, asymptomatic, and non-growing tumors. However, high-risk factors, symptoms, increasing tumor size, and complications dictate the need for surgical intervention.
Lynch syndrome, also called hereditary non-polyposis colorectal cancer (HNPCC), is the most common inherited colon cancer syndrome, and carries a significantly increased risk for endometrial cancer and other malignancies. Lynch syndrome has an autosomal dominant inheritance pattern involving pathogenic variants in one of the mismatch repair (MMR) genes or epithelial cell adhesion molecule (EpCAM). Diagnosis is made by genetic testing of the index patient and their family members. Management consists of an earlier screening of individuals with defective MMR genes, as well as total colectomy if colorectal neoplasia is discovered. Prophylactic hysterectomy plus salpingo-oophorectomy are recommended for women beyond reproductive age.
Small bowel obstruction (SBO) is an interruption of the flow of the intraluminal contents through the small intestine, and is classified as mechanical (due to physical blockage) or functional (due to disruption of normal motility). The most common cause of SBO in the Western countries is post-surgical adhesions. Small bowel obstruction typically presents with nausea, vomiting, abdominal pain, distention, constipation, and/or obstipation. The diagnosis is established via imaging. Up to 80% of all cases will resolve with supportive management (bowel rest, intravenous (IV) hydration, and nasogastric decompression). However, surgery is required for persistent or complicated cases.
Klinefelter syndrome is a chromosomal aneuploidy characterized by the presence of 1 or more extra X chromosomes in a male karyotype, most commonly leading to karyotype 47,XXY. Klinefelter syndrome is associated with decreased levels of testosterone and is the most common cause of congenital hypogonadism. Symptoms are often not noticed until adolescence or adulthood. Individuals with this condition tend to present as tall, phenotypic men with small testes, decreased body hair, gynecomastia, and infertility. Treatment consists of life-long testosterone replacement therapy.
Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming “stuck.” Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Common causes of functional dysphagia include achalasia, scleroderma, and diffuse esophageal spasm (DES). Mechanical causes of dysphagia include esophageal rings, webs, strictures, and cancer. Oropharyngeal dysphagia may be due to structural abnormalities or abnormal neuromuscular function and coordination. The diagnostic workup depends on the patient’s presenting symptoms, but may include manometry, barium esophagram, or direct visualization with nasopharyngeal laryngoscopy or endoscopy. Treatment varies depending on the underlying cause.
Large bowel obstruction is an interruption in the normal flow of intestinal contents through the colon and rectum. This obstruction may be mechanical (due to the actual physical occlusion of the lumen) or functional (due to a loss of normal peristalsis, also known as pseudo-obstruction). Malignancy and volvulus are the most common causes of mechanical large bowel obstruction. Typical symptoms include intermittent lower abdominal pain, abdominal distention, and obstipation. Diagnosis is established with imaging. Mechanical large bowel obstruction requires surgery in most cases.
A Meckel’s diverticulum is a persistent remnant of the omphalomesenteric (vitelline) duct. A Meckel’s diverticulum is usually located in the antimesenteric border of the ileum. The mucosal lining of the diverticulum may contain heterotopic mucosa (most commonly gastric). Though frequently asymptomatic, a Meckel’s diverticulum can cause ulceration and present with lower gastrointestinal (GI) bleeding. Other complications include diverticulitis or small bowel obstruction (SBO). A Meckel’s scan can detect the diverticulum in hemodynamically stable patients. For those with active bleeding, arteriography is the diagnostic option. The treatment for a symptomatic Meckel’s diverticulum is surgery.
Colorectal cancer (CRC) is the 2nd-leading cause of cancer-related death in the United States. Almost all cases of CRC are adenocarcinoma and the majority of lesions come from the malignant transformation of an adenomatous polyp. As most CRCs are asymptomatic, screening is essential in detecting early disease. Screening is recommended to start at the age of 45 years, utilizing various screening tools available with colonoscopy, flexible sigmoidoscopy, and fecal tests among them. For high-risk individuals, earlier and more frequent screening is recommended. Other stool-based strategies and visualization tests are also available for CRC screening.
Cardiac myxoma is the most common of the primary tumors of the adult heart, all of which are very rare. Cardiac myxoma is a benign neoplasm that arises from primitive multipotent mesenchymal cells. Most occur sporadically, but some are a part of some familial syndromes. All 4 chambers may give rise to myxoma, but 90% originate and grow in the atria, with a left-to-right ratio of approximately 4:1. Diagnosis is made by echocardiography, cardiac magnetic resonance imaging (MRI), or cardiac computed tomography (CT). Complete surgical excision is required because of the substantial risk of embolization and cardiovascular complications, including sudden death.
The human immunodeficiency virus (HIV) is a species of Lentivirus, a genus of the family Retroviridae, which causes HIV infections and acquired immunodeficiency syndrome (AIDS). The virus has high genetic variability and is divided into 2 major types, HIV type 1 (HIV-1) and HIV type 2 (HIV-2). The human immunodeficiency virus is a single-stranded, positive-sense, enveloped RNA virus, which targets and destroys WBCs, leading to frequent opportunistic infections and, eventually, death.
Cervical cancer is the 3rd most common gynecologic cancer. More than 90% of cervical cancer cases are associated with high-risk human papillomavirus (hrHPV), which is transmitted by sexual contact. Cervical cancer can be prevented by early detection and treatment of precancerous lesions caused by hrHPV. The methods of detection are cervical cytology and HPV testing. Screening is recommended by the age of 21 and is generally repeated every 3 years up to the age of 29 in an average-risk individual. By age 30, HPV testing with cytology is obtained. Since the screening program was initiated, there has been a 75% decline in the incidence of and mortality from cervical cancer.
Penetrating chest injuries (PCIs) are caused by an object puncturing the chest wall. Penetrating chest injuries can be high velocity, such as with gunshot wounds (GSWs); medium velocity, such as with pellet gunshots; or low velocity, such as with stab wounds. Penetrating chest injuries have a higher mortality rate than blunt chest injuries but are less common. Performing the standardized trauma evaluation (primary and secondary surveys), as well as ordering proper imaging, is critical to determining the diagnosis and aiding in management decisions. The majority of PCIs do not require major surgery and can be managed by observation or tube thoracostomy, although surgical repair of injuries may be needed.
Transposition of the great vessels (TGV) is a cyanotic congenital heart disease characterized by “switching” of the great arteries. There are 2 presentations: the dextro (D)- and levo (L)-looped forms. The L-looped form is rare and congenitally corrected, as the ventricles are also switched. The D-looped form accounts for 3% of all cases of congenital heart disease. The condition occurs within the neonatal phase of life with cyanosis that is unresponsive to oxygen therapy. Diagnosis is confirmed by echocardiogram and a chest X-ray showing the classic “egg on a string” pattern. Treatment is primarily surgical, and the prognosis for surgically corrected cases is good.
Foreign body aspiration can lead to choking and death by obstructing airflow at the larynx or trachea. Foreign bodies may also become lodged deeper in the bronchi; this may not affect breathing but can cause infection or erosion of bronchial walls. Foreign bodies (FBs) are more frequently aspirated by children, who may present with coughing or wheezing. As FBs are rarely visible on X-ray, other modalities of imaging, such as computed tomography or flexible bronchoscopy, must be employed when prompted by symptoms and clinical suspicion. The relative frequency with which various objects are aspirated varies based on patient demographics. Prompt removal of the FB is the definitive treatment.
Flail chest is a life-threatening traumatic injury that occurs when 3 or more contiguous ribs are fractured in 2 or more different locations. Patients present with chest pain, tachypnea, hypoxia, and paradoxical chest wall movement. Management includes oxygen supplementation, pain control, ventilation if respiratory failure presents, and possible surgery. Severe traumatic intrathoracic injuries, such as pulmonary contusions, pneumothorax, and cardiac injuries, are often seen in conjunction with flail chest.
Atrial septal defects (ASDs) are benign acyanotic congenital heart defects characterized by an opening in the interatrial septum that causes blood to flow from the left atrium (LA) to the right atrium (RA) (left-to-right shunt). Atrial septal defects account for approximately 15% of all cases of congenital heart disease (CHD), making ASDs the 2nd most common CHD. There are 4 types of ASD based on the location of the defect along the atrial septum, but the most common is the ostium secundum defect. Atrial septal defects are usually detected during a routine physical examination and confirmed by an echocardiogram. In infancy, most small ASDs close spontaneously by 2 years of age. Only patients that are symptomatic require surgical closure. In general, most patients with ASD can expect a good overall outcome.
Aromatase deficiency is a very rare genetic condition with autosomal recessive inheritance. Aromatase deficiency is characterized by congenital estrogen deprivation with increased levels of testosterone due to decreased levels of the aromatase enzyme. Affected females present with abnormal development of the external genitalia, virilization, primary amenorrhea, and tall stature. Males usually develop symptoms later in life, including hyperinsulinemia and lipid metabolism disorders. Individuals affected by aromatase deficiency have an increased risk of developing osteoporosis. Treatment involves hormone replacement therapy.
Reactive arthritis is a seronegative autoimmune spondyloarthropathy that occurs in response to a previous gastrointestinal (GI) or genitourinary (GU) infection. The pathophysiology of this disease is unclear, but a significant proportion of affected patients are positive for HLA-B27. The disease manifests as asymmetric oligoarthritis (particularly of large joints in the lower extremities), enthesopathy, dactylitis, and/or sacroiliitis. Ocular, mucocutaneous, GI, GU, and cardiac manifestations may also occur. The diagnosis is clinical, and efforts should be made to rule out alternative diagnoses. Management focuses on controlling symptoms, typically with nonsteroidal anti-inflammatory drugs. An active infection should also be treated, particularly Chlamydia trachomatis.
The plague is a bacterial infection caused by Yersinia pestis (Y. pestis), which primarily infects rodents. The disease is transmitted to humans via a fleabite. Inhalation of infectious droplets and handling infected animals or laboratory specimens are other means of transmission. The plague has 3 forms: bubonic (most common form), septicemic, and pneumonic. Bubonic plague results in swollen and tender lymph nodes called buboes in the inguinal area. Pneumonic and septicemic plague can arise as the primary presentation, but also can result from hematogenous spread from the bubonic disease. Diagnosis includes clinical history and findings, culture, polymerase chain reaction (PCR), and serology. The mortality rate is high, so prompt diagnosis and treatment with antibiotics are necessary.
Osgood-Schlatter disease, or apophysitis of the tibial tubercle, is a common orthopedic condition seen in children between 10 and 15 years of age. The disease is caused by the repetitive application of mechanical forces on the knee, leading to microtrauma on the ossification center at the site of insertion of the distal patellar ligament. Patients present with localized knee pain, tenderness, and swelling at the proximal anterior tibia. Diagnosis is clinical and treatment is focused on symptomatic relief. Osgood-Schlatter disease is a self-limiting condition that resolves with skeletal maturity.
Slipped capital femoral epiphysis (SCFE) is an orthopedic disorder of early adolescence characterized by the pathologic “slipping” or displacement of the femoral head, or epiphysis, on the femoral neck. Considered a type I Salter-Harris growth plate fracture, SCFE affects boys twice as often as girls. Thought to be due to a combination of biomechanical and endocrine factors, diagnosis is made with hip X-rays and treatment ranges from conservative to surgical. Prognosis depends on the severity of the slip or displacement.
Injuries due to cold weather are common among children and athletes who are involved in sports played in cold conditions. There are multiple cold-related injuries, with frostbite being the most common. Frostbite is a direct freezing injury to the peripheral tissues and occurs when the skin temperature drops below 0℃ (32°F). Common sites of frostbite include the nose, ears, fingers, and toes. Clinical signs include skin pallor, anesthesia, blistering, and tissue necrosis. The main treatment is rapid rewarming.
Scleroderma (systemic sclerosis) is an autoimmune condition characterized by diffuse collagen deposition and fibrosis. The clinical presentation varies from limited skin involvement to diffuse involvement of internal organs. Diagnosis is established by a combination of physical findings and serology. There is no curative treatment. Management options are limited and include immunosuppressive medications as well as specific organ- or symptom-directed drugs. The overall 5-year survival of patients with scleroderma is about 80%.
The apophysis is a secondary ossification center found on non-weight-bearing segments of bones. The apophysis is also the site of ligament or tendon insertion and is involved in the peripheral growth of the bone. These secondary growth centers are generally open in late childhood and may not close until early adulthood. With overuse, the apophysis may become inflamed and painful, becoming vulnerable to tearing and avulsion. An acute apophyseal avulsion fracture occurs when a portion of the apophysis is pulled off by the ligament, usually secondary to explosive movements and eccentric muscular contractions. Apophyseal avulsion fractures are primarily treated conservatively, but may require surgical repair if the avulsed fragment is large or significantly displaced.
The bones of growing children exhibit unique characteristics, which, combined with the unique mechanisms of injury seen in children, result in fracture patterns differing significantly from those common in adults. The greenstick fracture is an incomplete fracture usually seen in long bones. The bone is typically bent, and the fracture extends only partway through the bone. Greenstick fractures are at high risk for refracture and should be completely immobilized. Greenstick fractures rarely require reduction but should be managed cautiously to prevent malunion or angulation deformities. A patient with a greenstick fracture should be referred for orthopedic follow-up.
A “toddler’s fracture” is a spiral or oblique fracture of the distal tibia in toddlers resulting from a low-energy trauma with a rotational/twisting component. These fractures are often seen in children who are learning to walk and who do not have a specific history of trauma. The child can sometimes present with a painful limp or refusal to bear weight on the affected limb. Management comprises analgesia and immobilizing the injured leg for several weeks.
Antiretroviral therapy (ART) targets the replication cycle of the human immunodeficiency virus (HIV) and is classified based on the viral enzyme or mechanism that is inhibited. The goal of therapy is to suppress viral replication to reach the outcome of undetected viral load. Currently, reverse transcriptase, protease, integrase, and entry inhibitors are used in combined ART (cART) regimens. Combination therapy (3-drug regimen) is used to prevent drug resistance and cross-resistance, which develop through genetic mutations.
The bones of growing children exhibit unique characteristics. These characteristics, combined with the unique mechanisms of injury seen in children, result in fracture patterns that differ significantly from those that are common in adults. When axial loads are applied, particularly to long bones in children, compressive forces may result in buckling of the bone without disruption of the periosteum. These fractures are called buckle or torus fractures and are considered generally stable, requiring only immobilization.
A gastrinoma is a tumor that secretes excessive levels of the hormone gastrin and is responsible for Zollinger-Ellison syndrome (ZES). Gastrinomas are frequently associated with multiple endocrine neoplasia 1 (MEN 1) and can arise from the pancreas, stomach, duodenum, jejunum, and/or even from the lymph nodes. Gastrinoma tumors are often malignant and frequently metastasize to the liver, lymph nodes, and bone. Zollinger-Ellison syndrome (ZES) is characterized by high gastrin levels, elevated gastric acid production, peptic ulcers, gastroesophageal reflux, and diarrhea. Diagnosis is based on fasting serum gastrin levels. Management consists of surgical resection of the gastrinoma and/or symptomatic management for unresectable disease.
Chlamydial infections are a group of infectious diseases caused by bacteria belonging to the Chlamydiaceae family. The 3 species that can infect humans are Chlamydia trachomatis, C. pneumoniae, and C. psittaci. The most common infection is an STI caused by C. trachomatis, which affects the genitourinary tract. Chlamydia is the most common sexually transmitted bacterial infection in the United States. Other species of Chlamydia mainly cause respiratory infections. Diagnosis is based on nucleic acid amplification tests. Management is with antibiotics. Untreated chlamydial infections may have serious consequences, including sterility, ectopic pregnancies, spontaneous abortions, and chronic pelvic inflammatory disease.
Tricuspid valve atresia (TVA) is a congenital heart defect (CHD) causing an absent or rudimentary tricuspid valve (TV) associated with an interatrial or ventricular septal defect. Patients present with cyanosis at birth due to blood mixing between the right atrium (RA) and right ventricle (RV). Diagnosis can be made in utero or confirmed after birth with an echocardiogram. Definitive management involves a staged surgical procedure beginning in the neonatal period.
Total anomalous pulmonary venous return (TAPVR) is a cyanotic congenital heart defect wherein the pulmonary veins drain into anatomical sites other than the left atrium. The most common sub-type is the supra cardiac form, where the drainage is into the superior vena cava. Patients are usually cyanotic from birth and present with respiratory and heart failure right after birth. On examination there is a fixed, wide split-second heart sound, and a chest X-ray might reveal the “snowman” sign. Diagnosis is confirmed by an echocardiogram, which can be prenatal. All patients require surgery for survival and medical management is used to bridge the gap to surgery.
Serotonin syndrome is a life-threatening condition caused by large increases in serotonergic activity. This condition can be triggered by taking excessive doses of certain serotonergic medications or taking these medications in combination with other drugs that increase their activity. Hallmarks of this condition are autonomic hyperactivity, neuromuscular instability, and altered mental status. Management involves discontinuation of all serotonergic agents, sedation with benzodiazepine, and cyproheptadine (a serotonin antagonist) if supportive measures fail.
A volvulus is the twisting or axial rotation of a portion of the bowel around its mesentery. The most common site of volvulus in adults is the colon; most frequently the sigmoid volvulus. Patients typically present with symptoms of bowel obstruction such as abdominal pain, distension, vomiting, and constipation/obstipation. In severe cases, signs of bowel ischemia and gangrene (tachycardia, hypotension, hematochezia, and peritonitis) may also be present. Clinical suspicion prompts imaging to confirm the diagnosis and surgery is the definitive treatment. For stable patients with sigmoid volvulus, surgery may be preceded by endoscopic detorsion. However, immediate surgery is required for colon perforation or ischemia.
A VIPoma is a rare neuroendocrine tumor arising primarily in the pancreas that releases large amounts of vasoactive intestinal polypeptide (VIP). This process leads to chronic watery diarrhea with concomitant hypokalemia and dehydration, as well as wheezing and flushing (known as Verner-Morrison or WDHA (chronic Watery Diarrhea, Hypokalemia, Achlorhydria) syndrome). Most tumors arise sporadically, but some are associated with MEN 1. Diagnosis is established by measuring serum VIP levels. Treatment consists of medical management of symptoms and complete surgical removal of the tumor when possible.
IgA nephropathy (Berger's disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. Common presenting features are gross hematuria or asymptomatic, microscopic hematuria on urinalysis. The course is often benign, with the definitive diagnostic procedure, renal biopsy, performed only in cases of severe, progressive renal disease. Treatment depends on the severity of proteinuria, renal function, and pathologic changes. ACE inhibitors or angiotensin-receptor blockers (ARBs) are given to reduce disease progression. Persistent proteinuria and increasing creatinine are indications for immunosuppressive therapy that includes glucocorticoids and, possibly, cytotoxic agents.
Sick sinus syndrome (SSS), also known as sinus node dysfunction, is characterized by degeneration of the sinoatrial (SA) node, the heart’s primary pacemaker. Patients with SSS may be asymptomatic or may present with tachycardia or bradycardia. In cases of bradycardia, patients can experience fatigue, light-headedness, and syncope. Diagnosis is made by physical exam and ECG. Management can include a pacemaker.
Supracondylar fractures are the most common elbow fractures in the pediatric population. The most common mechanism of injury involves a fall on an outstretched hand, resulting in a fracture of the distal humerus. Patients frequently present with pain, visible deformity, and limited range of motion of the injured elbow. This fracture often requires immediate orthopedic consultation secondary to the displacement of the fracture and the frequency of concomitant neurovascular injury.
Prostate cancer is one of the most common cancers affecting men. In the United States, the lifetime risk of being diagnosed with prostate cancer is approximately 11%, and the lifetime risk of death is 2.5%. Prostate cancer is a slow-growing cancer that takes years, or even decades, to develop into advanced disease. Several men with prostate cancer are asymptomatic. Late-stage cancer can present with bone pain, urinary symptoms, and/or weight loss. Most cases of prostate cancer are identified based on diagnostic tests to determine prostate-specific antigen (PSA) levels and are confirmed based on image-guided transrectal biopsy. Management of prostate cancer depends on age, life expectancy, comorbidities, risk stratification, and preferences of the patient. Management options include active surveillance, androgen deprivation therapy, radiotherapy, chemotherapy, and radical prostatectomy.
Uterine leiomyomas (or uterine fibroids) are benign tumors arising from smooth muscle cells in the uterine myometrium. Leiomyosarcomas, however, are malignant tumors, arising de novo (not from fibroids). With a lifetime risk of > 70% for both African American and Caucasian women, fibroids are common. Conversely, leiomyosarcomas are rare. Leiomyosarcomas may present similarly to uterine fibroids making preoperative diagnosis challenging. Both conditions present with abnormal bleeding, pelvic pain, and/or bulk symptoms. A fibroid is identified as a hypoechoic, well-circumscribed, round mass on pelvic ultrasound. A leiomyosarcoma is usually diagnosed on a postoperative specimen. Depending on patient symptoms and preference, treatment for leiomyoma may include surgical resection or medical options to reduce bleeding and/or bulk. Management of leiomyosarcoma, which carries a poor prognosis, may include adjuvant chemotherapy based on stage.
Dilated cardiomyopathy (DCM) is the most common type of non-ischemic cardiomyopathy and a common cause of heart failure (HF). The cause may be idiopathic, familial, or secondary to a variety of underlying conditions. The disease is characterized by the enlargement of 1 or both ventricles and reduced systolic function. Patients typically present with symptoms of HF such as shortness of breath, fatigue, weakness, and peripheral edema. Blood tests, ECG, X-rays, echocardiography, and other cardiac studies and procedures are typically done to obtain the diagnosis. Treatment includes medications used to reduce volume overload (e.g., diuretics) and manage HF (e.g., beta-blockers). Devices such as pacemakers and cardioverter-defibrillators may also be needed. In severe cases, a heart transplant is required. Complications include thromboembolic events and sudden cardiac death.
Nephritic syndrome is a renal condition with signs and symptoms produced by inflammation of the glomeruli (glomerulonephritis) and increased permeability of the glomerular barriers. Defining features include hematuria, proteinuria (but below nephrotic range), RBC casts with dysmorphic RBCs on urine microscopy, and increased serum creatinine. Causes can be genetic, autoimmune, idiopathic, or post-infectious. The most common cause is acute post-streptococcal glomerulonephritis. General clinical findings include edema, hypertension, and oliguria. Diagnosis is made based on history, physical exam, and laboratory data. A renal biopsy is sometimes necessary to establish the underlying cause. There can be a combined nephritic-nephrotic picture, especially in the chronic presentation. Treatment and prognosis depend on cause and severity.
Lentigo maligna is melanoma in situ, a precancerous lesion that may progress to an invasive melanoma (specifically lentigo maligna melanoma subtype). This condition typically occurs in sun-damaged areas (e.g., face and neck) of elderly patients. Lentigo maligna presents as a brown macule with color variegation and asymmetrical borders that grow slowly. The lesion should be biopsied to confirm a diagnosis and surgical excision with a safety margin is the 1st-line treatment.
Opioid use disorder (OUD) is a substance use disorder characterized by pathologic consumption of opioids. Opioids are central nervous system depressants that are used medically as potent analgesics. However, they are often misused for their euphoric effects. Features of opioid intoxication include respiratory depression, drowsiness, and pinpoint pupils. Intoxication can be managed with administration of naloxone. If discontinued, patients may develop withdrawal symptoms such as irritability, piloerection, and stomach cramps. Withdrawal may be managed by methadone or buprenorphine. Chronic OUD is managed with psychotherapy as well as medications. Prognosis is poor without adequate management and prevention of relapse and overdose.
Alport syndrome, also called hereditary nephritis, is a genetic disorder caused by a mutation in the genes encoding for the alpha chains of type IV collagen, resulting in the production of abnormal type IV collagen strands. Patients present with glomerulonephritis, hypertension, edema, hematuria, and proteinuria, as well as with ocular (cataract, retinopathy) and auditory (sensorineural hearing loss) findings. Diagnosis is established with urinalysis, urine microscopy, and a renal function panel. A renal biopsy showing characteristic glomerular basement membrane splitting may be used to confirm the diagnosis. Treatment for Alport syndrome is focused on limiting disease progression with angiotensin receptor blockers and angiotensin-converting enzyme inhibitors. Hearing aids are used for hearing loss associated with Alport syndrome.
Chorioamnionitis, commonly referred to as intraamniotic infection (IAI), is a common obstetric complication involving infection and inflammation of the fetal membranes, amniotic fluid, placenta, or the fetus itself. Chorioamnionitis is typically caused by a polymicrobial infection that ascends from the lower genitourinary tract. Primary risk factors include prolonged rupture of membranes and prolonged labor. Chorioamnionitis is diagnosed by clinical findings, including maternal fever. Chorioamnionitis is managed with antibiotics, and by ensuring continued labor progress (or initiating progress) toward delivery. Chorioamnionitis typically resolves soon after delivery. Significant maternal and fetal complications are possible, warranting prompt diagnosis and treatment.
Endometrial polyps are pedunculated or sessile projections of the endometrium that result from overgrowth of endometrial glands and stroma around a central vascular stalk. Endometrial polyps are a few millimeters to a few centimeters in size, can occur anywhere within the uterine cavity, and, while usually benign, can be malignant, particularly in postmenopausal women. Endometrial polyps present with abnormal uterine or postmenopausal bleeding, although many are asymptomatic and discovered incidentally. Endometrial polyps are best diagnosed with a saline-infusion sonogram, and are usually treated with hysteroscopic resection.
Carotid artery stenosis is a chronic atherosclerotic disease resulting in narrowing of the common and internal carotid arteries. Common risk factors include family history, advanced age, hyperlipidemia, smoking, and diabetes mellitus. Patients may present with or without symptoms of decreased cerebral perfusion. Carotid artery stenosis is commonly diagnosed via ultrasound. Management includes lifestyle modifications to control progression of atherosclerosis. Treatment is with statins, anti-hypertensive and antiplatelet agents, and, in some cases, surgical revascularization. The most serious complication of carotid artery stenosis is stroke.
Secondary amenorrhea is defined as the absence of menses for 3 months in a woman with previously regular menstrual cycles or for 6 months in a woman with previously irregular cycles. Etiologies involve either disruptions to the hypothalamic–pituitary–ovarian (HPO) axis or acquired obstructions in the uterus or outflow tract. The most common cause of secondary amenorrhea is pregnancy. The most common pathologic etiologies include functional hypothalamic amenorrhea, polycystic ovary syndrome, hyperprolactinemia, premature ovarian insufficiency, and Asherman's syndrome. The diagnosis is made with a thorough history and physical examination, measurement of hormone levels, a pregnancy test, and imaging with pelvic ultrasonography. A progestin and/or combined estrogen–progestin challenge can help further identify the location of the abnormality. Management depends on the underlying etiology, clinical presentation, and patient desires regarding fertility. Treatment can include lifestyle, medical, and surgical management options.
Appendectomy is an invasive surgical procedure performed with the goal of resecting and extracting the vermiform appendix through either an open or a laparoscopic approach. The most common indication is acute appendicitis, which is why appendectomies are usually carried out in an urgent fashion. It is one of the most commonly performed emergent abdominal procedures. It can be associated with a number of postoperative complications; however, the majority of patients do very well and recover quickly.
Amyloidosis is a disease caused by abnormal extracellular tissue deposition of fibrils composed of various misfolded low-molecular-weight protein subunits. These proteins are frequently byproducts of other pathological processes (e.g., multiple myeloma). These misfolded proteins can become deposited in different tissues, interfere with normal organ functions, and cause tissue-specific diseases (e.g., renal amyloidosis causes proteinuria). Diagnosis is established clinically and confirmed with tissue biopsy. Treatment should be directed toward the underlying cause and the reduction of amyloid deposition.
Preterm labor refers to regular uterine contractions leading to cervical change prior to 37 weeks of gestation; preterm birth refers to birth prior to 37 weeks of gestation. Preterm birth may be spontaneous due to preterm labor, preterm prelabor rupture of membranes (PPROM), or cervical insufficiency. Preterm birth may also be initiated by the provider for a variety of maternal or fetal indications. Diagnosis involves assessments to detect cervical change and monitoring for regular uterine contractions. Management depends on gestational age, but typically includes administration of corticosteroids (to improve fetal lung maturity), magnesium sulfate (for fetal neuroprotection against cerebral palsy), group B streptococcus (GBS) prophylaxis, and 48 hours of tocolytics to help patients complete a full course of steroids.
Chancroid is a highly transmissible STD caused by Haemophilus ducreyi. The disease presents with painful ulcer(s) on the genital tract (termed chancroid or “soft chancre”). Up to 50% of patients will develop painful inguinal lymphadenopathy. Furthermore, of that percentage, 25% may develop complications of the suppurative lymph nodes. Given the growth of H. ducreyi on a special medium (often not readily available), chancroid is diagnosed based upon clinical appearance and tests to rule out both syphilis and herpes (the most common causes of genital ulcers). Although the disease can resolve spontaneously, antibiotics (azithromycin or ceftriaxone) are the treatment of choice. Treatment should involve both patients and their sexual contacts.
A brief resolved unexplained event (BRUE) is defined as a reported, sudden, brief (< 1 minute) event in a child < 1 year of age, which is resolved at the time of presentation. The definition includes ≥ 1 finding of either change in color (cyanosis or pallor), breathing pattern (absent, decreased, or irregular), muscle tone (hypertonia or hypotonia), or level of consciousness. The findings are based on a report given by a parent or caregiver. Adopted by the American Academy of Pediatrics in 2016, the new term was to replace the previously used terms “apparent life-threatening event” (ALTE) and “near sudden infant death syndrome”. The change in terminology was to better define an unexplained event after a thorough evaluation, stratify high- and low-risk groups, identify those needing further evaluation, and avoid unnecessary testing and admissions. Importantly, BRUE can be diagnosed only if there is no other explanation for the episode after a careful history and physical examination.
Restrictive cardiomyopathy (RCM) is a fairly uncommon condition characterized by progressive stiffening of the cardiac muscle, which causes impaired relaxation and refilling of the heart during diastole, resulting in diastolic dysfunction and eventual heart failure. It most often occurs secondary to scarring, damage, and/or infiltration of the heart muscle, with amyloidosis being the most common cause. Infrequently, it may be idiopathic or inherited. Signs and symptoms include shortness of breath, low exercise tolerance, fatigue, and peripheral edema. Diagnosis is made through clinical suspicion and confirmed through ECG, X-ray, echocardiography, and cardiac MRI. Treatment includes medications for heart failure, implantable devices such as pacemakers and cardioverter–defibrillators, and heart transplantation in refractory cases.
Caustic agents are acidic or alkaline substances that damage tissues severely if ingested. Alkali ingestion typically damages the esophagus via liquefactive necrosis, whereas acids cause more severe gastric injury leading to coagulative necrosis. Ingestion of large volumes and high concentrations of caustic agents can lead to severe and extensive injuries. Additionally, aspiration affects the laryngeal and tracheobronchial structures. Signs and symptoms include oral pain, burns, dysphagia, vomiting, and abdominal pain. Severe injuries can present with shock, abdominal rigidity, respiratory distress, and/or altered mental status. Diagnosis is based on laboratory tests, abdominal and chest imaging, and endoscopy within 24 hours (if without contraindications) to determine the extent of damage. Management involves stabilizing the cardiorespiratory status, decontamination, and supportive therapy. Severe injury may require surgery.
Cannabis use disorder (CUD) is characterized by the pathologic consumption of cannabis, which is the most commonly used illicit substance worldwide. While cannabis has some beneficial medical uses, it also has the potential to cause intoxication characterized by psychosis or cognitive impairment, especially in chronic use. Unlike most other substances, withdrawal symptoms are mild. There is currently no strong evidence for long-term benefits of pharmacologic or psychosocial interventions in the management of cannabis use disorder. Other factors such as underlying mood or personality disorders or comorbidity with other substance use disorders are associated with a poor prognosis.
In the context of acute or chronic kidney failure, renal function may diminish to a point at which it is no longer able to adequately support life. When this happens, renal replacement therapy is indicated. Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD).
Lactose intolerance (LI) describes a constellation of symptoms due to lactase deficiency (LD), the enzyme located in the brush border of the adsorptive cells in the small intestine. Lactose is the disaccharide present in milk and requires hydrolysis by lactase to break it down into its 2 absorbable constituents, glucose and galactose. Lactose intolerance typically presents with bloating, abdominal cramping, diarrhea, and flatulence. The diagnosis of LI can be suspected clinically based on symptoms after consumption of a lactose-containing meal. The most commonly used test for confirmation of the diagnosis is the lactose hydrogen breath test. The treatment goal is to eliminate symptoms while maintaining sufficient intake of calcium and vitamin D. Alternative diagnoses to LI should always be sought, as many people wrongly attribute their symptoms to LI.
The kidneys are primarily in charge of the maintenance of water and solute homeostasis through the processes of filtration, reabsorption, secretion, and excretion. Glomerular filtration is the process of converting the systemic blood supply into a filtrate, which will ultimately become the urine. Complex regulatory processes ensure that only the appropriate substances in the systemic blood are lost in the urine and that the urine flow is satisfactorily balanced to maintain adequate systemic volume status. Abnormalities of the glomerulus can cause several clinically important conditions.
Bariatric surgery refers to a group of invasive procedures used to surgically reduce the size of the stomach to produce early satiety, decrease food intake (restrictive type) and/or alter digestion, and artificially induce malabsorption of nutrients (malabsorptive type). The ultimate goal of bariatric surgery is drastic weight loss. Bariatric surgery is currently the only modality that provides significant long-term weight loss in morbidly obese individuals and cures or significantly improves obesity-related complications. The 2 modalities currently in wide use are the Roux-en-Y gastric bypass and sleeve gastrectomy.
Extranodal marginal zone lymphoma (EMZL) of mucosa-associated lymphoid tissue (also called MALToma, MALT lymphoma, and pseudolymphoma) is a group of non-Hodgkin’s lymphomas that have historically been grouped together because they appear to arise from postgerminal center marginal zone B cells and share a similar immunophenotype. MALT lymphoma is thought to arise in the setting of chronic immune stimulation, which is usually due to bacterial, viral, or autoimmune stimuli. MALT lymphomas present with symptoms due to localized involvement of glandular epithelial tissues in the specific site where they develop. Diagnosis of MALT lymphoma is made by morphologic, immunophenotypic, and genetic analysis of biopsy samples. Helicobacter pylori–positive gastric MALT lymphoma is treated with H. pylori eradication therapy, and H. pylori–negative gastric MALT lymphoma is treated with radiation therapy. Nongastric MALT lymphoma is treated based on the involved area and extent of disease. MALT lymphoma patients have a good prognosis, with a median survival of > 10 years.
Hyperparathyroidism is a condition associated with elevated blood levels of parathyroid hormone (PTH). Depending on the pathogenesis of this condition, hyperparathyroidism can be defined as primary, secondary or tertiary. Primary hyperparathyroidism is an inherent disease of parathyroid glands associated with abnormal secretion of PTH. Secondary hyperparathyroidism results from abnormalities of calcium metabolism, which, if left untreated, can progress to tertiary hyperparathyroidism, which is associated with hypertrophy of the parathyroid gland and oversecretion of PTH even if the primary cause is eliminated. Diagnosis is based on biochemical parameters, which include serum PTH, calcium, and phosphate levels as well as urinary calcium. Management relies mostly on surgical parathyroidectomy for primary and tertiary hyperparathyroidism. Management of secondary hyperparathyroidism is focused on treatment of the underlying disease.
Potassium is the main intracellular cation in all cells and is distributed unevenly between the intracellular fluid (98%) and extracellular fluid (2%). This large disparity is necessary for maintaining the resting membrane potential of cells, and explains why K+ balance is tightly regulated. The GI tract secretes 5%–10% of the absorbed K+ daily; however, the kidneys are responsible for 90%–95% of the overall K+ regulation. While most of the K+ is reabsorbed in the proximal tubules, the majority of regulation occurs in the principal and α-intercalated cells of the collecting ducts. The most important regulatory mechanisms include aldosterone, plasma K+ concentration, distal urinary flow rate, and the distal delivery of Na+ and water. Hyperkalemia and hypokalemia can result when K+ regulation is abnormal.
Dog and cat bites can cause superficial and deep tissue destruction, as well as serious wound infections. Dog bites occur more frequently in men and children and often cause crushing or tearing trauma. Cat bites are more frequent in adult women and result in puncture wounds. Because puncture wounds allow inoculation of bacteria into the deep tissues, cat bites are more frequently associated with infection. The diagnosis is clinical, and cultures should be obtained if the wound appears infected. Management requires fastidious wound care and antibiotics for high-risk or infected wounds.
Hydrogen cyanide is an extremely poisonous, colorless, flammable liquid used in multiple industries and includes rubber, plastic, and household paints. Exposure to cyanide can occur via inhalation, dermal contact, or intestinal ingestion. Cyanide poisoning is a common complication of closed-space fires since cyanide is a byproduct of plastics combustion. Symptoms develop within seconds to minutes and involve cardiovascular, respiratory, and neurological changes. Management includes sodium thiosulfate, nitrites, and hydroxocobalamin. If not recognized and treated promptly, cyanide poisoning is frequently lethal.
Basic surgical intervention in the thoracic cavity has the primary goal of alleviating any malady that mechanically affects the function of the heart and lungs, which can be secondary to underlying pathologies or, most commonly, trauma. Interventions such as tube thoracostomy and thoracentesis are performed to evacuate fluid, blood, or air that is occupying the thoracic cavity in order to restore thoracic negative pressure. When direct intervention to the heart and mediastinum is required, an emergency thoracotomy is performed. Once the immediate mechanical problems are addressed, more advanced reparative surgery involving heart, lungs, or mediastinal structures can then be performed as necessary.
Edwards syndrome, or trisomy 18, is a genetic syndrome caused by the presence of an extra chromosome 18. The extra chromosome is either from 3 full copies of chromosome 18 or an additional segment of chromosome 18. As the 2nd most common trisomy, Edwards syndrome is seen in 1 out of every 5,500 live births and increases with maternal age. Many cases are detected prenatally with maternal screening and ultrasound findings. Abnormalities include intrauterine growth restriction (IUGR), overlapping fingers, typical craniofacial features, rocker-bottom feet, and congenital heart defects. Trisomy 18 frequently results in fetal loss. For term pregnancies, most deaths occur during the 1st 6 months of life. Delivery in a specialized center is recommended for full-term pregnancies and intervention is based on associated abnormalities.
A pyogenic liver abscess is a polymicrobial infection arising from contiguous or hematogenous spread. Pyogenic liver abscess is the most common type of visceral abscess. Patients may present with a triad of fever, malaise, and RUQ pain. Laboratory analysis can be informative with elevated WBC and abnormal liver function tests, and imaging may reveal solitary or multiple lesions on ultrasound or CT scan. On contrast imaging, the lesions generally appear well defined with rim enhancement. Diagnosis requires aspiration with Gram stain and culture and, in some cases, a drainage catheter may be placed. A combination of drainage and IV antibiotic therapy is the primary method of treatment. Surgical drainage or resection is utilized in specific cases.
Trisomy 13, or Patau syndrome, is a genetic syndrome caused by the presence of 3 copies of chromosome 13. As the 3rd most common trisomy, Patau syndrome has an incidence of 1 in 10,000 live births and is more common in women. Most cases of Patau syndrome are diagnosed prenatally by maternal screening and ultrasound. More than half of the pregnancies result in spontaneous abortions. If pregnancy reaches term, it is recommended that a specialized center handle delivery and neonatal care. In the neonate, findings include craniofacial and cardiac malformations, severe intellectual disability, and greatly reduced life expectancy. Most babies do not survive beyond 3 months. With no treatment available and a null expectancy of survival, the family is given supportive management and resources to navigate through the natural course of the disease.
Cholecystectomy is a surgical procedure performed with the goal of resecting and extracting the gallbladder. It is one of the most common abdominal surgeries performed in the Western world. Cholecystectomy is performed for symptomatic cholelithiasis, cholecystitis, gallbladder polyps > 0.5 cm, porcelain gallbladder, choledocholithiasis and gallstone pancreatitis, and rarely, for gallbladder cancer. Over 90% of cholecystectomies are now completed laparoscopically because of the procedure’s enhanced recovery time and decreased postoperative pain. Cholecystectomy has a low-risk profile, but the most dreaded complications include vascular and biliary ductal injuries.
Bowen disease and erythroplasia of Queyrat are 2 related entities that describe squamous cell carcinoma (SCC) in situ of the skin. Bowen disease usually presents in sun-exposed areas (e.g., face and forearms) as a red, scaly skin lesion. The lesion can occur in other areas as well. The genital region, particularly the penile shaft, is also affected. When the glans penis is involved, the lesion is called erythroplasia of Queyrat, with uncircumcised males being at high risk. Both genital lesions have HPV infection as a risk factor. Pathologic findings show full-thickness atypia without basement membrane invasion. Both entities may progress to invasive SCC. Thus, local destruction via surgical excision or topical chemotherapy should be performed.
Bowenoid papulosis is a sexually transmitted condition induced by HPV infection, which facilitates keratinocyte neoplastic transformation. On skin biopsy, Bowenoid papulosis manifests as low-grade dysplasia. Affected individuals present with genital papules of a red-to-brown color that are often asymptomatic. Although most cases resolve spontaneously, lesions should be followed up because there is a risk of transformation to invasive squamous cell carcinoma (SCC). Cryosurgery, excision, or topical therapy may be used to hasten the resolution of persistent cases of Bowenoid papulosis.
Polycystic kidney disease (PKD) is an inherited genetic disorder leading to the development of numerous fluid-filled cysts in the kidneys. The 2 main types of PKD are autosomal recessive polycystic kidney disease (ARPKD), which is often diagnosed antenatally or shortly after birth, and autosomal dominant polycystic kidney disease (ADPKD), which is often diagnosed in adulthood. Autosomal recessive polycystic kidney disease is primarily characterized by cystic dilatations of the renal collecting ducts and intrahepatic bile duct dilatation with hepatic fibrosis. Diagnosis is through physical exam and ultrasonography. Management requires a multidisciplinary approach to slow the progression of renal disease by controlling hypertension, proteinuria, and symptoms. The prognosis of ARPKD depends on the age at presentation, along with the degree of hepatic and renal involvement. Patients progressing to end-stage renal disease (ESRD) will need renal replacement therapy.
Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Diagnosis of meningitis is made on clinical grounds with a thorough neurologic examination. CSF analysis is an important diagnostic tool, as it is difficult to identify the exact cause clinically. Management of meningitis includes immediate broad-spectrum antibiotics and supportive therapy to prevent complications. Specific treatment depends on the etiology of meningitis. Delay in treatment can lead to permanent neurologic defects and death.
Hypernatremia is an elevated serum sodium concentration > 145 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled by the hypothalamus via the thirst mechanism and antidiuretic hormone (ADH) release. Hypernatremia occurs either from a lack of access to water or an excessive intake of sodium. The total volume of water lost (usually via GI or renal routes) is regained through normal oral intake. Therefore, if a patient has access to water and an intact thirst mechanism, many etiologies of hypernatremia may remain hidden. The etiology of hypernatremia is often easily determined by clinical history. Treatment is primarily a replacement of the free water deficit by IV or oral routes.
Amebiasis, or amoebic dysentery, is an infection caused by the parasite Entamoeba histolytica. Transmission is through the fecal-oral route or by consumption of contaminated food and water. Most patients infected with E. histolytica are asymptomatic, but about 10% may develop dysentery. Invasive infections are characterized by abdominal pain, fever, and bloody diarrhea, and can lead to serious complications including liver abscesses, intestinal fistulas, or fulminant colitis. Diagnosis is usually made based on stool studies or the detection of immunologic markers. Treatment consists of both an absorbable amebicidal agent such as metronidazole and an intraluminal amebicidal agent such as paromomycin.
Since human cells are primarily reliant on aerobic metabolism, it is of vital importance to efficiently obtain oxygen from the environment and bring it to the tissues while excreting the byproduct of cellular respiration (CO2). Respiration involves both the respiratory and circulatory systems. There are 4 processes that supply the body with O2 and dispose of CO2. The respiratory system is involved in pulmonary ventilation and external respiration, while the circulatory system is responsible for transport and internal respiration. Pulmonary ventilation (breathing) represents movement of air into and out of the lungs. External respiration, or gas exchange, is represented by the O2 and CO2 exchange between the lungs and the blood.
Electrolytes are mineral salts that dissolve in water and dissociate into charged particles called ions, which can be either be positively (cations) or negatively (anions) charged. Electrolytes are distributed in the extracellular and intracellular compartments in different concentrations. Electrolytes are essential for various basic life-sustaining functions such as maintaining electrical neutrality in cells, generating action potentials in nerves and muscles, and maintaining normal blood pH. The most important electrolytes are sodium, potassium, chloride, magnesium, calcium, phosphate, and bicarbonate. In order for these electrolytes to participate in biochemical reactions and cellular processes, regulatory mechanisms are in place, which help maintain homeostasis.
Sexually transmitted infections (STIs) or sexually transmitted diseases (STDs) are infections that spread either by vaginal intercourse, anal sex, or oral sex. Symptoms and signs may include vaginal discharge, penile discharge, dysuria, skin lesions (e.g., warts, ulcers) on or around the genitals, and pelvic pain. Some infections can lead to infertility and chronic debilitating disease. And some STIs can affect infants by vertical transmission. Diagnosis of STIs includes a combination of comprehensive medical and sexual history, assessing risk factors, focused genitourinary physical exam, and disease-specific laboratory tests/cultures. Treatment and prevention include a combination of antibiotic/antiviral agents and patient education on safe sex practices.
Constipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency < 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic. Primary/functional constipation can be divided into normal transit, slow transit, and outlet constipation. Constipation is a symptom, not a disease, and appropriate management requires an evaluation of possible etiologies, such as systemic disorders and drugs. Once secondary causes have been eliminated, idiopathic constipation can be managed with lifestyle modifications and medications.
Thorough preoperative care is important for patients scheduled to undergo surgery so that they can have the best possible outcomes after their surgical procedure. The preoperative process begins once the decision has been made to proceed with a surgical procedure. In the case of elective surgeries, preoperative care is provided in an outpatient setting over several days to weeks prior to the surgery. For emergent surgeries, there may be limited time for preoperative evaluation and optimization in an inpatient setting. Preoperative assessment includes a thorough medical history, physical examination, risk assessment, and general and system-specific evaluations. The goal is to identify and address potential concerns prior to surgery and improve surgical outcomes.
Minimal change disease (MCD), also known as lipoid nephrosis, is the most common cause of nephrotic syndrome in children. The designation “minimal change” comes from the very little changes noticed in kidney biopsies under light microscopy. Hallmark clinical findings include edema, proteinuria, hypoalbuminemia, and hyperlipidemia. Diagnosis is based on clinical suspicion and supportive lab findings. Corticosteroid administration is the cornerstone of management, and the prognosis is largely favorable.
Intestinal ischemia occurs when perfusion fails to meet the demands of the intestines, resulting in ischemic tissue injury that can be life-threatening if bowel necrosis and/or perforation occurs. Symptoms can range from mild indigestion or diarrhea to severe abdominal pain. Imaging techniques including CT and angiography are used to detect stenosis or occlusion. The chronic form of intestinal ischemia benefits from medical therapies and revascularization procedures (stents, bypass surgery) while acute forms require urgent interventions to restore blood flow and remove any dead bowel tissue. Delay in the diagnosis and management of acute intestinal ischemia results in high mortality and severe complications, including intestinal perforation and sepsis.
Hypercalcemia (serum calcium > 10.5 mg/dL) can result from various conditions, the majority of which are due to hyperparathyroidism and malignancy. Other causes include disorders leading to vitamin D elevation, granulomatous diseases, and the use of certain pharmacological agents. Calcium levels are regulated and affected by factors such as dietary intake and pH, and the levels of parathyroid hormone (PTH), vitamin D, and albumin. Symptoms vary depending on calcium levels and the onset of hypercalcemia. Generally, neuropsychiatric (confusion, altered mental status), GI (vomiting, abdominal pain), musculoskeletal (bone pain, weakness), and renal (polyuria, polydipsia) manifestations are seen. Confirmation of hypercalcemia is required. Correction of the value is based on the albumin levels or after determining the ionized calcium levels (the metabolically active form), which is followed by determining PTH levels. Subsequent laboratory tests and imaging studies are ordered based on history and presentation. Correction of hypercalcemia depends on its severity. Calcium levels > 14 mg/dL are treated using IV isotonic saline hydration, calcitonin, and bisphosphonates. Hemodialysis is considered in rare cases. Treatment of the underlying cause is recommended.
An abdominal hernia is an abnormal protrusion of the abdominal contents through a weakness or defect of the abdominal wall, and can be congenital or acquired. There are multiple types of hernias based on the anatomic location and the underlying pathophysiology. The most common hernias encountered in surgical practice include ventral, inguinal, and femoral hernias. Hernias are most commonly diagnosed on physical exam (abnormal bulge or protrusion), but imaging studies can sometimes be helpful for a definitive diagnosis. The management consists of surgical repair. The decision for surgery is based on patients’ symptoms, their desire for surgical repair, and risks of incarceration and strangulation. Surgical options include open and laparoscopic approaches, with or without the placement of a prosthetic mesh.
The pancreas is a composite organ containing a distinctive combination of cell lineages. The exocrine tissue comprises acinar cells, which secrete digestive enzymes into the intestine. The endocrine function is performed by the islets of Langerhans, which consist of distinct cell types secreting 4 different hormones into the circulation (α-cells, glucagon; β-cells, insulin; δ-cells, somatostatin; and γ-cells, pancreatic polypeptide). Endocrine hormones, as well as some exocrine enzymes, can be measured in body fluids and provide important diagnostic information in acute and chronic pancreatic disease.
Statins are competitive inhibitors of HMG-CoA reductase in the liver. HMG-CoA reductase is the rate-limiting step in cholesterol synthesis. Inhibition results in lowered intrahepatocytic cholesterol formation, resulting in up-regulation of LDL receptors and, ultimately, lowering levels of serum LDL and triglycerides. Statins can lower LDL 20%–60% (depending on their intensity) and have benefits that are cholesterol-independent (e.g., reduced vascular inflammation and atherosclerotic plaque stabilization). Indications for prescribing statins include prevention of primary or secondary cardiovascular disease in patients with dyslipidemia. The main adverse effects are transaminitis and muscle toxicity.
The term "disorders of sexual development" refers to a group of conditions characterized by atypical sexual development in an individual, which may involve abnormalities in the structure and/or function of the internal reproductive organs and/or external genitalia. Typical sex development starts with the chromosomal sex (e.g., 46,XY or 46,XX), which determines the sexual differentiation of the gonads (e.g., testes or ovaries), which secrete hormones that determine the phenotype (e.g., male or female). Most disorders of sexual development are due to abnormalities in specific chromosomes, enzymes, or receptors. Diagnosis typically involves analyzing the karyotype and specific hormone levels. Management can be complex, and often includes psychotherapy, hormone replacement therapy, and/or surgery.
The vertebral column is the most important anatomical and functional axis of the body, consisting of 7 cervical, 12 thoracic, and 5 lumbar vertebrae and limited cranially by the skull and caudally by the sacrum. The vertebral column provides structural support and protection for the spinal cord, which is housed in the spinal canal. The vertebral column and the spinal cord may be affected by various diseases, in which different imaging methods are important for correct diagnosis and management. Radiographs and CT scans are useful in evaluating bony structures, especially in excluding fractures and checking hardware. Additionally, CT scans also provide information on soft tissues. MRI is performed for evaluation of tumors, infection, disk herniations, and other soft tissue abnormalities including acute ligamentous or spinal cord injury.
Postpartum hemorrhage is one of the most common and deadly obstetric complications. Since 2017, postpartum hemorrhage has been defined as blood loss greater than 1,000 mL for both cesarean and vaginal deliveries, or excessive blood loss with signs of hemodynamic instability. Blood loss of more than 500 mL following a vaginal delivery is considered abnormal, though no longer classified as postpartum hemorrhage. The most common cause of postpartum hemorrhage is uterine atony. Retained products of conception, trauma, and coagulopathies may also cause postpartum hemorrhage. Appropriate management requires rapid identification of the cause of the hemorrhage, medical and/or surgical correction, and patient resuscitation.
Chronic kidney disease (CKD) is kidney impairment that lasts for ≥ 3 months, implying that it is irreversible. Hypertension and diabetes are the most common causes; however, there are a multitude of other etiologies. In the early to moderate stages, CKD is usually asymptomatic and is primarily diagnosed by laboratory abnormalities. Regardless of the etiology, progression of renal impairment is common and can ultimately lead to end-stage renal disease and the need for renal replacement therapy (e.g., transplantation or dialysis). The management of CKD includes treating the underlying etiology, aggressive risk factor modification, and addressing complications such as fluid overload and electrolyte imbalances.
Bartter syndrome is a rare autosomal recessive disorder that affects the kidneys and presents either antenatally with severe or life-threatening manifestations or in childhood or adulthood with a milder course, depending on the genetic defect. Clinical disease results from defective renal reabsorption of sodium chloride in the thick ascending limb of the loop of Henle, where 30% of filtered salt is normally reabsorbed. Bartter syndrome is characterized by salt wasting and hypokalemia and presents with electrolyte abnormalities and their consequences, such as vomiting and dehydration. Diagnosis is made by lab testing that shows the typical hypokalemic metabolic alkalosis and hypercalciuria. Additional lab abnormalities include increased serum renin and aldosterone, but patients clinically have normal blood pressure. Management is focused on normalizing serum electrolyte levels. ACE inhibitors and angiotensin receptor blockers are used to improve hypokalemia and limit proteinuria.
Adenovirus (member of the family Adenoviridae) is a nonenveloped, double-stranded DNA virus. Adenovirus is transmitted in a variety of ways, and it can have various presentations based on the site of entry. Presentation can include febrile pharyngitis, conjunctivitis, acute respiratory disease, atypical pneumonia, and gastroenteritis. Severe manifestations include acute hemorrhagic cystitis, hepatitis, myocarditis, and disseminated infection. The diagnosis is confirmed with PCR and antigen testing. Most infections are self-limited, so management is generally supportive. Antiviral therapy is reserved for immunocompromised patients and severe infections.
Ependymomas are glial cell tumors arising from CSF-producing ependymal cells lining the ventricular system. Ependymomas most commonly occur within the posterior fossa in contact with the 4th ventricle, or within the intramedullary spinal cord. The clinical presentation of ependymomas varies depending on the location of the tumor. Magnetic resonance imaging is the imaging modality of choice, but histologic confirmation is required for diagnosis. The mainstay of treatment for intracranial ependymoma is surgical resection and adjuvant radiation therapy; young patients receive chemotherapy instead. Spinal cord ependymomas are treated with maximal surgical resection.
Norovirus is a nonenveloped, single-stranded, positive-sense RNA virus belonging to the Caliciviridae family. Norovirus infections are transmitted via the fecal-oral route or by aerosols from vomiting. The virus is one of the most common causes of non-bacterial gastroenteritis epidemic worldwide. Symptoms include watery and nonbloody diarrhea, nausea, vomiting, and low-grade fever. Although the infection is self-limiting, severe dehydration can occur. The diagnosis is usually presumptive, and viral detection using PCR or enzyme immunoassay may be used for patients with severe disease or immunocompromised status. Management is supportive and may include rehydration therapy.
Metabolic syndrome is a cluster of conditions that significantly increases the risk for several secondary diseases, notably cardiovascular disease, type 2 diabetes, and nonalcoholic fatty liver. In general, it is agreed that hypertension, insulin resistance/hyperglycemia, and hyperlipidemia, along with central obesity, are components of the metabolic syndrome. The diagnosis includes measurements of the waist circumference and BP along with serum levels of triglycerides, HDL cholesterol, and fasting glucose. Management consists mostly of lifestyle modifications such as moderate exercise and a balanced diet high in fibers and unsaturated fats and low in sugar.
Medulloblastomas are malignant primitive neuroectodermal tumors that arise in the posterior fossa in children. Medulloblastomas are the most common malignant brain tumors in children. Patients with medulloblastoma present with symptoms of increased intracranial pressure and cerebellar signs, which both evolve and worsen over weeks to a few months. Magnetic resonance imaging is the imaging modality of choice and typically shows a midline or paramedian cerebellar mass that enhances with contrast, but histopathological analysis after surgical resection is required for diagnosis. Treatment involves a combination of surgery, radiation therapy, and chemotherapy. Prognosis depends on a variety of factors, but with modern multimodality therapy, roughly 75% of children diagnosed with medulloblastoma survive into adulthood.
Glioblastoma multiforme is a high-grade astrocytoma, an aggressive brain tumor arising from astrocytes, with an unknown cause and a poorly understood link to risk factors. There are two main types: primary, a more aggressive form seen more commonly in older patients, and secondary, developing from lower-grade astrocytomas and seen more commonly in younger patients. Glioblastomas most commonly present with headache, seizures, and neurologic deficits. MRI is the gold standard diagnostic tool, and surgical resection combined with radiation and chemotherapy is the treatment of choice. Prognosis is extremely poor, with survival of only 1–5 years in patients receiving aggressive treatment and only 3 months in patients who do not undergo treatment.
Heavy metals poisoning is the toxic accumulation of metals in the body, which can occur due to ingestion or inhalation. These elements are normally found in nature and can have many applications (e.g., agriculture, medicine, industry); however, toxicity is rare. Common metals that the human body absorbs in toxic amounts are lead, arsenic, and iron. Presentation is variable and management involves the use of chelating agents.
Neuroleptic malignant syndrome (NMS) is a rare, idiosyncratic, and potentially life-threatening reaction to antipsychotic drugs. Neuroleptic malignant syndrome presents with ≥ 2 of the following cardinal symptoms: fever, altered mental status, muscle rigidity, and autonomic dysfunction. It is important to promptly identify this condition because of its high morbidity and mortality rates. Diagnosis is based on positive clinical and laboratory findings, along with the exclusion of other possible causes. Management involves discontinuing antipsychotic medication, supportive care, and pharmacologic options.
Rotavirus belongs to the Reoviridae family and is a non-enveloped, double-stranded RNA virus. Transmission occurs through the fecal-oral route. Rotavirus is a common cause of severe gastroenteritis in children. Severe infections can result in dehydration and death. Diagnostic testing is not usually required, but the virus can be detected in stool samples using ELISA or PCR. Oral rehydration therapy is the mainstay of treatment. A live-attenuated vaccine is available to prevent rotavirus infections.
The kidneys regulate water and solute homeostasis through the processes of filtration, reabsorption, secretion, and excretion. After the filtration of blood through the glomeruli, the tubular system takes over and is responsible for adjusting the urine composition throughout the remainder of the nephron. Reabsorption, secretion, and excretion occur via active and passive transport mechanisms and respond dynamically to the body’s current needs to maintain homeostasis of the plasma composition and blood volume. The primary segments of the tubular system include the proximal tubule, loop of Henle, distal convoluted tubule, and collecting ducts. Each segment has unique transporters and functions.
Tobacco use is the leading cause of preventable death in the world. Tobacco use is directly related to a higher risk of chronic obstructive pulmonary disease (COPD), cardiovascular diseases, and various cancers. Nicotine, the psychoactive component of tobacco, stimulates nicotinic receptors in the autonomic ganglia of the sympathetic and parasympathetic nervous systems. Nicotine is highly addictive through its effects on the dopaminergic system. Treatment includes medications to prevent cravings, nicotine-replacement therapy, and psychotherapy.
Post-streptococcal glomerulonephritis (PSGN) is a type of nephritis that is caused by a prior infection with group A beta-hemolytic Streptococcus (GAS). The clinical presentation of PSGN can range from asymptomatic, microscopic hematuria to full-blown acute nephritic syndrome, which is characterized by red-to-brown urine, proteinuria, edema, and acute kidney injury. The diagnosis is made based on clinical findings in the setting of recent GAS infection. Management is supportive and involves treating the clinical manifestations. The prognosis is generally favorable, especially in children.
Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of
A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Clinical presentation varies depending on the cause and location of the injury, but generally includes deformity, pain, edema, and inflammation. Diagnosis is made clinically and confirmed with imaging, and management may be with splinting or may require surgery.
Imaging of the brain is most commonly used for evaluating trauma, stroke, and benign or malignant tumors. Before the advent of CT and MRI, X-ray scanning was widely used to study the skull and spinal bones. Today, CT and MRI, especially the latter, are the preferred imaging methods for the study of the cranial vault and its contents. In conditions where emergent management is decided on the basis of presentation and imaging, CT has the advantage of rapid scan time and wider availability. CT also has good sensitivity and specificity and relatively lower cost. MRI though, provides better parenchymal characterization especially in cases where initial findings are negative on CT (such as in acute ischemia).
Human papillomavirus (HPV) is a nonenveloped, circular, double-stranded DNA virus belonging to the Papillomaviridae family. Humans are the only reservoir, and transmission occurs through close skin-to-skin or sexual contact. Human papillomaviruses infect basal epithelial cells and can affect cell-regulatory proteins to result in cell proliferation. There are > 200 serotypes that can cause several conditions, including cutaneous warts, anogenital warts, and neoplasms.
Neuroblastoma is a malignancy that arises from the neural crest cell derivatives along the sympathetic chain (neuroblasts) and is most commonly located in the adrenal medulla. The tumor often presents in childhood with a flank mass that crosses the midline. Neuroblastoma can also manifest as opsoclonus-myoclonus paraneoplastic syndrome. The tumor is diagnosed through biopsy, and supporting data include measuring the catecholamine breakdown products such as vanilmandelic acid (VMA) and homovanillic acid (HVA) in urine. Imaging studies are needed to localize the tumor. Management depends on several factors such as the stage of malignancy and the patient’s age at the time of diagnosis. Prognosis is favorable in the early stages of neuroblastoma.
Elbow dislocation is the displacement of either the radius or the ulna relative to the humerus. The most common mechanism of injury is falling on an outstretched hand. Elbow dislocation presents with joint swelling, pain, and restricted range of motion. Dislocation of the elbow can be classified into simple or complex depending on the absence or presence, respectively, of a concomitant fracture. Dislocations are diagnosed with an X-ray. Management depends on whether the dislocation is simple or complex. Simple dislocations are managed with joint immobilization and casting, while complex dislocations require open reduction and internal fixation. Elbow dislocations can be complicated by joint contractures, which are due to fibrotic changes in the joint capsule, or permanent joint instability, which are due to loose ligaments.
An orbital fracture is a break in the continuity of one or multiple bones of the eye socket, caused by direct or indirect trauma to the orbit. Patients frequently present with lacerations around the eye, orbital pain, edema, ecchymosis, diplopia on upward gaze, numbness around the eye, and signs of muscle entrapment. Diagnosis is based on clinical exam and imaging. The mainstay of management is to prevent further injury to the eye while determining whether surgery is needed. Complications include orbital compartment syndrome, blindness, and persistent diplopia.
Neutropenic fever is a medical emergency defined as a fever > 38.3℃ (100.9℉) or higher than 38.0℃ (100.4℉) for more than 1 hour in neutropenic patients. Neutropenic fever is a common life-threatening complication of hematologic malignancies and in patients undergoing chemotherapy. Patients are often asymptomatic, and the only sign is the presence of fever. Diagnosis should include a detailed history, physical examination, and routine laboratory tests, in addition to symptom-directed workup with cultures. Initial management includes the administration of empiric antibiotics adjusted according to clinical response and culture results.
After any procedure performed in the operating room, all patients must undergo close observation at least in the recovery room. After larger procedures and for patients who require hospitalization, observation must continue on the surgical ward. The primary intent of this practice is the early detection of postoperative complications. The entire medical team must be vigilant and aware of the patient’s history, the procedure performed, and risk factors for potential complications. Some of the most important things to attend to include monitoring vital signs (which may indicate severe complications such as bleeding), wound and drain care, postoperative pain control, nausea and vomiting, pulmonary hygiene to prevent atelectasis, deep vein thrombosis prophylaxis, and fluid management.
Acromegaly and gigantism are caused by an excessive production of growth hormone (GH) by the pituitary gland. Tall stature is a clinical sign observed in some patients with gigantism. Increased GH and insulin-like growth factor-1 (IGF-1) are responsible for inducing hypersomatotropism. Acromegaly is usually produced by pituitary tumors secreting GH or, less commonly, by extrapituitary disorders. Gigantism typically results in children from excess GH before growth-plate closure; acromegaly typically results from excess GH after growth-plate closure. Diagnosis involves neuroimaging of the pituitary and laboratory tests to evaluate the hypothalamic-pituitary axis. Treatment depends on the operative status of the tumor (if present), or a nonoperative treatment strategy may be utilized.
The knee joint is made up of the articulations between the femur, tibia, and patella bones, and is one of the largest and most complex joints of the human body. The knee is classified as a synovial hinge joint, which primarily allows for flexion and extension with a more limited degree of translation and rotation. The supporting structures of the knee joint include a joint capsule, the lateral and medial menisci, and multiple ligaments that help ensure mobility and stability of the knee.
An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Electrocardiograms are simple, inexpensive, noninvasive, and readily obtained. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. In the healthy state, an ECG records predictable, reproducible waves and complexes, which correspond to electromechanically coupled physiologic events in the heart. Under pathologic conditions, the ECG can detect arrhythmias, ischemia, inflammation, and more.
A hip fracture is a disruption in the cortex of the femur at the hip joint, either between the trochanters (intertrochanteric) or at the femoral neck. Hip fracture is a serious injury and can result in life-threatening complications. The causes include high-energy impact due to trauma such as in motor vehicle accidents, or low-energy trauma (falls) in patients with osteoporosis. The clinical presentation includes groin pain, tenderness on palpation, immobility, and deformity of the lower limbs. Diagnosis is made clinically and by imaging studies. Definitive management is usually surgical, but depends on the type of fracture and status of the patient.
Laxatives are medications used to promote defecation. Most often, laxatives are used to treat constipation or for bowel preparation for certain procedures. There are 4 main classes of laxatives: bulk-forming, stimulant, osmotic, and emollient. Often, a combination of these medications is required to have the desired effect. All laxatives can result in bloating. Laxative overuse can induce diarrhea and dehydration. Non–anion gap metabolic acidosis occurs owing to bicarbonate loss in the feces, while metabolic alkalosis occurs because of volume contraction.
The end of a patient’s life has been a difficult, complex, and often controversial aspect of medicine, because, historically, death has been conceptualized as a “failure” on the physician’s part. As our understanding of death has evolved, so has the physician's relationship to it, becoming a companion to the patient in their final moments. Moreover, experienced doctors understand that during the last days of a person’s life, the focus must be on maximizing quality of life rather than on prolonging it.
An infection is the proliferation of microorganisms within tissues, body cavities, or spaces, which induces an immune response and overwhelms the body’s natural defenses. In surgical patients, these infections are frequently caused by the translocation of commensal organisms into deeper tissues, combined with the impairment of host defenses due to surgical injury or stress. Infections commonly identified in patients after surgery include surgical site infections, catheter-associated infections, and ventilator-associated infections. Infection subtypes can be prevented, diagnosed, or treated using several strategies. The mainstays of treatment in surgical patients involve local control of the infection as well as targeted antibiotic therapy.
Stable and unstable angina are considered an important symptom of coronary heart disease (CHD) and present with chest pain due to transient myocardial ischemia. These disorders can be a warning sign for the risk of heart attack (MI) in the future. Clinically, stable and unstable angina are differentiated by exacerbating factors, duration of symptoms, and response to rest and medications. Diagnosis is by history and examination, ECG, stress testing with possible additional nuclear medicine imaging, echocardiography, or coronary angiography. Management with lifestyle modifications and aggressive risk factor reduction (of hypertension, diabetes, and hyperlipidemia) is indicated to prevent the risk of progression to MI and death.
MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Diagnosis is by clinical history, ECG changes, an increase in cardiac enzymes, and evidence of wall motion abnormalities on imaging. Management depends on the timing of the presentation and local resources with regard to thrombolytic therapy versus percutaneous intervention. All patients receive nitrates, pain control, aspirin, anticoagulation, and beta-blockers (unless contraindicated).
Malabsorption involves many disorders in which there is an inability of the gut to absorb nutrients from dietary intake, potentially including water and/or electrolytes. A closely related term, maldigestion is the inability to break down large molecules of food into their smaller constituents. Malabsorption and maldigestion can affect macronutrients (fats, proteins, and carbohydrates), micronutrients (vitamins and minerals), or both. These disorders present with weight loss, diarrhea, weakness, and fatigue. There are many causes, and the goal of management is to reduce symptoms, with specific treatments aimed at the underlying cause.
Testicular cancer is the most common solid malignancy affecting men 15–35 years of age. Most of the testicular cancers are of the germ cell tumor type, and they can be classified as seminomas and nonseminomas. The most common presentation of testicular cancer is a painless testicular mass. Diagnosis is via physical exam, testicular ultrasonography, and serum tumor markers. Additional imaging helps with staging and assessment of metastasis. Treatment consists of surgical inguinal orchiectomy, and further adjuvant therapy is based on disease pathology and stage. Subsequent strategies include disease surveillance, radiotherapy, and chemotherapy. Disease prognosis is excellent, as testicular cancer is one of the most curable solid neoplasms.
Sexual abuse and assault are major public health problems that affect many people from all walks of life, including people of all ages and genders, but it is more prevalent in women and girls, with reports of up to 1 in 3 experiencing sexual assault at some time in their life. In addition to psychological consequences, sexual assault can result in unintended pregnancy, STIs, and physical injury. Management includes proper examination, testing, reporting, and psychological support.
Hypoglycemia is an emergency condition defined as a serum glucose level ≤ 70 mg/dL (≤ 3.9 mmol/L) in diabetic patients. In nondiabetic patients, there is no specific or defined limit for normal serum glucose levels, and hypoglycemia is defined mainly by its clinical features. Hypoglycemia is most commonly seen in diabetic patients as a result of inadequate oral intake with insulin administration, but it can also be seen in hypermetabolic states, such as sepsis, or malnutrition states, such as chronic alcohol use or prolonged fasting. Hyopoglycemia may present with a variety of nonspecific symptoms, including adrenergic symptoms (sweating, tachycardia, tremulousness) and neuroglycopenic symptoms (dizziness, confusion, lethargy, loss of consciousness). Diagnosis is based on serum glucose measurement and clinical presentation. Management depends on the severity of symptoms. A patient with normal mental status may be able to take oral glucose gel or sugary drinks, but a patient with altered mental status will need IV dextrose and frequent serum glucose checks.
Gitelman syndrome is a rare genetic autosomal recessive disorder that affects the sodium–chloride cotransporter in the distal convoluted tubule of the nephron and causes electrolyte abnormalities. The syndrome presents clinically with symptoms of hypokalemia and hypomagnesemia. Diagnosis is based on the clinical presentation of the syndrome with lab testing as well as genetic testing for family counseling. The mainstay of management is potassium and magnesium supplementation to prevent development of symptoms. The prognosis is good, but hypokalemia must be monitored to prevent cardiac arrhythmias and potential cardiac arrest.
Herpes simplex virus (HSV) is a double-stranded DNA virus belonging to the family Herpesviridae. Herpes simplex virus commonly causes recurrent infections involving the skin and mucosal surfaces, including the mouth, lips, eyes, and genitals. Typical mucocutaneous infections are characterized by an acute localized appearance of clusters of small, painful vesicles on an erythematous base. Although overlap exists, HSV-1 is classically associated with oropharyngeal lesions, whereas HSV-2 is mostly responsible for genital herpes, an STI. Systemic and severe infections including encephalitis, meningitis, and neonatal herpes may also occur. The diagnosis is made based on clinical presentation and history, which can be confirmed by the microscopic examination of a stained smear of a fresh vesicle, nucleic amplification test using PCR, direct immunofluorescence, or serologic tests. The therapy for mucocutaneous lesions is usually symptomatic, but antiviral therapies involving acyclovir, valacyclovir, or famciclovir are useful if given early, and are always part of the therapy for serious systemic infections.
Familial adenomatous polyposis (FAP) is an autosomal dominant inherited genetic disorder that presents with numerous adenomatous polyps in the colon. Familial adenomatous polyposis is the most common of the polyposis syndromes, which is a group of inherited or acquired conditions characterized by the growth of polyps in the GI tract, associated with other extracolonic features. These syndromes are caused by mutations in specific genes associated with tumor suppression or cell cycle regulation. All patients with FAP will develop colon cancer by age 35–40 years if left untreated. Management is with a surveillance program and colectomy.
Peutz-Jeghers syndrome (PJS) is an autosomal-dominant inherited disorder characterized by GI polyps and mucocutaneous-pigmented macules. Peutz-Jeghers syndrome is 1 of the polyposis syndromes, a group of inherited or acquired conditions characterized by the growth of polyps in the GI tract and associated with other extracolonic features. The syndromes are caused by mutations in specific genes associated with tumor-suppression or cell-cycle regulation. Peutz-Jeghers syndrome is caused by disruptions in the STK11 gene and is associated with colonic (colorectal) and noncolonic (pancreatic, gastric, breast, uterine, cervical, lung, ovarian, and testicular) cancers. Management is with close surveillance and surgery.
Acute lymphoblastic leukemia/lymphoma (ALL/LBL) are hematologic malignancies characterized by the uncontrolled proliferation of lymphoid precursor cells. Acute lymphoblastic leukemia/lymphoma, the most common forms of cancer affecting children, show the presence of increased lymphoblasts. In ALL/LBL, lymphoblasts replace the normal marrow, eventually entering the circulation and infiltrating other organs. The clinical presentation includes fatigue, bleeding, fever, and infections, all of which are related to anemia, thrombocytopenia, and the lack of functional WBCs. The onset of symptoms takes days to weeks. Mass effects of malignant infiltration (in bone, liver, spleen) are common; thus, hepatosplenomegaly and lymphadenopathy are seen. Diagnosis is by peripheral blood smear examination and bone marrow biopsy, which show the presence of lymphoblasts. Immunophenotyping, histochemistry, and genetic studies aid in the classification and guidance of treatment. Management is mainly by chemotherapy, which is administered in phases (induction, consolidation, and maintenance). Prognosis varies according to the age of onset and type of leukemia. The cure rate in children is 85%.
Surgical site infection (SSI) is a type of surgical infection that occurs at or near a surgical incision within 30 days of the procedure or within 90 days if prosthetic material is implanted. Surgical site infections are classified according to the depth of involvement as superficial, deep, or organ/space. Diagnosis relies on clinical findings and may require diagnostic imaging. Management involves antibiotics as well as surgical drainage/debridement as necessary.
Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. The disorder can usually be managed with lifestyle modification and medications, but occasionally, vascular intervention or surgery are required. Age, sex, smoking, obesity, and diet are contributing factors to hypertension, which can lead to heart attack, stroke, congestive heart failure, and CKD if not managed properly. Many individuals with hypertension are undiagnosed or undertreated.
Thiazide and thiazide-like diuretics make up a group of highly important antihypertensive agents, with some drugs being 1st-line agents. The class includes hydrochlorothiazide, chlorothiazide, chlorthalidone, indapamide, and metolazone. These drugs block sodium reabsorption in the distal convoluted tubule of the kidney by inhibiting the sodium-chloride cotransporter. As a result, the increased sodium excretion causes secondary water excretion because water follows the sodium. In addition to increasing sodium and water excretion, thiazide diuretics also cause the excretion of chloride, potassium, magnesium, and protons (H+).
The carotid arterial system provides blood supply to the head and neck. The arterial system begins as the common carotid artery, which arises directly from the aortic arch on the left side and from the brachiocephalic trunk/artery on the right. The common carotid arteries then ascend through the neck and divide into the internal and external carotid arteries. The former supplies structures within the brain and orbits, whereas the latter supplies the superficial structures and parts of the neck and face.
Hypogonadism is a condition characterized by reduced or no sex hormone production by the testes or ovaries. Hypogonadism can result from primary (hypergonadotropic) or secondary (hypogonadotropic) failure. Hypergonadotropic hypogonadism results when the gonads fail, and hypogonadotropic hypogonadism results from failures in the hypothalamic–pituitary–gonadal axis. Symptoms include infertility, increased risk of osteoporosis, erectile dysfunction, decreased libido, and regression (or absence) of secondary sexual characteristics. Diagnosis is guided by the history, physical exam, measurement of hormone levels, and an evaluation for an underlying etiology. Management is with hormone replacement.
A toxidrome is a group of clinical signs and symptoms associated with a toxic ingestion or exposure. There are 5 traditional toxidromes: anticholinergic, cholinergic, opioid, sympathomimetic, and sedative-hypnotic. Toxidromes often arise from ingestion of overdose amounts, accumulation of medications with resultant elevated serum levels, adverse drug reactions, or interactions between 2 or more medications. Rapid recognition of a toxidrome can help determine the specific poison or class of toxin that was ingested. On presentation of a suspected toxidrome, appropriate airway, breathing, and circulation assessment is initiated. Decontamination is performed, and the patient is stabilized. Diagnosis is accomplished with clinical findings based on medication and exposure history, vital signs, mental status, and physical examination. Testing generally includes toxicology and drug levels, electrolytes, and ECG. Management consists of supportive care and antidote administration if indicated.
Osmotic diuretics increase tubular fluid osmolarity, pulling water into the collecting tubules and preventing water reabsorption, which results in osmotic diuresis. The primary osmotic diuretic used clinically is mannitol. The primary indication for mannitol is to treat cases of increased intracranial or intraocular pressure, which can have significant effects on fluid volume and sodium concentration, so caution must be exercised when using these agents.
Carbonic anhydrase inhibitors (CAIs) block the carbonic anhydrase enzymes in the proximal convoluted tubule, inhibiting the reabsorption of sodium bicarbonate (NaHCO3), which results in diuresis and metabolic acidosis. Carbonic anhydrase inhibitors also block the carbonic anhydrase present in the eyes and glial cells, resulting in decreased aqueous humor and CSF production, respectively. Acetazolamide is the prototypical CAI. Carbonic anhydrase inhibitors are mainly used for the treatment of altitude sickness, edema in patients with metabolic alkalosis, glaucoma, and, sometimes, as an adjuvant treatment for certain types of epilepsies and increased intracranial pressure. Carbonic anhydrase inhibitors are not used for the treatment of hypertension.
Disease-modifying antirheumatic drugs are antiinflammatory medications used to manage rheumatoid arthritis. The medications slow, but do not cure, the progression of the disease. The medications are classified as either synthetic or biologic agents and each has unique mechanisms of action and side effects. Common side effects among the disease-modifying antirheumatic drugs include bone marrow suppression and hepatotoxicity. Leflunomide, methotrexate, and tumor necrosis factor (TNF)-ɑ inhibitors are avoided in pregnancy due to their potential teratogenicity. Hydroxychloroquine and sulfasalazine are safe for use during pregnancy.
Opiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates. Known for their remarkable efficacy, opioids induce their effects (analgesia, euphoria, and sedation) by interacting with opioid receptors (μ, κ, and δ) in the nervous system. Opiates/opioids have adverse effects that include respiratory depression, nausea and vomiting, decreased GI motility and constipation, tolerance, dependence, and addiction.
Radial head subluxation, also known as nursemaid’s elbow or babysitter’s elbow, is a frequent injury seen in children under 4 years of age and describes the subluxation of the radial head under the annular ligament at the elbow. The injury primarily occurs when a child is pulled, swung, or lifted by 1 arm. Patients present holding their injured upper limb in a guarded and pronated position. Diagnosis is made clinically and the condition is managed by a closed-reduction maneuver. Prognosis is excellent when diagnosed in a timely manner.
Antepartum hemorrhage is defined as vaginal bleeding that occurs after 20 weeks of gestation and is unrelated to labor. The most important causes are placental abruption (most common), placenta previa (2nd most common), vasa previa, and uterine rupture. Placental abruption and uterine rupture are diagnosed clinically. Placenta previa and vasa previa are usually diagnosed as part of routine screening on a midtrimester ultrasound, and digital exams in these women must be avoided. All of these conditions can lead to maternal and/or fetal hemorrhage, necessitating emergency C-section and maternal and/or fetal resuscitation.
Male sexual dysfunction is any disorder that interferes with the male sexual response cycle and includes desire disorders, erectile disorders, and ejaculatory disorders. Sexual dysfunction has a varied etiology and may be due to psychological causes, endocrine diseases, neurogenic dysfunction, chronic medical illness, or medication/substance abuse. These disorders often cause significant distress to the patient and sexual partner. Treatment options include psychotherapy, physical therapy, and pharmacotherapy based on the causes of dysfunction.
Diarrhea is described as passage of large amounts stools that are often loose, liquid, or watery, resulting in excess loss of fluids and electrolytes. Diarrhea is one of the most common illnesses in children, representing the largest percentages of morbidity and mortality worldwide in the pediatric age group. The majority of cases are infectious, caused by rotavirus, while the rest are caused by bacteria (Escherichia coli, Salmonella) and parasites (Entamoeba histolytica). Management is largely based on rehydration; antibiotic therapy is used only when indicated. Prognosis is excellent if diarrhea promptly treated.
Prenatal care is a systematic and periodic assessment of pregnant women during gestation to assure the best health outcome for the mother and her fetus. Prenatal care prevents and identifies maternal and fetal problems that adversely affect the pregnancy outcome. Prenatal visits involve scheduled screening tests such as prenatal ultrasounds or blood glucose tests and measurements of fetal/maternal health metrics. These visits are also opportunities to educate pregnant women about pregnancy, labor, delivery, and parenting while providing psychological support to patients and their families.
Herbicides are chemical substances used to kill or control the growth of unwanted plants. Important herbicides that can affect humans include paraquat, Agent Orange, glyphosate, and organophosphates. Different types of herbicides result in different clinical manifestations and have various toxicity levels. Paraquat ingestion is associated with multiorgan damage within a few hours and is fatal in large amounts. In contrast, glyphosate typically has low toxicity, but if a significant volume is ingested, serious adverse effects occur. Organophosphates, which are broadly used as pesticides, produce a cholinergic toxidrome. Agent Orange, containing 2,3,7,8-tetrachlorodibenzo-p-dioxin, a human carcinogen, carries both short-term (e.g., chloracne, liver toxicity) and long-term (e.g., cancers) complications. Exposure can be dermal or via inhalation or ingestion. In general, early detection is important to prevent serious sequelae. Initial management consists of stabilizing the patient and decontamination. An antidote is given, if available. Treatment of herbicide poisoning revolves around supportive care that depends on the involved organ system.
Loop diuretics are a group of diuretic medications primarily used to treat fluid overload in edematous conditions such as heart failure and cirrhosis. Loop diuretics also treat hypertension, but not as a 1st-line agent. The medication inhibits sodium reabsorption through the NKCC2 cotransporter in the thick ascending limb of the loop of Henle (TAL), leading to significant diuresis. Careful monitoring is important because loop diuretics result in increased excretion of sodium, potassium, chloride, calcium, magnesium, and water. In addition to electrolyte and fluid abnormalities, loop diuretics can lead to nephrotoxicity and ototoxicity.
Potassium-sparing diuretics are medications that act in the principal cells in the collecting ducts to induce diuresis that does not result in excretion of potassium. These diuretics include 2 subclasses: sodium channel blockers and aldosterone antagonists. Because these agents act so distally in the nephron, there is no significant potassium wasting associated with their use. These agents are typically used in the treatment of mineralocorticoid excess, which may be either primary (e.g., Conn syndrome) or secondary (e.g., states of depleted intravascular volume, especially in heart failure patients). Additionally, spironolactone can be used for its antiandrogenic properties in women with androgen excess (e.g., hirsutism) and for androgen suppression in transgender women (male-to-female). These drugs are contraindicated in cases of hyperkalemia.
Familial juvenile polyposis, also known as juvenile polyposis syndrome, is an autosomal dominant condition characterized by the growth of hyperplastic, hamartomatous polyps in the colon. Polyposis syndromes are a group of inherited or acquired conditions characterized by the growth of polyps in the GI tract, and are associated with other extracolonic features. These syndromes are caused by mutations in specific genes associated with tumor suppression or cell cycle regulation. Familial juvenile polyposis is commonly associated with mutations in the SMAD4 (chromosome 18q) and BMPR1A (chromosome 10q) genes. Diagnosis is made by visualizing 5 or more polyps on colonoscopy, or any number plus a positive family history. Management is surgical in order to reduce the likelihood of GI bleeding and obstruction.
Although hepatocellular carcinoma (HCC) is by far the most common malignant liver tumor, there are several rare malignant tumors that are important to keep in mind when making a differential diagnosis. These tumors include cholangiocarcinoma; hepatoblastoma and mesenchymal tumors, such as epithelioid hemangioendothelioma (EHE); and angiosarcoma. While these conditions differ in their etiology and pathology, they often present similarly, with nonspecific symptoms such as fatigue, weight loss, and abdominal discomfort. Diagnosis is by imaging, which can be supported by a biopsy. Surgical excision is the only curative approach for these tumors.
An antidote is a substance that counteracts poisoning or toxicity. Substances that can cause poisoning include heavy metals (from occupation, treatments, or diet), alcohols, environmental toxins, and medications. An increase in the concentration of these substances to toxic levels can occur accidentally or intentionally, resulting in both acute and chronic presentations. Some substances can be detected using specific laboratory tests, whereas the detection of others relies on nonspecific findings. Thus, it is important to recognize substance poisoning by history, individual risk factors, and physical examination. Antidotes along with supportive care and monitoring are part of the management.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder marked by poor social skills, restricted interests/social interactions, and repetitive/stereotyped behaviors. The condition is termed a “spectrum” because of the wide variability in the severity of symptoms exhibited. Some patients suffer from severe impairment in language and intellectual levels, while others have normal or even advanced intellect. The etiology is not well understood and there is no known cure. Early diagnosis and intervention are important in improving the patient’s symptoms.
Hepatocellular carcinoma (HCC) typically arises in a chronically diseased or cirrhotic liver and is the most common primary liver cancer. Diagnosis may include ultrasound, CT, MRI, biopsy (if inconclusive imaging), and/or biomarkers. Treatment options include resection and chemo-/radiotherapy, and liver transplantation in select cases. Liver metastases are much more common than primary liver cancers and usually originate from colorectal, lung, breast, and pancreatic primary sites. Metastases are most commonly diagnosed by CT or PET scans. Management depends on the type and stage of primary cancer.
Antiprogestins are competitive inhibitors of progestins at the progesterone receptors. Mifepristone, lilopristone, and onapristone are the 3 antiprogestins that are currently used. The most common clinical use of mifepristone is for the termination of pregnancy. Mifepristone is often combined with a prostaglandin such as misoprostol. Selective receptor progesterone modulators (SPRMs) are closely related drugs with a slightly different mechanism of action, and act as either agonists or antagonists depending on the cellular environment. Examples of SPRMs include ulipristal, asoprisnil, and telapristone. Ulipristal is used as an emergency contraceptive; its mechanism of action is by the inhibition of luteinizing hormone and delaying ovulation. The common side effects of antiprogestins and SPRMs include nausea, vomiting, and abdominal pain.
The postpartum period is typically defined as the first 6–12 weeks following delivery of an infant. During this time, postpartum complications can occur either as a result of the normal physiologic changes the body undergoes to return to its prepregnancy state or as complications of the labor and delivery process. These changes include those in the reproductive, urinary, cardiovascular, GI, and endocrine systems. In addition, postpartum hemorrhage, postpartum fever, and psychiatric disorders are common complications during this time frame. Because of the complexity and clinical importance of these topics, they are each discussed in separate concept articles.
Endometritis is an inflammation of the endometrium, the inner layer of the uterus. The most common subtype is postpartum endometritis, resulting from the ascension of normal vaginal flora to the previously aseptic uterus. The 2nd subtype is endometritis unrelated to pregnancy, which is further subdivided into acute and chronic forms. Pelvic inflammatory disease usually precedes acute endometritis, while the chronic form is often idiopathic but may be associated with chlamydia, tuberculosis, radiation therapy, or intrauterine devices. Clinical features include fever, abdominal pain, abnormal vaginal bleeding, and vaginal discharge. Diagnosis is based on history and physical examination. Imaging is performed to exclude abscesses, septic pelvic thrombophlebitis, and retained products of conception. Management includes hydration and antibiotic therapy.
Benzodiazepines work on the gamma-aminobutyric acid type A (GABAA) receptor to produce inhibitory effects on the CNS. Benzodiazepines do not mimic GABA, the main inhibitory neurotransmitter in humans, but instead potentiate GABA activity. The drug class of benzodiazepines has anxiolytic, muscle-relaxant, hypnotic, sedative, and anticonvulsant properties. These agents are not generally recommended for long-term use, as patients can develop physiological and psychological dependence. Side effects may include cognitive impairment, somnolence, and respiratory depression.
A dislocation of the knee (tibiofemoral joint) is a rare injury but is important to recognize because of limb-threatening trauma. Knee dislocations (KDs) are emergent cases that require immediate reduction and evaluation of the neurovascular system. Clinical presentation includes precedent trauma, obvious deformity, effusion, ecchymosis, and possible signs of vascular injury to the popliteal artery. Management includes reduction of the dislocation, serial examinations for arterial perfusion, imaging of the vascular system, and orthopedic and vascular consultations.
Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ≤ 5 cm or a single deep pocket (SDP) of < 2 cm in the 2nd or 3rd trimester. Etiologies include uteroplacental insufficiency, drugs, fetal malformations (especially related to the renal/urinary systems), fetal chromosomal abnormalities, and maternal "toxoplasmosis, other agents, rubella, cytomegalovirus, and herpes simplex" (TORCH) infections. Management involves close antenatal monitoring. Complications include pulmonary hypoplasia, preterm delivery, and musculoskeletal deformities due to prolonged compression. Oligohydramnios is also frequently associated with growth restriction and fetal intolerance to labor, necessitating cesarean delivery. Prognosis is extremely poor when diagnosed in the 1st and 2nd trimesters, but generally favorable in the 3rd trimester.
Congenital malformations of the female reproductive system are any congenital anomalies that affect the ovaries, fallopian tubes, uterus, cervix, hymen, and/or vulva. Any of these anomalies can affect the normal reproductive and sexual functions of affected women. The cause is usually unknown. Clinically, these patients typically present with menstrual and/or fertility issues, with the exact presentation varying based on the patient’s anatomy. Diagnosis is primarily based on history, physical examination, and imaging with pelvic ultrasonography and/or pelvic MRI. Management depends on the type of defect(s) present and often involves surgical correction and/or hormone replacement. Most malformations can be managed well and have a good prognosis. Associated complications are infertility and the psychosocial and emotional impact of having “abnormal” genitalia.
Cerebral palsy (CP) refers to a group of conditions resulting in motor impairment affecting tone and posture and limiting physical activity. Cerebral palsy is the most common cause of childhood disability. It is caused by a nonprogressive CNS injury to the fetal or infant brain. It is classified according to muscle tone, its distribution, and the presumed time of injury (spastic diplegia is the most common), and it is present in around 3 per 1,000 live births. Diagnosis is made by a detailed history and physical exam with an MRI scan confirming CNS insult. Interventions are multidisciplinary and prognosis depends on the degree of disability.
Normal placental structure and function are essential for a healthy pregnancy. Some of the most common placental abnormalities include structural anomalies (such as a succenturiate lobe or velamentous cord insertion), implantation anomalies (such as placenta accreta and placenta previa), and functional anomalies (such as placental insufficiency). The placenta is typically seen well on ultrasound, and placental assessment is part of routine antenatal screening, which is when most structural and implantation anomalies are identified. Because of the extensive maternal and fetal circulation through the placenta, placental abnormalities can significantly increase the risk of serious antepartum or postpartum hemorrhage. Placental abnormalities also frequently impact decisions regarding the timing and route of delivery.
Iron deficiency anemia is the most common type of anemia worldwide. This form of anemia is caused by insufficient iron due to a decreased supply, an increased loss, or an increased demand. Iron deficiency anemia is seen across all ages, sexes, and socioeconomic strata; however, children, women of childbearing age, and patients from lower socioeconomic strata are at higher risk. Symptoms include pallor, particularly of the mucous membranes, easy fatigability, and headaches. Iron studies are the key to diagnosis. Treatment is based on the underlying cause of iron deficiency and consists of supplementation.
Renin-angiotensin-aldosterone system inhibitors constitute an important drug class for the treatment of cardiovascular disease. They are 1st-line antihypertensive agents, in addition to being used in the treatment of MI, heart failure, diabetic nephropathy, and stroke. Renin-angiotensin-aldosterone system inhibitors include ACEis, ARBs, direct renin inhibitors (DRIs), angiotensin receptor and neprilysin inhibitors (ARNIs), and aldosterone antagonists, which affect different components of the RAAS pathway. In general, the use of RAAS inhibitors results in decreased vasoconstriction and serum blood volume. Common adverse effects include hyperkalemia, cough, angioedema, and pancreatitis, which are all more common with the use of ACEis than ARBs.
During pregnancy, fetal development and growth are sustained completely by the mother until birth. The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. The placenta is also called “the fetal lung” because it allows for gas exchange between the maternal and fetal circulation. Diseases or defects in the placenta often have severe, and even fatal, complications.
The hepatitis E virus (HEV) is a small nonenveloped virus that contains linear, single-stranded, positive-sense RNA, making it similar to norovirus. Transmission of HEV is via the fecal–oral route and is clinically similar to that of hepatitis A. However, unlike hepatitis A, hepatitis E is quite severe, especially in pregnant women, and may cause fulminant hepatitis along with hepatic encephalopathy over a period of approximately 8 weeks. Management is mainly preventive and includes avoiding contaminated drinking water, good sanitation, and adequate personal hygiene.
Ovarian torsion is a clinical emergency in which the ovaries (with or without the fallopian tubes) twist along their axis, leading to partial or complete obstruction of their blood supply. Ovarian torsion is also called adnexal or tubo-ovarian torsion, especially if a fallopian tube is also involved. The twisting of the ovaries occurs along the suspensory ligament of the ovary (or infundibulopelvic ligament) and the utero-ovarian ligament (or just ovarian ligament), which support the ovaries and secure them to the uterus and inner pelvic walls. It occurs in women of reproductive age and in cases of ovaries > 5 cm. The torsion cuts off the ovarian blood supply, leading to pooling of blood, edema, and severe pain. As a clinical emergency, it needs to be treated promptly. Failure in early management by surgical intervention can lead to necrosis of the ovaries and infertility.
The abdominal examination is the portion of the physical exam evaluating the abdomen for signs of disease. The abdominal examination consists of inspection, auscultation, percussion, and palpation. Along with information from the history, the information gathered from the physical examination of the abdomen is used by the physician to generate a differential diagnosis and treatment plan for the patient.
The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. The vertebral column is the foundation for the trunk, provides an attachment for muscles and ligaments, and protects the spinal cord and nerve roots.
Macrolides and ketolides are antibiotics that inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit and blocking transpeptidation. These antibiotics have a broad spectrum of antimicrobial activity but are best known for their coverage of atypical microorganisms. Common macrolides are erythromycin, clarithromycin, and azithromycin. Side effects include GI upset, QT prolongation, and hepatotoxicity. Resistance mechanisms include ribosomal methylation or mutation, inactivation of the drug through enzyme production, or removal of the drug through efflux pumps.
Worldwide, the most frequent cause of death is heart disease. Thus, the common conditions that are evaluated in healthcare facilities are often related to the heart or the cardiovascular system: hypertension, atherosclerotic disease, and heart failure. In radiologic terms, this region is likely the most frequently studied aspect of human anatomy in healthcare delivery settings. Multiple methods are used, including X-ray, CT, MRI, echocardiography, nuclear imaging, and angiography. Each test has its advantages and disadvantages and is obtained on the basis of the clinical presentation, acuity of symptoms, and risks and benefits to the patient. It is important to know the roles of imaging studies to help determine the proper treatment.
Child abuse is an act or failure to act that results in harm to a child’s health or development. The abuse encompasses neglect as well as physical, sexual, and emotional harm. Seen in all subsets of society, child abuse is a cause of significant morbidity and mortality in the pediatric population. Diagnosis is made with a thorough interrogation of events and physical examination, and treatment is multidisciplinary and long term. Physicians are legally mandated to report all cases of abuse.
The abdominal cavity has a complex and intricate anatomy. A physician must know in which area of the abdomen every major structure is located to understand the clinical presentation of abdominal pathologies and/or in trauma situations to estimate which organs are most likely injured. The general surgeon, especially in emergency situations, uses this knowledge to execute the most advantageous surgical approach for a particular situation.
Nonsteroidal antiinflammatory drugs (NSAIDs) are a class of medications consisting of aspirin, reversible NSAIDs, and selective NSAIDs. NSAIDs are used as antiplatelet, analgesic, antipyretic, and antiinflammatory agents. Common side effects include GI irritation, prolonged bleeding, and AKI.
Scoliosis is a structural alteration of the vertebral column characterized by a lateral spinal curvature of greater than 10 degrees in the coronal plane. Scoliosis can be classified as idiopathic (in most cases) or secondary to underlying conditions. Other classifications are according to etiology, location, and severity. Patients present with spinal asymmetry and often have associated pain. Diagnosis is initially clinical and is confirmed later by X-ray. Management can be conservative or surgical, depending on the severity.
Major depressive disorder (MDD), commonly called depression, is a unipolar mood disorder characterized by persistent low mood and loss of interest in association with somatic symptoms for a duration of ≥ 2 weeks. Major depressive disorder has the highest lifetime prevalence among all psychiatric disorders. Biologic, psychosocial, and genetic factors contribute to depression. Treatment methods include pharmacotherapy, psychotherapy, and neuromodulation therapies such as electroconvulsive therapy (ECT). The leading cause of death associated with MDD is suicide, which is more common in the elderly population.
Hypertensive disorders of pregnancy include chronic hypertension, preeclampsia/eclampsia, gestational hypertension, and hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome. These syndromes pose a significant risk to the pregnant woman and her fetus. Hypertension is defined as a BP > 140/90 mm Hg and can be diagnosed before (chronic) or after (gestational) the 20th week of gestation. Preeclampsia is gestational hypertension with proteinuria or end-organ damage. Eclampsia is preeclampsia with seizures. HELLP syndrome is a severe manifestation of preeclampsia leading to hemolysis, low platelets, and liver injury. Management is with antihypertensives and magnesium sulfate for seizure prophylaxis. The definitive treatment for all hypertensive disorders of pregnancy is delivery.
Alpha-1 antitrypsin deficiency is a genetic disorder caused by inherited genetic mutations of the SERPINA1 gene, causing the defective production of the protease inhibitor alpha-1 antitrypsin (AAT). These mutations can lead to deficiency of the enzyme causing lung disease, production of an abnormal form of the enzyme leading to liver dysfunction, or both. Patients commonly present with emphysema, spontaneous pneumothorax, cirrhosis, hepatitis, or hepatocellular carcinoma. There is no known cure. Management is supportive and includes infusion of AAT, treatment of comorbidities, and liver transplantation. Prognosis may vary based on the form of disease contracted and the severity of symptoms.
Infertility is the inability to conceive in the context of regular intercourse. The most common causes of infertility in women are related to ovulatory dysfunction or tubal obstruction, whereas, in men, abnormal sperm is a common cause. Diagnosis of infertility involves laboratory assessments for ovulatory function and a hysterosalpingogram to determine tubal patency in women, and semen analysis to assess the condition in men. Management involves treatment of the underlying pathology when possible, and may include ovulation induction with either timed intercourse or intrauterine insemination (IUI), in vitro fertilization (IVF), and donor gametes, or by gestational surrogates or adoption.
Labor can be extremely painful, and adequate pain management during labor and delivery is an important part of obstetric care. Appropriate therapy should be administered based on patient preference and medical need. Both pharmacological and non-pharmacological pain control options are available. Maternal request alone is sufficient indication for pharmacologic pain management. Options include systemic analgesics, including inhaled nitrous oxide and opioids, as well as local and regional techniques, including pudendal nerve blocks, epidural, and spinal anesthesia. In truly emergent situations requiring urgent cesarean delivery, general anesthesia can also be used.
Delirium is a medical condition characterized by acute disturbances in attention and awareness. Symptoms may fluctuate during the course of a day and involve memory deficits and disorientation. There are many causes of delirium. Early recognition and accurate diagnosis constitute the 1st steps to adequate management. The primary goal of treatment is to identify and reverse the underlying cause and prevent future episodes. Pharmacotherapy is reserved for the most severe cases of agitation.
Fetal presentation describes which part of the fetus will enter through the cervix first, while position is the orientation of the fetus compared to the maternal bony pelvis. Presentations include vertex (the fetal occiput will present through the cervix first), face, brow, shoulder, and breech. If a fetal limb is presenting next to the presenting part (e.g., the hand is next to the head), this is known as a compound presentation. Malpresentation refers to any presentation other than vertex, with the most common being breech presentations. Vaginal delivery of a breech infant increases the risk for head entrapment and hypoxia, so, especially in the United States, mothers are generally offered a procedure to help manually rotate the baby to a head-down position instead (known as an external cephalic version) or a planned cesarean delivery.
Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. There are several different types of skin and uterine incisions that can be made during the procedure, but the most common combination is a Pfannenstiel skin incision with a low transverse uterine incision. Complication rates are generally higher with a CD than with an uncomplicated vaginal delivery, which is why unnecessary CDs should be avoided. Postpartum care for these women combines routine postpartum care with routine postoperative care.
The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. The primary indication for use is treatment of urinary tract infection (although significant resistance has emerged). In addition, the drugs are used to treat and prevent opportunistic infections such as toxoplasmosis encephalitis and pneumocystis pneumonia in immunosuppressed individuals. The most common adverse events are hypersensitivity reactions, fever, rash, GI upset, and hematologic reactions. The drugs are generally contraindicated in pregnancy, young/ill infants, and individuals with megaloblastic anemia or severe renal impairment.
Ovarian cysts are defined as collections of fluid or semiliquid material, often walled off by a membrane, located in the ovary. These cysts are broadly categorized as either functional or neoplastic. Neoplastic ovarian cysts are subcategorized as either benign or malignant. When the cysts occur as a result of normal physiologic processes, they are called functional, whereas if there is abnormal growth of ovarian cells, the cyst is referred to as neoplastic. In women of reproductive age, neoplastic ovarian cysts are typically benign; however, the risk of malignancy increases in the postmenopausal period. While most ovarian cysts do not cause symptoms, some women report vague symptoms such as lower abdominal pain or abdominal fullness. Complications of functional cysts include torsion and rupture. Neoplastic cysts may be either benign or cancerous. A diagnosis of ovarian cancer requires consultation with a specialist because treatment involves coordination of surgery and chemotherapy. Treatment is dependent on the etiology of the ovarian cyst and may range from surgical intervention to supportive care only.
Hirschsprung disease (HD), also known as congenital aganglionosis or congenital megacolon, is a congenital anomaly of the colon caused by the failure of neural crest-derived ganglion cells to migrate into the distal colon. The lack of innervation always involves the rectum and extends proximally and contiguously over variable distances. Most cases are diagnosed in the neonatal period, with a classic triad of symptoms including delayed passage of meconium, abdominal distension, and bilious vomiting. Individuals having less severe degrees of functional obstruction may not be diagnosed until later in infancy or childhood when they present with symptoms of chronic refractory constipation, abdominal distension, and failure to thrive. The diagnosis of HD is confirmed by the absence of ganglion cells on rectal biopsy after noninvasive testing such as anorectal manometry and the use of contrast enema. Surgical resection of the aganglionic segment is the standard treatment.
Acetaminophen is an over-the-counter nonopioid analgesic and antipyretic medication and the most commonly used analgesic worldwide. Despite the widespread use of acetaminophen, its mechanism of action is not entirely understood. However, acetaminophen is believed to exert its effects through indirect and reversible inhibition of cyclooxygenase (COX)-1 and COX-2. The effects are generally limited to the CNS. Acetaminophen is primarily metabolized by the liver; therefore, an overdose can lead to life-threatening hepatotoxicity. In adults, limiting the total acetaminophen dose (from all sources and routes) to < 4000 mg/day is highly recommended. Contraindications to acetaminophen use include hypersensitivity, severe hepatic impairment, or severe active hepatic disease.
Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. There are numerous maternal adaptations to pregnancy, both anatomic and physiologic, which occur to help support the developing fetus and prepare the mother's body for ultimate delivery. Pregnancy is not a pathologic condition, but good routine prenatal care can help achieve the best outcomes for both the mother and infant. Prenatal care includes appropriate lab and ultrasound testing, anticipatory guidance, and offering solutions or advice for common pregnancy discomforts.
The head and neck examination is the portion of the physical examination done to observe for signs of head and neck disease or illness. The head and neck examination consists of inspection, palpation, and auscultation. The information gathered from the physical examination of the head and neck, along with the information from the history, is used by the physician to generate a differential diagnosis and treatment plan for the patient.
Pancreatic cancer, consisting mostly of invasive pancreatic ductal adenocarcinoma (PDAC), arises from the ductal cells of the exocrine pancreas and is the 4th leading cause of cancer-related deaths in the United States. Pancreatic cancer has the highest mortality rate among the major cancers, with a 5-year survival rate of only 8%–10%. Clinical presentation includes symptoms of abdominal pain, jaundice, and weight loss. Diagnosis is made by CT, MRI, and endoscopic ultrasonography (EUS). Management by surgical resection, usually with neoadjuvant or adjuvant chemotherapy, provides the only chance for cure in the 15%–20% of patients who have resectable disease at the time of diagnosis. Other rare malignant tumors arising from the exocrine pancreas are acinar cell carcinoma and pancreatoblastoma.
Pancreatic neuroendocrine tumors (PanNETs) arise from the endocrine pancreas (islet cells) and represent 2%–5% of primary pancreatic neoplasms; the other 95%–98% of pancreatic neoplasms are from the exocrine pancreas. The majority of PanNETs are nonfunctional (50%–75%), while others that are functional may be benign or malignant. Benign or malignant PanNETs include insulinomas, gastrinomas, malignant pancreatic neuroendocrine carcinomas, and very rare tumors named glucagonomas, somatostatinomas, and VIPomas, after the hormones they secrete. Diagnosis is made clinically, with lab testing for hormone secretion, as well as imaging or upper endoscopy. Management is surgical or with newer molecularly targeted therapies.
Hypokalemia is defined as plasma potassium (K+) concentration < 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5–5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake. If minor in severity, hypokalemia is usually asymptomatic. However, acute reductions in K+ level or severe hypokalemia can lead to cardiac arrhythmias, muscle weakness, rhabdomyolysis, paralysis, and respiratory failure. Diagnosis is by clinical history and lab testing. Management is guided by severity and includes treating urgent symptoms, replacing the K+ deficit, and treating the underlying cause.
The hepatitis A virus (HAV) is a nonenveloped virus of the Picornaviridae family with single-stranded RNA. The virus replicates in the liver, is excreted in the bile, and is found in high concentrations in the stool of acutely infected individuals. The 2 main routes of infection are consumption of contaminated food or water and direct contact with an infected person. HAV causes an acute, highly contagious hepatitis with unspecific prodromal symptoms such as fever and malaise followed by jaundice and elevated liver transaminases. Most individuals recover fully within a few months, and the immunity resulting from HAV infection is lifelong. Unlike hepatitis B and C, HAV infection does not result in chronic infection or chronic liver disease. Preventive vaccination is available for HAV and is recommended for individuals with increased risk of exposure and, in some countries such as the United States, for all children > 12 months of age.
Gastric acid medications include proton pump inhibitors (PPIs) and H₂ receptor antagonists (also known as H₂ blockers). The drugs work through different mechanisms to suppress acid secretion by parietal cells in the stomach. The most common indications include peptic ulcer disease, GERD, and dyspepsia. Adverse effects of PPIs include malabsorption, acute interstitial nephritis, and an increased risk of Clostridioides difficile infection. Adverse effects of H₂ blockers include CNS effects, bradycardia/hypotension, gynecomastia, and galactorrhea. Both classes are associated with drug interactions related to the cytochrome P450 system.
Puberty is a complex series of physical, psychosocial, and cognitive transitions usually experienced by adolescents (11–19 years of age). Puberty is marked by a growth in stature and the development of secondary sexual characteristics, achievement of fertility, and changes in most body systems. Being familiar with normal puberty is important to be able to recognize and manage abnormalities such as precocious puberty or delayed puberty.
Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Uremia refers specifically to the constellation of symptoms that occur with severe renal dysfunction. The etiologies of AKI are classified as prerenal, intrinsic renal, or post-renal, and there is a varied clinical presentation depending on the severity of kidney dysfunction. Acute kidney injury is diagnosed initially by a change in serum creatinine levels, and then the etiology is determined by clinical history, lab testing, imaging, and possibly kidney biopsy. The management of AKI depends on the etiology; however, attention to the individual's volume status and serum electrolytes is always important. If management is unsuccessful and AKI progresses to CKD, then renal replacement therapy with dialysis or kidney transplantation is necessary.
Alcohol is one of the most commonly used addictive substances in the world. Alcohol use disorder (AUD) is defined as pathologic consumption of alcohol leading to impaired daily functioning. Acute alcohol intoxication presents with impairment in speech and motor functions and can be managed in most cases with supportive care. Withdrawal from chronic alcohol use can have fatal consequences, including delirium and seizures, and is managed with benzodiazepines. Chronic AUD affects almost every part of the human body and has serious impacts on a person’s mental and physical health. Alcohol user disorder can be managed with psychotherapy as well as medications; however, the prognosis is usually poor, with high rates of relapse and complications.
Colon polyps are growths of mucosal tissue in the colon, the most common site of polyps in the GI tract. Polyps can be classified as neoplastic or nonneoplastic and may be associated with genetic syndromes. Hyperplastic polyps are nonneoplastic and are the most common type overall, whereas adenomas are the most common type of neoplastic polyp and have the potential to progress to cancer. For most people without hereditary syndromes, colon cancer screening should begin at age 50 (at age 45 for Black individuals) and in adolescence for those with the rare familial adenomatous polyposis (FAP) syndrome. Diagnosis is by biopsy, and management includes frequent surveillance in people with adenomatous polyps or screening every 10 years in the general population until age 75.
Tension headache is the most common of the primary primary headache disorders and one of the most common disorders presenting for medical evaluation worldwide. Tension headaches are generally described as bilateral, nonthrobbing, and of mild to moderate severity. There is no aura or other associated features. The diagnosis is clinical, often self-diagnosed by the patient or in the primary care setting. Management consists of abortive analgesics, such as NSAIDs and aspirin for isolated attacks, and preventative measures, such as behavioral changes, biofeedback, and preventative administration of medication for more chronic attacks.
Cluster headache is a primary headache disorder characterized by moderate-to-severe unilateral headaches that occur in conjunction with autonomic symptoms. Cluster headache can last from weeks to months, during which the affected individual may experience attacks up to several times a day, followed by a pain-free remission period. Autonomic symptoms typically manifest as ocular and nasal phenomena (e.g., ptosis, miosis, nasal congestion, rhinorrhea) on the same side as the headache. Men are more commonly affected by cluster headaches than women. The diagnosis is clinical and often easy to establish owing to the distinct features of the presenting headache. The 1st-line treatment involves administration of oxygen by nasal cannula and/or abortive therapy using a triptan. Preventative strategies (e.g., glucortoicoids, verapamil) are crucial, as cluster headache is a chronic condition associated with significant morbidity and a high rate of suicide.
Hormones are messenger molecules that are synthesized in one part of the body and move through the bloodstream to exert specific regulatory effects on another part of the body. Hormones play critical roles in coordinating cellular activities throughout the body in response to the constant changes in both the internal and external environments. The work of hormones allows the body to maintain homeostasis and regulate growth and development. Hormones are typically either made from amino acids or derived from cholesterol (the latter group being known as steroid hormones). Hormones exert their effects by binding to receptors either on the cell surface (most amino acid–based hormones) or within the cytosol (steroid hormones). Ultimately, binding to receptors triggers changes in gene expression or enzymatic activity within the cell.
Sexual physiology and development begin in early childhood and represent a complex process of events that lead to the final development of sexual orientation and behavior. Sexual behavior and interactions include several changes that are quite different between males and females.
A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Diagnosis is clinical, relying on history and physical exam, but also may use EEG and other tools. Management includes both abortive and preventive medications but may not be required in self-limited cases with no etiology found during workup.
Antidiarrheal agents include several drug classes, including opioid agonists, somatostatin analogues, adsorbents, and bile acid sequestrants. These medications mainly work through antimotility and/or antisecretory effects. Somatostatin analogues are particularly helpful for secretory diarrhea due to endocrine hormone-producing malignancies, while bile acid sequestrants can be used for conditions causing bile acid malabsorption diarrhea. Antidiarrheals can decrease the clearance of infectious pathogens and toxins and should be avoided in invasive infectious diarrhea.
Obstetric imaging refers to imaging of the female reproductive tract and developing fetus during pregnancy. Ultrasonography is the 1st-line imaging modality during pregnancy as it does not emit radiation; thus, it is the safest option for the developing fetus. Obstetricians depend heavily on ultrasound for the detection, monitoring, and assessment of several maternal and fetal conditions without radiation exposure. For example, congenital fetal anomalies, abnormal placentation, poor fetal growth, and abnormal fluid volumes can all be thoroughly assessed using ultrasound. Radiation-emitting imaging modalities (X-ray, CT) are typically reserved for nonobstetric emergency situations.
Focused assessment with sonography for trauma is a point-of-care ultrasound examination protocol for the abdominal and thoracic cavities performed in the emergency room as part of the secondary survey in advanced trauma life support. The main goal of the FAST exam is to identify free intraperitoneal fluid (blood) and pericardial effusion from trauma. As FAST requires only an ultrasound machine at the bedside and an experienced sonographer, it is widely available, quicker, and less invasive than other image modalities. Focused assessment with sonography for trauma has largely replaced diagnostic peritoneal lavage.
An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. The clinical presentation includes neurologic symptoms with varying degrees of motor and sensory loss corresponding to the area of the brain that is affected and the extent of tissue damage. Diagnosis is made by physical examination and imaging. Management is ideally with thrombolytic therapy to restore blood flow, depending on the time frame and clinical situation. Long-term rehabilitation with physical, occupational, and speech therapies is important after the acute event.
Migraine headache is a primary headache disorder and is among the most prevalent disorders in the world. Migraine is characterized by episodic, moderate to severe headaches that may be associated with increased sensitivity to light and sound, as well as nausea and/or vomiting. A migraine attack might be preceded by a so-called aura—neurologic phenomena of visual, auditory, sensual, or motor quality. There is a strong hereditary component in the etiology of migraines. Migraine headache is a clinical diagnosis with several variants. Management strategies include abortive therapy such as NSAIDs and triptans to manage acute episodes as well as preventive strategies to minimize morbidity and pain-related disability.
Ventricular tachycardia is any heart rhythm faster than 100 beats/min, with 3 or more irregular beats in a row, arising distal to the bundle of His. Ventricular tachycardia is the most common form of wide-complex tachycardia, and it is associated with a high mortality rate. Ventricular tachycardia is often caused by myocardial ischemia, structural disease, congenital conditions, or electrolyte derangement. Individuals may present with chest pain, dyspnea, palpitations, syncope, and hemodynamic instability. Diagnosis is based on characteristic ECG findings of wide-complex QRS, fusion, and capture beats. Management may require antiarrhythmic medications or electrical cardioversion to avoid complications such as heart failure, multiorgan failure, and cardiac arrest.
The vulva is the external genitalia of the female and includes the mons pubis, labia majora, labia minora, clitoris, vestibule, vestibular bulb, and greater vestibular glands. The vagina is the female genital canal, extending from the vulva externally to the cervix uteri internally. The structures have sexual, reproductive, and urinary functions and a rich blood supply, mainly arising from the internal iliac artery.
Hepatitis D virus (HDV) is a small enveloped, single-stranded RNA virus. Hepatitis D virus is considered a satellite virus, as it requires the presence of hepatitis B virus (HBV) for assembly and secretion. Therefore, in order for an individual to contract hepatitis D, coinfection or superinfection with HBV is required. Like HBV, HDV is transmitted parenterally, through unprotected sexual intercourse, or perinatally. Clinical presentation is that of a classical viral hepatitis, including coinfection of HDV and HBV, which is considered the most serious form of hepatitis because of the high mortality rate. For acute cases, management is supportive, whereas for chronic cases, pegylated interferon alfa (PEG-IFN-α) is needed.
Local anesthetics are a group of pharmacological agents that reversibly block the conduction of impulses in electrically excitable tissues. Local anesthetics are used in clinical practice to induce a state of local or regional anesthesia by blocking sodium channels and inhibiting the conduction of painful stimuli via afferent nerves. The effects of local anesthetics are influenced by their physicochemical properties such as lipid solubility and protein binding, as well as nerve anatomy and local tissue conditions. Adverse events, interactions, and contraindications vary depending on the agent that is used.
Sepsis is defined as a life-threatening systemic response syndrome caused by viruses, bacteria, fungi, and parasites, or toxins released from these organisms. Neonates and children are particularly prone to sepsis owing to their immature immune systems. Affected individuals may present with localizing symptoms specific to a source of infection but may often complain of nonspecific systemic symptoms. Diagnosis is based on history, exam, laboratory testing, and imaging studies. A high index of suspicion, rapid diagnosis, and clinical intervention with appropriate therapy are mandatory to achieve favorable outcomes.
Transient ischemic attack (TIA) is a temporary episode of neurologic dysfunction caused by ischemia without infarction that resolves completely when blood supply is restored. Transient ischemic attack is a neurologic emergency that warrants urgent medical attention. A “tissue-based” definition is currently used rather than the former time-based limit of symptoms lasting less than 24 hours. The causes of TIA may be small clots or thromboemboli imposed on a blood vessel compromised by atherosclerosis, inflammation, or amyloid; inadequate cerebral blood flow from vasoconstriction; or severe hypotension. The clinical presentation includes transient neurologic deficits that resolve spontaneously. Management includes the reduction of risk factors to decrease the risk of a future stroke.
Brain death is a legal and clinical term describing the irreversible cessation of all cerebral and brainstem functions, including the ability of the brain stem to regulate vegetative and respiratory activities. Brain death can be due to a variety of etiologies causing catastrophic injuries to the brain, including brain ischemia due to cardiopulmonary arrest, drugs, sepsis, and trauma. The diagnosis is made at the bedside based on the clinical context and performance of a neurological exam. Additional ancillary studies may be needed to support the diagnosis and diagnostic criteria may vary among states and countries. A diagnosis of brain death must be established prior to consideration of organ donation.
Epilepsy is a chronic brain disorder marked by recurrent and unprovoked seizures. These seizures can be classified as focal or generalized and idiopathic or secondary to another condition. Clinical presentation correlates to the classification of the epileptic disorder. Diagnosis is confirmed with EEG. While some epileptic disorders resolve over time, many require lifelong antiepileptic medication for management or, in some refractory cases, surgical procedures.
Acetaminophen (APAP) is an over-the-counter nonopioid analgesic and antipyretic medication. Acetaminophen is the most commonly used analgesic worldwide. Acetaminophen overdose is also one of the most common causes of medication poisoning and death. Because APAP is primarily metabolized by the liver, overdose can lead to life threatening hepatotoxicity. In adults, limitation of total APAP dose (from all sources and routes) to < 4,000 mg per day is recommended. During evaluation, a thorough history and measurement of serum APAP are important, as the initial clinical stages of APAP overdose can be nonspecific. Management of overdose includes drug serum concentration, stabilization, decontamination, and administration of N-acetylcysteine (NAC). Use of NAC within 8 hours of ingestion is associated with good case outcomes. Without treatment, however, cases are at significant risk of severe hepatotoxicity and potentially death.
The pituitary gland, also known as the hypophysis, is considered the “master endocrine gland” because it releases hormones that regulate the activity of multiple major endocrine organs in the body. The gland sits on the sella turcica, just below the hypothalamus, which is the primary regulator of the pituitary gland. The pituitary gland has 2 lobes: the anterior lobe (the adenohypophysis) and the posterior lobe (the neurohypophysis). Each lobe has its own regulation, set of secretory products, and feedback loops. Abnormalities in the pituitary gland can lead to a wide range of clinical conditions, some of which include hyperprolactinemia, acromegaly, hyperthyroidism or hypothyroidism, and central diabetes insipidus.
High-risk headaches, sometimes also referred to as red-flag headaches, encompass secondary causes of headache that can result in irreversible end-organ damage, neurologic deficits, loss of vision, and even death. Entities such as subarachnoid hemorrhage, meningitis/encephalitis, and intracranial tumors carry high morbidity and mortality risks if not recognized and treated immediately. Diagnosis of a high-risk headache requires a high degree of clinical suspicion and is made by conducting a thorough clinical evaluation followed by a targeted workup for the most likely etiology. Management depends on the etiology but consists of prompt treatment of the underlying cause and stabilization of accompanying organ dysfunction.
Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. When you encounter a patient with chest pain, eliminating life-threatening causes, such as acute coronary syndrome (ACS) and pulmonary embolism, should be a priority. A thorough history and examination should be performed to narrow the differential diagnosis and guide diagnostic workup and management.
The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck, spanning the regions between the C5 and T1 vertebrae and encircling the anterolateral trachea. The left and right lobes of the thyroid gland are connected by a central isthmus. Important processes in metabolism, growth, cardiac function, and calcium homeostasis are regulated by the thyroid hormones (thyroxine and triiodothyronine) and calcitonin.
The gonadal hormones are produced by the human gonads: the testes and the ovaries. The primary hormones produced by these organs include androgens, estrogens, and progestins. Testosterone is the primary androgen, and it plays a critical role in the development of the primary and secondary male sex characteristics as well as of spermatogenesis. Estradiol and progesterone are the primary female hormones, which are responsible for egg development, the menstrual cycle, and breast development. The gonadal hormones are part of the hypothalamic-pituitary-gonadal (HPG) axis and are regulated by the pituitary hormones follicle-stimulating hormone (FSH) and luteinizing hormone (LH). In turn, FSH and LH are both regulated by gonadotropin-releasing hormone (GnRH) secreted from the hypothalamus.
Class 2 antiarrhythmics include beta-blockers, which exert their therapeutic effects by blocking epinephrine and norepinephrine from binding to the beta-adrenergic receptors in cardiac tissue. The outcome is an antiarrhythmic effect, which results from decreased sinoatrial node activity and increased atrioventricular conduction time and refractory period. Additional effects include decreased cardiac contractility, afterload, and blood pressure. Class 2 antiarrhythmics are used in the management of atrial fibrillation, atrial flutter, supraventricular tachycardia, and ventricular arrhythmias. Adverse effects include bradycardia, hypotension, bronchospasm, fluid retention, and fatigue. Beta-blockers should not be used in individuals with decompensated heart failure, shock, and severe bradycardia.
Abdominal and cardiac evaluation with sonography in shock (ACES) and rapid ultrasound for shock and hypotension (RUSH) are point-of-care ultrasound (POCUS) examinations indicated in cases of nontraumatic, undifferentiated hypotension, or shock. In hypotension, early diagnosis and goal-directed therapy are essential for optimal outcomes and lead to decreased mortality. Both ACES and RUSH protocols examine the chest and abdominal cavities by ultrasound in order to rapidly evaluate for reversible causes of shock and improve an accurate diagnosis. Each of these protocols combines many of the same core ultrasound elements, differing mainly in the exam sequence.
The hypothalamus is a collection of various nuclei within the diencephalon in the center of the brain. The hypothalamus plays a vital role in endocrine regulation as the primary regulator of the pituitary gland, and it is the major point of integration between the central nervous and endocrine systems. Different nuclei within the hypothalamus play roles in hormone regulation and secretion, autonomic regulation, thermoregulation, food and water intake, sleep and circadian rhythms, memory, and emotional behavior. The hypothalamus has both neural and circulatory connections with the pituitary gland. Abnormalities in the hypothalamus can lead to a wide range of clinical conditions.
Penetrating abdominal injuries are created by an object puncturing the abdominal wall. Injuries can be high velocity, like gunshot wounds, or low velocity, like stab wounds. Different structures can be injured, including the duodenum, spleen, liver, kidneys, and pelvic organs. The extent and specific type of abdominal traumatic injury can be identified by a proper history and physical exam and supported by appropriate imaging studies. Management, which can be laparotomy or a conservative approach, is dependent on the patient’s hemodynamic stability and specific type of injury.
As a general term, headache is a descriptor tied to hundreds of clinical entities. A headache is one of the most common reasons people present for medical attention. All headaches fall into 1 of 2 classification systems; primary and secondary headache syndromes. The presentation, degree of severity, underlying pathogenesis, potential clinical sequelae, management, and prognosis are as variable as the underlying headache entities.
Diffuse proliferative glomerulonephritis (DPGN) is a histopathologic classification of glomerulonephritis (GN) characterized by an increased cellular proliferation affecting > 50% of the glomeruli. Mesangial, endothelial, and epithelial cells are notably increased. The most common causes are lupus nephritis class IV and IgA nephropathy. Individuals may present with symptoms related to the renal disease, such as fatigue, nausea, vomiting, hematuria, proteinuria, hypertension, and edema. Other manifestations related to the underlying disease can be present. Diagnosis is made by laboratory tests, renal imaging, and renal biopsy. Microscopic findings show hypercellularity of mesangial and endothelial cells, with capillary loop thickening. Early aggressive therapy is indicated and is based on the specific etiology.
Acute shoulder injuries are a common reason for visits to primary care physicians and EDs. Common acute shoulder injuries include acromioclavicular joint injuries, clavicle fractures, glenohumeral dislocations, proximal humerus fractures, and rotator cuff tears. Evaluation of acute shoulder pain requires an understanding of the mechanism of injury, as well as the appropriate physical examination and radiologic studies needed in the acute setting. A focused history and physical examination is essential and should include inspection, palpation, and a thorough neurovascular exam. Imaging begins with plain radiographs and is occasionally supplemented by MRI or CT imaging. Management includes pain control and varies based on diagnosis.
The penis is the male organ of copulation and micturition. The organ is composed of a root, body, and glans. The root is attached to the pubic bone by the crura penis, which are the extremities of the corpora cavernosa. The body consists of the 2 parallel corpora cavernosa and the corpus spongiosum, which sits beneath the corpora cavernosa and through which the urethra passes. The glans is ensheathed by the prepuce or foreskin. The penis is homologous with the clitoris in females.
The pancreas lies mostly posterior to the stomach and extends across the posterior abdominal wall from the duodenum on the right to the spleen on the left. The pancreas is covered with a very thin connective tissue capsule that extends inward as septa, partitioning the gland into lobules. This organ has both exocrine and endocrine tissue. The exocrine portion is organized in grape-like clusters of acini, which are small sacs surrounding the terminal ends of pancreatic ducts. The cells lining the acini and ducts secrete products that make up pancreatic juices, which play a major role in digestion. The endocrine portion of the gland consists of circular islets interspersed between acini, which secrete glucagon, insulin, and somatostatin.
Tuberous sclerosis or tuberous sclerosis complex (TSC) is an autosomal dominant disorder with mainly neurocutaneous symptoms. Mutation in the TSC genes causes excessive tumor-like growths in the brain, eyes, heart, kidney, and lungs. Cutaneous manifestations include hypopigmentation (i.e., ash leaf spots, confetti lesions) or excessive growth (i.e., angiofibroma, shagreen patch). The diagnosis is made on clinical suspicion and confirmed by genetic testing. Management entails a multidisciplinary approach that targets monitoring and treatment of the various manifestations of the disorder. mTOR inhibitors such as sirolimus and everolimus are used to treat severe manifestations.
Von Hippel-Lindau (VHL) disease is an autosomal dominant genetic condition resulting from a deletion or mutation in the VHL gene. Individuals diagnosed with VHL disease have tumors and cysts in various parts of their bodies and may present with hemangioblastomas, renal cell carcinoma (RCC), pheochromocytoma, endolymphatic sac tumors of the middle ear, pancreatic tumors, and papillary cystadenomas of the epididymis or the broad ligament. The diagnosis is by genetic testing, laboratory evaluation of BUN, laboratory evaluation for the presence of catecholamines in the blood or urine, fundoscopic exam of the eye to detect hemangioblastoma of the retina, and CT/MRI to detect any other tumors. Management of the disease includes surgical removal of tumors.
The kidneys, solid organs located in the lower back, are extremely important in regulating homeostasis through their role in maintaining blood volume, electrolyte balance, acid–base equilibrium, blood-pressure regulation, and removal of metabolic waste from the blood. Evaluation of renal function and early detection of kidney dysfunction is of primary importance. Tests of renal function are useful in identifying the presence of renal disease, monitoring the response of kidneys to treatment, and determining the progression of renal disease.
The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. On a microscopic level, the stomach wall has several layers, including a mucosa, submucosa, muscularis, and serosa. The stomach is filled with glands that secrete a variety of substances involved in the digestive process. The arterial supply to the stomach is primarily from vessels originating from the celiac trunk.
Penile anomalies and conditions may be congenital or acquired and can affect the urethral opening, prepuce, shaft, or glans or the penis. Examples include phimosis, paraphimosis, epispadias, hypospadias, balanitis, Peyronie disease, and priapism. The severity of clinical symptoms varies, but diagnosis of each of these conditions is usually based on the history and physical examination. Treatment varies from medical therapies to surgical intervention. These diagnoses are important to be aware of, since a few (such as phimosis and balanitis) are relatively common, while others (such as paraphimosis and priapism) can have severe complications if not treated in a timely fashion.
Nonhormonal contraception does not affect the reproductive hormones in women. Nonhormonal contraception includes physiological methods, barrier methods, surgical methods, or the use of a copper intrauterine device. Each method has a different mechanism and extent of efficiency in preventing pregnancy. It is important to note that most physiologic methods are associated with high failure rates. On the other hand, surgical methods are permanent and highly effective.
Microsporidia are a group of obligate intracellular organisms that were recently reclassified as fungi. Microsporidia is made up of around 15 clinically relevant species, with the most common being Enterocytozoon bieneusi. There is much we do not understand about this group of organisms, and knowledge is evolving. Microsporidia species are ubiquitous, with a wide range of reservoirs. Immunocompromised individuals (particularly those with AIDS and a CD4 count < 100 cells/µL) most commonly develop symptomatic microsporidiosis. GI diseases range from acute, self-limited watery diarrhea to chronic diarrhea causing malabsorption and wasting. Extraintestinal manifestations and dissemination can also occur, affecting the eyes, respiratory tract, brain, biliary tract, urinary tract, and/or muscles. Diagnosis occurs through identification of spores on examination of the stool. Antimicrobials, such as albendazole and fumagillin, can be used to treat infections with most microsporidia species.
Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) includes granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). All 3 diseases cause life-threatening small-vessel vasculitis with a wide range of systemic manifestations, which can involve the lungs, kidneys, skin, and heart. Diagnosis is suspected by clinical presentation and a positive cytoplasmic (c)- or perinuclear (p)-ANCA test. Biopsy of involved tissue confirms the diagnosis. Glucocorticoids and immunosuppressive therapy are the mainstays of treatment.
Bundle branch and fascicular blocks occur when the normal electrical activity in the His-Purkinje system is interrupted. These blocks can be due to many etiologies that may affect the structure of the heart or the conduction system directly. The blocks are classified into right bundle branch block, left bundle branch block, left anterior fascicular block, and left posterior fascicular block depending on the location of the disruption. Most individuals are asymptomatic. ECG will provide the diagnosis. Some common ECG findings include a prolonged QRS interval, R-wave changes, axis deviation, and (in some cases) S-wave changes. No specific treatment is indicated.
Goodpasture syndrome, also known as anti-glomerular basement membrane (GBM) disease, is an autoimmune disease characterized by circulating antibodies directed against glomerular and alveolar basement membranes. The autoantibodies are thought to be generated in response to an inciting stimulus in genetically predisposed individuals. Affected individuals present with symptoms of rapidly progressive glomerulonephritis and alveolar hemorrhage. Constitutional symptoms such as malaise, chills, fever, arthralgia, and weight loss may also be present. Detection of anti-GBM antibodies and renal biopsy findings of crescent glomerulonephritis with linear IgG deposition along the basement membranes provide the diagnosis. Management includes plasmapheresis and immunosuppressants. Renal transplantation is an option in individuals who develop end-stage renal disease.
Normal pressure hydrocephalus (NPH) is a neurodegenerative disorder characterized by the triad of gait abnormalities, dementia, and urinary urgency or incontinence. Normal pressure hydrocephalus can be either idiopathic or secondary to intraventricular or subarachnoid hemorrhage. Symptoms may be similar to those of Alzheimer and Parkinson's diseases. Diagnosis of NPH is clinical, in addition to lumbar puncture testing and neuroimaging. Management is with surgical shunt placement to drain excess CSF from the cerebral ventricles.
Hypertension, or high blood pressure, is a common disease manifesting as elevated systemic arterial pressure. Hypertension is most often asymptomatic and discovered as part of a routine physical examination, or during triage for an unrelated medical encounter. Age, gender, smoking, obesity, and diet are all contributing factors to hypertension and can lead to heart attack, stroke, congestive heart failure, and CKD if not managed properly. If blood pressure cannot be controlled with lifestyle modifications, medications are employed for the management of hypertension. The 1st-line medication classes include thiazide-like diuretics, angiotensin-converting enzyme inhibitors (ACEis), angiotensin II receptor blockers (ARBs), and calcium channel blockers (CCBs). Contraindications, adverse effects, and drug-to-drug interactions are agent specific.
The scrotum is a sac hanging outside the body that contains parts of the male reproductive system. The scrotum’s main function is to support testicles outside the body so that spermatogenesis can be completed under optimal conditions. The scrotum can be affected by various pathologic conditions, and imaging is a valuable tool in reaching the appropriate diagnosis. The most important imaging method is ultrasonography +/– Doppler mode because scrotal structures are superficial with no intervening gas. MRI is useful when ultrasound is indeterminate.
The small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. The small intestine is divided into 3 segments: the duodenum, the jejunum, and the ileum. Like the entire GI tract, the walls of the small intestine have several layers: an inner absorptive mucosal layer (which is made up of an epithelium, lamina propria, and muscularis mucosa) and submucosal, muscular, and serosal layers. The arterial supply to the small intestine is via branches of the superior mesenteric artery, and veins drain into the hepatic portal system. The small intestine is innervated by the ANS.
The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Bile is secreted by hepatocytes into thin channels called canaliculi. These canaliculi lead into slightly larger interlobular bile ductules, which are part of the portal triads at the “corners” of hepatic lobules. The bile leaves the liver via the right and left hepatic ducts, which join together to form the common hepatic duct. The common hepatic duct joins with the cystic duct to form the common bile duct, which empties into the small intestine. If the sphincters leading into the intestines are closed, bile will travel via the cystic duct into the gallbladder for storage.
Substance use disorders are a significant cause of morbidity and mortality, especially among adolescents and young adults. A substance-related and addictive disorder is the continued use of a substance despite harmful consequences; these include significant impairment to one’s health or relationships or failure to fulfill major responsibilities at work, school, or home because of substance use. There are several individual substance use disorders, and they are linked by their chronicity and the significant impairment they cause. Most substance use disorders have associated intoxication and withdrawal symptoms. Treatment options include pharmacotherapy and behavioral interventions; however, individuals with substance use disorders have frequent relapse/remission as well as low compliance with treatment.
There are 29 blood group systems, among which the ABO group is the most important. Blood groups are determined by antigens that are surface markers on the RBC and consist of proteins and carbohydrates. Antigens are also found on platelets, leukocytes, and tissue cells and also exist in soluble form in body secretions such as breast milk, seminal fluid, saliva, sweat, gastric secretions, urine, and amniotic fluid. Individuals will naturally develop antibodies (Abs) against the ABO antigens they do not have. For this reason, determining an individual’s blood group is important prior to any blood product transfusion and prior to donating or receiving an organ transplant. If appropriate matching does not happen, a massive activation of the immune system and coagulation cascade will ensue, leading to shock, organ failure, and even death.
Although fresh whole blood was the only product in the early years of transfusion, the advent of whole-blood fractionation techniques has allowed for more efficient use of the various blood components. Fractionated transfusion products, prepared in blood transfusion centers, include RBCs, platelets, FFP, and cryoprecipitate. These products are transfused for different indications and each addresses different pathologies.
Central cord syndrome (CCS) is a neurological syndrome caused by an injury to the center of the spinal cord, affecting the spinothalamic tracts ((STTs) sensory) and medial aspect of the corticospinal tracts ((CSTs) motor), most often due to trauma in patients with cervical spondylosis. A less frequent but classic cause of CCS is syringomyelia. Clinical manifestations are motor deficits in the arms more so than the legs and variable sensory deficits below the level of injury. Diagnosis is made clinically and is supported with neuroimaging. Definitive management can be medical or surgical, depending on the severity of the injury. Rehabilitation is the key to maintaining functionality and improving chances of recovery.
Anterior cord syndrome (ACS) is an incomplete cord syndrome predominantly affecting the anterior (ventral) ⅔ of the spinal cord while sparing the dorsal columns. Anterior cord syndrome can be caused by occlusion of the anterior spinal artery or by trauma, which results in disc herniation and bone fragments disrupting the spinal cord. Clinical manifestations include loss of both motor and sensory function below the level of injury. Diagnosis of ACS is by clinical exam and neuroimaging with MRI. Management is directed at resolving the underlying cause. Preservation of motor function is a priority, but the prognosis is poor.
The esophagus is a muscular tube-shaped organ of around 25 centimeters in length that connects the pharynx to the stomach. The organ extends from approximately the 6th cervical vertebra to the 11th thoracic vertebra and can be divided grossly into 3 parts: the cervical part, the thoracic part, and the abdominal part. The wall of the esophagus is made up of 4 primary layers: mucosa (lined with squamous epithelium), submucosa, a thicker muscularis layer, and an outer layer of connective tissue. The esophagus also has a sphincter at each end, which allows it to help control the passage of food into the stomach.
The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. The colon also contains many mucus-secreting glands to lubricate the stool passing through it. The colon receives its blood supply from colic branches of the superior and inferior mesenteric arteries, which form an important anastomosis along the transverse colon. The colon is regulated by the ANS and receives both sympathetic (inhibitory) and parasympathetic (stimulatory) input.
Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants are used in the treatment and prevention of thrombotic and embolic diseases including cardioembolic ischemic stroke, acute coronary syndrome, and venous thromboembolism, among other conditions. Patients with atrial fibrillation or thrombophilias may require indefinite or lifelong anticoagulation. Accordingly, the route of administration, drug interactions, pharmacokinetics, and availability of reversal factors should be considered while selecting the anticoagulant therapy.
Acute otitis media is an infection in the middle ear characterized by mucosal inflammation and retention of fluid. The most common pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The condition can present with fever, otalgia, and diminished hearing. Diagnosis is made by history and otoscopic exam showing a bulging tympanic membrane with reduced mobility. Observation or antibiotics are the usual management approaches, but surgery for tympanostomy tubes may be required if there are recurrent infections. Potential complications include hearing loss, tympanic membrane perforation, and mastoiditis.
Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary edema is easily recognized on a chest X-ray, and an evaluation should be done to identify the underlying cause. Management involves supporting the patient’s respiratory status with oxygen, diuretics, and treatment of the underlying cause.
Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. The diagnosis is based on clinical suspicion, and once suspected, immediate empiric treatment is warranted to prevent catastrophic and long-term neurologic sequelae. Encephalitis is managed with supportive measures and antiviral therapy. Focal neurologic defects are common after encephalitis, and hence, physiotherapy is usually required.
Respiratory distress syndrome (RDS), also known as hyaline membrane disease, is caused by the lack of adequate pulmonary surfactant production in an immature lung. The syndrome is most commonly seen in preterm infants. The incidence is inversely related to gestational age, with the highest risk in neonates born at less than 28 weeks. Prenatal assessment of lung maturity and steroid administration can improve outcome if an early delivery cannot be prevented. Diagnosis is clinical. Affected newborns show signs of respiratory distress at birth, or soon thereafter, with nasal flaring, grunting respirations, and retractions. Treatment includes antenatal steroids, exogenous surfactant, and respiratory support. Neonatal RDS is associated with high morbidity and mortality in preterm infants.
The larynx, also commonly called the voice box, is a cylindrical space located in the neck at the level of the C3–C6 vertebrae. The larynx is continuous superiorly with the oropharynx and inferiorly with the trachea. This structure is made up of 9 cartilages that are connected by membranes, ligaments, and muscles and that house the vocal cords. The major structures forming the framework of the larynx are the thyroid cartilage, cricoid cartilage, and epiglottis. The larynx serves to produce sound (phonation), conducts air to the trachea, and prevents large molecules from reaching the lungs.
Malignant lesions of the penis arise from the squamous epithelium of the glans, prepuce, or penile shaft. Penile cancer is rare in the United States, but there is a higher prevalence in lower socioeconomic regions. The most common histologic subtype is squamous cell carcinoma. Uncircumcised men and those with HPV infections are at highest risk of penile neoplasms. Diagnosis is a combination of physical exam, history, imaging studies, and tissue biopsy. Proper TNM staging is necessary to determine the correct treatment, which ranges from local topical therapy to multimodal surgery/radiation/chemotherapy.
Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Diffuse alveolar damage involves damage to the endothelial and alveolar epithelial cells and is associated with inflammation and the development of hyaline membranes lining the inner alveolar walls. The reparative stage follows after weeks, with fibrosis possibly occurring later. Clinically, the following triad of findings favors a diagnosis of ARDS: acute or rapidly progressive dyspnea, hypoxic respiratory failure (partial pressure of O2/fraction of inspired O2 ratio < 300 mm Hg), and bilateral alveolar opacities on chest imaging. Management involves determination and treatment of the cause while providing adequate oxygen, reducing further lung damage, and avoiding fluid overload. Most patients require mechanical ventilation. Acute respiratory distress syndrome is associated with high mortality or long-term complications potentially developing even after treatment.
The wrist connects the forearm to the hand. It consists of 8 carpal bones, multiple joints, and various supporting ligaments, as well as the distal bones of the forearm and the proximal portion of the 5 metacarpal bones of the hand. The wrist is crucial for the functioning of the upper limb, and it provides stability while positioning the hand for intricate motions.
Urinary tract infections (UTIs) represent a wide spectrum of diseases, from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Urinary tract infections are most commonly caused by Escherichia coli, but may also be caused by other bacteria and fungi. Depending on the location of the infection, patients can present with dysuria, urinary urgency, increased urinary frequency, suprapubic pain, and fever. Urinalysis and urine culture along with the clinical presentation help in the diagnosis of UTIs. Management options include oral or IV antibiotics such as trimethoprim-sulfamethoxazole, nitrofurantoin, and ceftriaxone. In certain instances, further workup may be needed to determine the underlying conditions that predispose an individual to UTIs.
Esophageal rupture or perforation is a transmural defect that occurs in the esophagus, exposing the mediastinum to GI content. The most common cause of esophageal perforation is iatrogenic trauma by instrumentation or surgical procedures. Perforation can also be due to foreign body ingestion or non-iatrogenic trauma produced by severe vomiting. Esophageal perforation presents with substernal chest pain that can have a sudden or insidious onset. Diagnosis can be achieved through a CT scan of the chest and neck, chest X-ray, or esophagogram. Management commonly includes surgical repair of the transmural esophageal defect. However, conservative therapy may also be considered for a hemodynamically stable patient with a minor defect. The main complication of esophageal perforation is acute mediastinitis. The mortality rate can range from 10%–50%.
Otitis externa (also known as external otitis or swimmer’s ear) is an infection of the external auditory canal that is most often caused by acute bacterial infection and is frequently associated with hot, humid weather and water exposure. Patients commonly present with ear pain, pruritus, discharge, and hearing loss. The diagnosis is made clinically. Most types of otitis externa are treated with topical antibiotic therapy. Complications include periauricular cellulitis and malignant otitis externa.
Computed tomography (CT) is one of the most commonly used imaging methods because it is widely available, fast, and reliable. CT scans deploy X-rays to obtain cross-sectional images of the body. A CT scanner consists of a tube that rotates around the patient and emits an X-ray beam and a detector that uses specialized software to receive and convert the beam to an image. The ability to create multiple views (axial, sagittal, coronal) and use contrast (intravenous, oral, rectal) allows for enhanced diagnostic yield. Patients are exposed to radiation, and special consideration should be given to patients with a history of iodine allergy, renal disease, or thyroid disease or patients who are pregnant.
Hyperkalemia is defined as a serum potassium (K+) concentration > 5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia is usually asymptomatic if minor in severity; however, acute elevations or severe hyperkalemia can lead to potentially fatal cardiac arrhythmias. Management is guided by severity and includes measures to stabilize the myocardial membrane potential, transiently shifting K+ intracellularly, removing K+ from the body, and treating the underlying predisposing conditions.
Vomiting, or emesis, is the forceful oral expulsion of gastric contents. Vomiting is a common presenting symptom in pediatrics. The frequency and characteristics of vomiting may point toward a specific pathology, just as its presence can be another symptom of a greater clinical situation. The majority of vomiting symptoms are benign and self-limited. A good history and physical examination can bring into focus the underlying cause and workup. Management is with antiemetics and treating the underlying cause, if needed. The most common complications are dehydration and malnutrition.
Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Patients typically present with shortness of breath initially during exercise and then at rest. Diagnosis may involve an echocardiogram, ECG, chest X-ray, pulmonary function tests, a ventilation-perfusion scan, laboratory testing for conditions associated with PAH, and/or cardiac catheterization. Management is often complex and aimed at treating the underlying etiology. Several classes of vasodilatory agents may be used for patients with primary PAH, including calcium channel blockers and vasoactive prostaglandins.
Nephrolithiasis is the formation of a stone, or calculus, anywhere along the urinary tract caused by precipitations of solutes in the urine. The most common type of kidney stone is the calcium oxalate stone, but other types include calcium phosphate, struvite (ammonium magnesium phosphate), uric acid, and cystine stones. Nephrolithiasis presents with colicky flank pain, which radiates to the groin, and hematuria due to damage to the ureters. Diagnosis is made by noncontrast CT of the abdomen and pelvis or by renal ultrasound, and urinalysis is performed to exclude concomitant urinary tract infection (UTI). Management depends on the size of the stone. Small stones likely to pass on their own are managed conservatively with hydration and analgesics. Large stones unlikely to pass spontaneously are managed with extracorporeal shock wave lithotripsy (ESWL), ureterorenoscopy, or percutaneous nephrolithotomy. Nephrolithiasis can be complicated by hydronephrosis or acute pyelonephritis. Adequate hydration is the best prophylactic intervention to prevent kidney stones.
Renal Na+ and water regulation work in tandem to control how fluid is distributed throughout the compartments of the body. Sodium is the body’s dominant extracellular solute, and is responsible for the osmotic force that keeps differing amounts of water in each compartment. Changes in Na+ balance are sensed by the body through changes in blood volume. Changes in water balance are sensed by the body through changes in plasma osmolality. Both ultimately send feedback signals to the kidneys to ensure that homeostasis is maintained. Abnormalities in these processes can result in problems in volume status (e.g., hypertension, pulmonary edema, pitting edema) and dysnatremias (hyponatremia and hypernatremia).
Pericardial effusion is the accumulation of excess fluid in the pericardial space around the heart. The pericardium does not easily expand; thus, rapid fluid accumulation leads to increased pressure around the heart. The increase in pressure restricts cardiac filling, resulting in decreased cardiac output and cardiac tamponade. Signs and symptoms usually occur in the setting of cardiac tamponade and include dyspnea, hypotension, muffled heart sounds, jugular venous distension, and pulsus paradoxus. The diagnosis of pericardial effusion is confirmed with echocardiography. Small effusions in stable patients are treated medically. Larger effusions and cardiac tamponade may require pericardiocentesis or pericardiotomy.
Acute abdomen, which is in many cases a surgical emergency, is the sudden onset of abdominal pain that may be caused by inflammation, infection, perforation, ischemia, or obstruction. The location of the pain, its characteristics, and associated symptoms (e.g., jaundice) are important tools that help narrow the differential diagnosis. Patients will typically have severe tenderness with associated rigidity and rebound tenderness. Laboratory evaluation will demonstrate leukocytosis, acidosis, and in some cases, abnormal hepatic function tests. Imaging helps narrow the differential diagnosis; first-line imaging is always an upright chest X-ray to evaluate for pneumoperitoneum. The treatment and prognosis of acute abdomen strongly depend on the underlying cause, but the vast majority of these cases constitute a surgical emergency with associated morbidity and mortality.
Coronary heart disease (CHD), or ischemic heart disease, describes a situation in which an inadequate supply of blood to the myocardium exists due to a stenosis of the coronary arteries, typically from atherosclerosis. The myocardium becomes ischemic when oxygen supply does not meet oxygen demand. Diagnosis is based on history and ECG findings; cardiac stress tests and catheterizations may also be needed. Treatment is primarily based on reducing the heart's oxygen demand and increasing the delivery of oxygen.
Wilms tumor is a malignancy caused by proliferation of metanephric blastema in the kidneys and is the most common renal malignancy in children. Wilms tumor usually arises sporadically, but it can also occur as a result of a specific congenital anomaly like WAGR (Wilms tumor, aniridia, genitourinary abnormalities, and mental retardation) syndrome, Denys–Drash syndrome, or Beckwith–Wiedemann syndrome. Wilms tumor commonly presents as a firm, nontender, smooth mass that does not cross the midline. Wilms tumor can also rarely present with abdominal pain, hematuria, and/or hypertension. The malignancy is diagnosed with abdominal ultrasonography and histopathologic studies (from biopsy or resection). Wilms tumor is treated with multimodal therapy (surgery, chemotherapy, radiation). Influenced by patient age, molecular markers, and pathologic findings, prognosis is favorable overall, with 5-year survival rates approaching 90%.
Myocarditis is an inflammatory disease of the myocardium, which may occur alone or in association with a systemic process. There are numerous etiologies of myocarditis, but all lead to inflammation and myocyte injury, most often leading to signs and symptoms of heart failure. The course of myocarditis may vary based on the etiology and timeline of symptom progression. The diagnosis is supported by clinical findings, laboratory evaluation, and cardiac imaging. A definitive diagnosis by endomyocardial biopsy is rarely required. Management is supportive and aimed at addressing complications.
Atherosclerosis is a common form of arterial disease in which lipid deposition forms a plaque in the blood vessel walls. Atherosclerosis is an incurable disease, for which there are clearly defined risk factors that often can be reduced through a change in lifestyle and behavior of the patient. It manifests itself as vessel stenosis and a source of thromboembolic disease. Its clinical manifestations depend on the specific vessels affected and include most notably coronary artery disease, carotid disease, and peripheral vascular disease. It is the most common primary disease of the arterial vascular system and is responsible for coronary heart disease, the leading cause of death worldwide.
Cardiomyopathy refers to a group of myocardial diseases associated with structural changes of the heart muscles (myocardium) and impaired systolic and/or diastolic function in the absence of other heart disorders (coronary artery disease, hypertension, valvular disease, and congenital heart disease). The list of causes is extensive, ranging from familial disorders to underlying diseases and infections. Patients often present with chest pain, dyspnea, palpitations, and/or syncope. Some patients may be completely asymptomatic, while others may present with sudden cardiac death as the first sign of an underlying condition. Diagnosis is made through the use of ECG and cardiac imaging such as echocardiography and cardiac MRI. Management involves medications typically used to treat heart failure, as well as implantable devices. In severe cases, heart transplantation may be necessary.
Hemolytic disease of the fetus and newborn (HDFN), also known as erythroblastosis fetalis, is caused by maternal IgG antibody destruction of the fetal RBCs. Rhesus (Rh) blood group incompatibility (frequently triggered by D antigen) and ABO incompatibility are common causes. In Rh incompatibility, an RhD-negative mother carries an RhD-positive baby; thus, antibodies form against antigens when fetal RBCs cross into the maternal circulation. In ABO incompatibility, commonly, a mother with blood type O has existing antibodies to A and B antigens. The affected baby can suffer from hemolytic anemia leading to severe neonatal jaundice, hydrops fetalis, cardiac complications, and fetal demise. If the pregnancy is affected by Rh incompatibility, antenatal surveillance is done to determine the need for intrauterine transfusion and early delivery. Postnatal treatment includes close monitoring, phototherapy for jaundice, and exchange transfusion in severe cases. For RhD-negative mothers, maternal sensitization can be prevented by using anti-D immunoglobulin (RhoGAM). Prognosis is excellent with prenatal care, blood type screening, and availability of RhD immune globulin.
Thyroid cancer is a malignancy arising from the thyroid gland cells: thyroid follicular cells (papillary, follicular, and anaplastic carcinomas) and calcitonin-producing C cells (medullary carcinomas). Rare cancers are derived from the lymphocytes (lymphoma) and/or stromal and vascular elements (sarcoma). Driver mutations involving the receptor tyrosine kinase pathway (such as RET and BRAF) and a family history of cancer or related syndromes increase the risk. Exposure to ionizing radiation and iodine deficiency are also considered risk factors. The major types can present as thyroid nodules or enlarged cervical lymph nodes. The diagnostic approach includes thyroid-stimulating hormone, ultrasonography, and biopsy. Treatment options are surgical removal of the thyroid gland, with the addition of radioactive iodine therapy and systemic therapy, depending on the type and extent of the thyroid malignancy.
Thyrotoxicosis refers to the classic physiologic manifestations of excess thyroid hormones and is not synonymous with hyperthyroidism, which is caused by sustained overproduction and release of T3 and/or T4. Graves’ disease is the most common cause of primary hyperthyroidism, followed by toxic multinodular goiter and toxic adenoma. Subacute thyroiditis is an example of thyrotoxicosis without hyperthyroidism, and a pituitary adenoma, which secretes thyroid-stimulating hormone (TSH) is an example of secondary hyperthyroidism. Clinical features of thyrotoxicosis are mostly due to an increase in the metabolic rate and overactivity of the sympathetic nervous system (i.e., an increase in the β-adrenergic “tone”). Thyrotoxicosis is diagnosed by measuring the levels of TSH produced by the anterior pituitary gland and unbound T4 and T3. Depending on the etiology and clinical presentation, it may be treated pharmacologically, surgically, or with radioiodine.
Multiple endocrine neoplasia syndromes are autosomal dominant inherited conditions characterized by 2 or more hormone-producing tumors involving the endocrine organs. There are different types of MEN, namely MEN1–4. The MEN1 syndrome is associated with MEN1 gene mutation and has a predilection for primary hyperparathyroidism, pituitary adenomas, and pancreatic tumors (the 3 P’s). Due to the RET proto-oncogene mutation, MEN2 syndrome can be further categorized as MEN2A and MEN2B. Medullary thyroid carcinoma and pheochromocytoma are common features. The MEN2A variant is associated with primary hyperparathyroidism, whereas MEN2B (also considered MEN3) is associated with neuromas and Marfanoid habitus. The newer and rare entity, MEN4, has features of MEN1 but results from CDKN1B mutations. The diagnosis is clinical, and tumors are detected based on imaging and correlating hormone levels. Genetic testing plays a crucial role in MEN2 syndromes in determining further management. Treatment is dependent on the tumors that are present and genetic mutation.
Crohn's disease is a chronic, recurrent condition that causes patchy transmural inflammation that can involve any part of the gastrointestinal tract. It is a type of inflammatory bowel disease (IBD) along with ulcerative colitis (UC). The terminal ileum and proximal colon are usually affected. Crohn's disease typically presents with intermittent, non-bloody diarrhea and crampy abdominal pain. Extraintestinal manifestations may include calcium oxalate renal stones, gallstones, erythema nodosum, and arthritis. Diagnosis is established via endoscopy with biopsy that shows transmural inflammation, characteristic “cobblestone” mucosa, and noncaseating granulomas. Management is with corticosteroids, azathioprine, antibiotics, and anti-TNF agents (infliximab and adalimumab). Complications include malabsorption, malnutrition, intestinal obstruction or fistula, and an increased risk of colon cancer.
Ulcerative colitis (UC) is an idiopathic inflammatory condition that involves the mucosal surface of the colon. It is a type of inflammatory bowel disease (IBD), along with Crohn's disease (CD). The rectum is always involved, and inflammation may extend proximally through the colon. Ulcerative colitis causes diffuse friability, erosions with bleeding, and loss of haustra, which are visible on endoscopy. Patients typically present with bloody diarrhea, colicky abdominal pain, tenesmus, and fecal urgency. Diagnosis is established via endoscopy with biopsy and by ruling out other causes of bloody diarrhea. Management is primarily through topical mesalamine, 6-mercaptopurine, or colectomy for severe cases. Complications include fulminant colitis, toxic megacolon, intestinal perforation, and increased risk of colorectal cancer.
Hypertrophic cardiomyopathy (HCM) is the most commonly inherited cardiomyopathy, which is characterized by an asymmetric increase in thickness (hypertrophy) of the left ventricular wall, diastolic dysfunction, and often left ventricular outflow tract obstruction. Hypertrophic cardiomyopathy is caused by various gene mutations affecting the contractile components of the heart, known as sarcomeres. Inheritance of HCM is typically autosomal dominant, although sporadic mutations also occur. Patients may be asymptomatic, present with dyspnea and chest pain or suffer sudden cardiac death without prior symptoms. Diagnosis is made based on ECG, echocardiography, stress test, and cardiac MRI. Symptomatic HCM is typically treated with beta-blockers as the 1st-line therapy. Additional management depends on the presence of left ventricular outflow tract obstruction.
Cardiac arrest is the sudden, complete cessation of cardiac output with hemodynamic collapse. Patients present as pulseless, unresponsive, and apneic. Rhythms associated with cardiac arrest are ventricular fibrillation/tachycardia, asystole, or pulseless electrical activity. The treatment of cardiac arrest begins with basic life support (BLS) when out-of-hospital and advanced cardiac life support (ACLS) when in-hospital. Basic life support comprises checking the patient’s mental status, activating the emergency response system, and cardiopulmonary resuscitation (CPR). An automated external defibrillator (AED) should be used once available. High-quality CPR (with early defibrillation in shockable rhythms) is crucial to survival in cardiac arrest. Advanced cardiac life support includes CPR, securing the airway, administering medications (such as epinephrine), and identifying and treatment of the cause of cardiac arrest. Post-cardiac arrest care follows return of spontaneous circulation (ROSC).
Heatstroke is an illness characterized as a core body temperature exceeding 40°C (104°F) with accompanying neurological symptoms including ataxia, seizures, and/or delirium. Heatstroke is usually due to the body’s inability to regulate its temperature when challenged with an elevated heat load. The illness can be classified as exertional or non-exertional. Management involves emergent stabilization, cooling, and supportive care. Early recognition and intervention are important to prevent complications or organ failure.
Hypothyroidism is a condition characterized by a deficiency of thyroid hormones. Iodine deficiency is the most common cause worldwide, but Hashimoto's disease (autoimmune thyroiditis) is the leading cause in non–iodine-deficient regions. Primary hypothyroidism occurs with thyroid gland disorders, while the central type arises from pituitary and hypothalamic conditions. Thyroid hormones are integral in metabolic processes and in the development of the brain and other organs. Congenital hypothyroidism can result in significant mental disability due to the loss of thyroid hormones. The features of acquired hypothyroidism also reflect the effects of slowed organ function, such as fatigue, bradycardia, cold intolerance, and exertional dyspnea. Diagnosis is by thyroid function testing. Elevated thyroid stimulating hormone and low free thyroxine (T4) levels are noted. Treatment is with synthetic T4.
Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Important clinical exam findings include a new or changed heart murmur and common extra-cardiac signs, such as Osler nodes, Janeway lesions, splinter hemorrhages, and Roth spots. The diagnosis is based on clinical findings, blood cultures, and echocardiography showing valvular vegetations. Management includes intravenous antibiotics for infectious cases, addressing the underlying etiology for noninfectious cases, and surgical repair when necessary.
The shoulder complex comprises the glenohumeral joint, sternoclavicular joint, acromioclavicular joint, and the scapulothoracic articulation, and connects the upper limb to the trunk. This group of joints consists of the clavicle, scapula, and humerus bones, multiple muscles and supporting ligaments, cartilage, and bursae. The muscles ensure the mobility and stability of the shoulder and upper limb and are divided into 3 groups: anterior axioappendicular, posterior axioappendicular, and scapulohumeral muscles.
Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Several conditions are associated with obesity, including diabetes, hypertension, and heart disease, all of which contribute to significant healthcare costs. Diagnosis is most commonly based on BMI measurement, wherein obesity is defined as BMI > 30. Management includes lifestyle changes, medications, or, in severe cases, bariatric surgery.
Necrotizing enterocolitis (NEC) is an intestinal inflammatory process that can lead to mucosal injury and necrosis. The condition is multifactorial, with underlying risk factors that include prematurity and formula feeding. The clinical presentation varies in severity from feeding intolerance, acute findings on abdominal exam, and systemic symptoms. The diagnosis is based on a clinical suspicion, abnormal abdominal radiographs, and supporting abnormal laboratory results. Management consists of supportive medical care for milder stages and bowel rest and surgical intervention for more advanced stages. Necrotizing enterocolitis and its complications carry a high risk of morbidity and mortality.
Condylomata acuminata are a clinical manifestation of genital HPV infection. Condylomata acuminata are described as raised, pearly, flesh-colored, papular, cauliflower-like lesions seen in the anogenital region that may cause itching, pain, or bleeding. Sexual contact is a common route of spread for HPV. While seen in all populations and ages, condylomata acuminata is most often seen in adolescence. HPV types 6 and 11 are responsible for 90% of warts and are considered low risk for malignancy; however, other types of HPV should be considered. Lesions rarely self-resolve; however, they can be removed via cryotherapy or topical antimitotic agents. While there is currently no treatment for HPV infection, it can be prevented through vaccination.
Primary amenorrhea is defined as the absence of menstruation in a girl by age 13 years in the absence of secondary sex characteristics or by the age of 15 years with the presence of secondary sex characteristics. Etiologies can originate in the hypothalamic–pituitary–ovarian (HPO) axis or from anatomic abnormalities in the uterus or vagina. Sometimes other endocrinopathies interfere with the sex hormones enough to suppress menstruation. Important factors to assess when working through the differential diagnosis are whether the patient has breast development (indicating exposure to estrogen from functional ovaries), the presence or absence of a uterus (indicating a potential genetic anomaly), and whether follicle-stimulating hormone (FSH) levels are high, low, or normal (providing insight into the HPO axis). Management includes correcting the underlying hormonal or anatomic issue, providing hormone replacement therapy (HRT), addressing fertility implications, and psychotherapy.
Prelabor rupture of membranes (PROM), previously known as premature rupture of membranes, refers to the rupture of the amniotic sac before the onset of labor. Prelabor rupture of membranes may occur in term or preterm pregnancies. The presentation includes a painless discharge of clear or pale-yellow fluid from the vagina in the form of a large gush or as small, intermittent trickles. Management depends on gestational age. Beyond 34 weeks, the recommendation is to induce labor and, if indicated, use antibiotics for group B streptococcus (GBS) prophylaxis. Prior to 34 weeks, management involves prolonging the pregnancy as long as possible while avoiding intra-amniotic infection (IAI), also known as chorioamnionitis, and minimizing risk to the fetus. The primary complications associated with PROM are related to infections and preterm birth.
Nephrotic syndrome is a renal disorder caused by conditions that increase the permeability of the glomerular filtration barriers. Nephrotic syndrome affects all age groups but has a higher pediatric prevalence. This disorder can be due to both primary (renal) and secondary (systemic) causes. Minimal change disease (MCD), is the most common presentation in children. Hallmark features include proteinuria of > 40 mg/m²/day, hypoalbuminemia, hypercholesterolemia, and edema. Diagnosis is based on history, physical exam, laboratory tests confirming nephrotic-range proteinuria and workup for systemic disease. Genetic testing is recommended in some cases. Steroids are the initial treatment in a classic presentation of the typically steroid-responsive MCD. In other cases, renal biopsy is indicated. Management and prognosis vary depending on the underlying cause and response to steroids.
Orbital and preseptal cellulitis are infections differentiated by the anatomic sites affected in the orbit. Infection anterior to the orbital septum is preseptal cellulitis; infection posterior to the septum is orbital cellulitis. Inoculation with the pathogen can occur through trauma or surgery. Cellulitis also occurs via extension from a nearby structure (such as from sinus infection or sinusitis). Patients will have eyelid erythema, pain, and swelling. Distinguishing characteristics of orbital cellulitis include ophthalmoplegia, proptosis, painful eye movement, and possible vision impairment. Complications are rare with preseptal cellulitis, and treatment can be initiated with oral antibiotics. Orbital cellulitis, however, requires intravenous broad-spectrum antibiotics and in severe cases, surgical drainage.
Haemophilus is a genus of Gram-negative coccobacilli, all of whose strains require at least 1 of 2 factors for growth (factor V [NAD] and factor X [heme]); therefore, it is most often isolated on chocolate agar, which can supply both factors. The most common pathogenic species is H. influenzae, which is transmitted through respiratory droplets and can cause epiglottitis, meningitis, otitis media, and pneumonia. H. ducreyi is transmitted through sexual contact and is the cause of chancroid, a type of genital ulcer.
Cushing's syndrome or hypercortisolism is a disorder characterized by features resulting from chronic exposure to excess glucocorticoids. Cushing's syndrome may be exogenous, due to chronic glucocorticoid intake, or endogenous, due to increased adrenal secretion of cortisol or adrenocorticotropic hormone (ACTH) production from the pituitary gland or ectopic sources. Exogenous or iatrogenic hypercortisolism is the most common cause. Typical clinical features of hypercortisolism include central obesity, thin and bruisable skin, abdominal striae, secondary hypertension, hyperglycemia, and proximal muscle weakness. The initial diagnostic approach is to establish hypercortisolism via urinary and salivary cortisol tests along with low-dose dexamethasone suppression test. Once the elevated cortisol levels are confirmed, the etiology is determined based on ACTH levels, confirmatory biochemical tests, and subsequent imaging studies. Treatment options depend on the cause, and include surgery and medical therapy.
Carcinoid tumors are small, well-differentiated, slow-growing neuroendocrine tumors (NET). Carcinoid syndrome describes the signs and symptoms associated with unregulated vasoactive hormone production by neuroendocrine tumors. Carcinoid tumors are most commonly found in the GI and bronchopulmonary tracts. Vasoactive substances produced by NET of the GI tract do not cause carcinoid syndrome until the tumors metastasize to the liver. Symptoms of carcinoid syndrome include flushing, diarrhea, and wheezing. Treatment consists primarily of surgical tumor resection and therapy with somatostatin analogs. Prognosis depends on the tumor location, aggressiveness, and overall disease burden.
Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. The pathophysiology involves the deposition of IgA immune complexes in multiple vessels following a trigger (infection/environmental), and the symptoms depend on the tissues that are involved. The diagnosis is established clinically, but can be supported with laboratory studies and skin or kidney biopsy. Management is mostly supportive, but may involve steroids and immunosuppressants in more severe cases. Prognosis is usually excellent, but some patients may develop end-stage renal failure.
Erectile dysfunction (ED) is defined as the inability to achieve or maintain a penile erection, resulting in difficulty to perform penetrative sexual intercourse. Local penile factors and systemic diseases, including diabetes, cardiac disease, and neurological disorders, can cause ED. Diagnosis is via physical exam and history. Management is guided by clearly discussing patient expectations after explaining the benefits and risks. Treatment includes conservative management with lifestyle modifications, oral medications, and injectables. Invasive surgical penile implants may be considered when conservative measures fail. Ultimately, both the patient and partner must be in tune with the treatment modalities to optimize their overall satisfaction.
Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of mental retardation. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Characteristic traits include upslanting, almond-shaped eyes with skin covering the inner aspects, broad flattened nasal bridge, small rounded ears, and small mouth with large tongue. Screening for Down syndrome occurs during the 1st and 2nd trimesters of pregnancy and includes both blood tests and prenatal ultrasonography. Ultimately, karyotyping confirms diagnosis in the prenatal or postnatal period. There is no cure for Down syndrome. Treatment is based on the clinical manifestations present; it includes a strong support system and early intervention programs to help with education and development.
Gonorrhea is a sexually transmitted infection (STI) caused by the gram-negative bacteria Neisseria gonorrhoeae (N. gonorrhoeae). Gonorrhea may be asymptomatic but commonly manifests as cervicitis or urethritis with less common presentations such as proctitis, conjunctivitis, or pharyngitis. Without antibiotic treatment, complications can occur. Complications for men may include epididymitis, prostatitis, balanitis, and periurethral abscess. Women may develop pelvic inflammatory disease, which can cause perihepatitis and fertility issues. Disseminated gonococcal infection is associated with fever, dermatitis, tenosynovitis, septic arthritis, and (rarely) endocarditis or meningitis. Gonorrhea diagnosis is made by microscopy, culture, or nucleic acid amplification tests. Management generally involves ceftriaxone, but treatment with doxycycline should be pursued if a coinfection with Chlamydia trachomatis (C. trachomatis) is not excluded.
Abnormal uterine bleeding is the medical term for abnormalities in the frequency, volume, duration, and regularity of the menstrual cycle. Abnormal uterine bleeding is classified using the acronym PALM-COEIN, with PALM representing the structural causes and COEIN indicating the non-structural causes. Etiologies include polyp (P), adenomyosis (A), leiomyoma (L), malignancy/hyperplasia (M), coagulopathy (C), ovulatory dysfunction (O); endometrial pathology including endometritis and atrophy (E), iatrogenic causes (I), and etiologies not otherwise classified (N). Diagnosis usually requires careful history-taking and examination, basic laboratory work, transvaginal ultrasound, and endometrial biopsy based on age and risk factors. Management depends on the underlying etiology, but often includes oral contraceptive pills, levonorgestrel-containing intrauterine devices, and surgery.
Syphilis is a bacterial infection caused by the spirochete Treponema pallidum pallidum (T. p. pallidum), which is usually spread through sexual contact. Syphilis has 4 clinical stages: primary, secondary, latent, and tertiary. Primary syphilis begins with a chancre, a painless ulcer on the genitals. Progression to secondary syphilis manifests as a generalized maculopapular rash, which includes the palms and soles. The development of tertiary syphilis can cause severe neurologic (neurosyphilis), cardiovascular, and/or gummatous disease. The diagnosis is through both treponemal and nontreponemal testing. Penicillin G is the antibiotic of choice. The duration of management varies based on the stage of the disease.
Alcoholic liver disease is a spectrum of disorders ranging from fatty liver to cirrhosis secondary to chronic alcohol abuse. Excessive and prolonged consumption of alcohol results in impairment of the lipolysis pathway, causing inflammatory changes within the hepatocytes. Patients typically present during the hepatitis stage with jaundice, fever, and abdominal pain. Diagnosis is based on a history of alcohol abuse and confirmed by laboratory derangement with an AST/ALT ratio > 2. Alcoholic liver disease carries a high mortality rate if patients present with severe hepatitis. Management aims at alcohol abstinence for reversal (at certain stages) and addressing contributing factors (such as viral infections or drugs) to minimize damage to the hepatocytes. Approximately 10% of patients regress with alcohol abstinence during the hepatitis stage. Cirrhosis is frequently irreversible.
Menopause is a physiologic process in women characterized by the permanent cessation of menstruation that occurs after the loss of ovarian activity. Menopause can only be diagnosed retrospectively, after 12 months without menstrual bleeding. During the menopausal transition, reproductive hormones can fluctuate significantly, leading to symptoms that include hot flushes, sleep and mood disturbances, and vaginal dryness. In postmenopausal woman, low estrogen levels contribute to an increased risk for cardiovascular disease, osteoporosis, and sexual dysfunction due to vulvovaginal atrophy. For some women, symptoms negatively affect their quality of life and treatment is warranted. Management usually involves hormone replacement therapy (HRT), but other treatment options also exist.
Osteoporosis refers to a decrease in bone mass and density leading to an increased number of fractures. There are 2 forms of osteoporosis: primary, which is commonly postmenopausal or senile; and secondary, which is a manifestation of immobilization, underlying medical disorders, or long-term use of certain medications. Osteoporosis most often presents clinically with frequent fractures and loss of vertebral height. Diagnosis is established by measuring bone mineral density. Management includes lifestyle modifications, maintaining adequate levels of calcium and vitamin D, and the use of bisphosphonates.
Intestinal malrotation is a congenital anomaly that results from failure of the GI tract to undergo normal rotation around the mesenteric vessels during embryologic development. This condition can result in several anatomic patterns characterized by abnormal location and attachments of the abdominal cavity's intestines. These anomalies can be clinically silent or present with a number of complications, the most catastrophic of which is midgut volvulus. Intestinal malrotation usually presents in infancy as an acute onset of bilious vomiting. Definitive diagnosis is established with the upper GI series and the treatment is emergent surgery.
Primary ovarian insufficiency (POI) is a condition resulting from the depletion or dysfunction of the ovarian follicles, leading to cessation of ovulation and menses before age 40. Primary ovarian insufficiency is primarily idiopathic, but it can also be seen in association with chromosomal and genetic defects, including Turner syndrome (45,X karyotype) and FMR1 premutation. Patients present with signs and symptoms of menopause prior to age 40, including oligomenorrhea or amenorrhea, vaginal dryness (often leading to dyspareunia), and infertility. Key laboratory findings include elevated follicle-stimulating hormone (FSH) and low estrogen levels. Once the diagnosis of POI is made, the patient should be screened for autoimmune adrenal antibodies, and a karyotype, FMR1 premutation screen, and baseline DEXA scan should be obtained. Management includes hormone replacement therapy (HRT), addressing fertility concerns as desired, and psychological support.
Pheochromocytoma is a catecholamine-secreting tumor derived from chromaffin cells. The majority of tumors originate in the adrenal medulla, but they may also arise from sympathetic ganglia (also referred to as paraganglioma). Symptoms are associated with excessive catecholamine production and commonly include hypertension, tachycardia, headache, and sweating. Pheochromocytomas are frequently familial and associated with genetic syndromes. Approximately 90% of pheochromocytomas are benign and surgical resection is the only curative treatment. Prognosis is generally good for benign, sporadic tumors that have been completely resected. Familial forms are associated with higher recurrence rates and malignant potential.
Truncus arteriosus (TA) is a congenital heart defect characterized by the persistence of a common cardiac arterial trunk tract that fails to divide into the pulmonary artery and aorta during embryonal development. Truncus arteriosus is a rare congenital malformation with a high mortality rate within the 1st 5 weeks of life if not managed promptly. Neonates may be asymptomatic at birth but invariably develop respiratory distress and heart failure. Diagnosis is commonly made prenatally through screening ultrasounds. In the event of a missed antenatal diagnosis, TA is confirmed through an echocardiogram. Treatment involves medical stabilization immediately after birth, followed by definitive surgery. With appropriately timed management, the prognosis is excellent.
Coarctation of the aorta is a narrowing of the aorta between the aortic arch and the iliac bifurcation commonly around the point of insertion of the ductus arteriosus. Coarctation of the aorta is typically congenital and the clinical presentation depends on the age of the patient. Neonates present with heart failure upon the closure of the ductus arteriosus, while children and adults present with hypoperfusion and/or hypertension. Classic findings on physical exam include radio-/brachio-femoral delay and decreased blood pressure in the lower limbs. Diagnosis is confirmed by echocardiogram. Patients should be surgically managed as early as possible to avoid complications of hypertension. Close follow-up is required as the risk of hypertension and re-coarctation remain.
Benign or nonacute scrotal masses are represented by hydroceles, varicoceles, and spermatoceles. Key components to evaluation are physical exam and scrotal ultrasound. Hydroceles represent extra fluid in the tunica vaginalis, leading to a swollen scrotum. Varicoceles have a dilatation of the pampiniform venous plexus, giving the “bag of worms” appearance on exam. Spermatoceles present as an epididymal cyst, commonly arising from the head of the epididymis. Hydroceles, varicoceles, and spermatoceles are usually asymptomatic and do not require treatment unless they are causing pain or other complications.
Cervical cancer, or invasive cervical carcinoma (ICC), is the 3rd most common cancer in women in the world, with > 50% of the cases being fatal. In the United States, ICC is the 13th most common cancer and the cause of < 3% of all cancer deaths due to the slow progression of precursor lesions and, more importantly, effective cancer screening. There are 2 major histologic types of ICC: squamous cell carcinoma (SCC) and adenocarcinoma. High-risk human papillomaviruses (hrHPVs) cause > 99% of SCCs and > 85% of adenocarcinomas. Early cervical neoplasia is asymptomatic, and diagnosis is made using routine screening methods, including the cervical Papanicolaou test with cytology, hrHPV testing, and biopsy. Treatment of precursor or dysplastic lesions depends on the severity of the dysplasia and the age of the patient. Management of ICCs depends on the stage and varies from excisional biopsy by cervical cone biopsy for microinvasive ICC to radical hysterectomy for more advanced cases. If there is extracervical spread, radiation and chemotherapy would be recommended.
Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. The clinical presentation can vary greatly. Notable clinical features include malar rash, nondestructive arthritis, lupus nephritis, serositis, cytopenia, thromboembolic disease, seizures, and/or psychosis. Diagnosis is based on clinical criteria, and includes tests to determine ANAs, SLE-specific antibodies, and specific clinical findings. The goal of management is to control symptoms and prevent organ damage, using corticosteroids, hydroxychloroquine, and immunosuppressants.
Intussusception occurs when a part of the intestine (intussusceptum) telescopes into another part (intussuscipiens) of the intestine. The condition can cause obstruction and, if untreated, progress to bowel ischemia. Intussusception is most common in the pediatric population, but is occasionally encountered in adults. The pediatric patient typically presents with acute cyclical abdominal pain and vomiting, while adults present with symptoms of bowel obstruction. The diagnosis in children is frequently clinical but may be supported by an abdominal ultrasound showing a classic target sign. Management options in children include contrast or pneumatic enema, with surgical options reserved for failure of the non-operative measures, complications such as gangrene or perforation, and treatment of underlying pathology. In adult patients, surgery is usually required.
Pelvic inflammatory disease (PID) is defined as a polymicrobial infection of the upper female reproductive system. The disease can affect the uterus, fallopian tubes, ovaries, and adjacent structures. Pelvic inflammatory disease is closely linked with sexually transmitted diseases, most commonly caused by Chlamydia trachomatis and Neisseria gonorrhoeae, as well as organisms associated with bacterial vaginosis, such as Gardnerella vaginalis. Common symptoms are lower abdominal pain, cervical discharge, and irregular vaginal bleeding. Complications of PID can include ectopic pregnancy, chronic pelvic pain, and infertility. Diagnosis is primarily clinical in addition to PCR testing of cervical specimens and sometimes imaging or laparoscopy. Due to its polymicrobial nature, PID treatment is with combination antibiotic regimens.
Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Molecular profiling of the cancer provides further distinction of the tumor's biological behavior, prognosis, and treatment options. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Regional and metastatic spread cause additional symptoms and complications depending on the location and organ(s) affected. Related paraneoplastic syndromes include hypercalcemia, hyponatremia, Lambert-Eaton syndrome, Cushing's syndrome, polydermatomyositis, and dermatomyositis. Definitive diagnosis and staging are made by biopsy, genetic mutation with biomarker testing, and imaging. Management is guided by the cancer stage and associated molecular profile. Lung cancer carries an overall poor prognosis.
Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Deep vein thrombosis (DVT) is diagnosed in > 50% of patients presenting with symptoms, in whom the lower-extremity deep-venous system is the most common source of thrombus. Some individuals are asymptomatic, but the most common presenting symptom is dyspnea. The symptoms can be acute or chronic, and diagnosis is usually based on radiographic findings. Initial management is supportive and focuses on restoring oxygenation and hemodynamic stability. Both medical (systemic anticoagulants) and interventional therapies (catheter-based approach, surgery) are used to reestablish vessel patency.
Hemorrhoids are normal vascular cushions in the anal canal composed of dilated vascular tissue, smooth muscle, and connective tissue. They do not cause issues unless they are enlarged, inflamed, thrombosed, or prolapsed. Patients often present with rectal bleeding of bright red blood, or they may have pain, perianal pruritus, or a palpable mass. Risk factors include family history, low-fiber diet, and constipation. The two main types of hemorrhoids are external, usually with perianal pain, and internal, which are usually painless. The main diagnostic tools are history, physical exam, and endoscopic procedures if indicated for further investigation. If symptoms are acute, excision can be performed for external hemorrhoids. Otherwise, conservative management is recommended. Surgical methods are reserved for more severe hemorrhoids or those unresponsive to primary treatment.
Whipple's disease is a rare malabsorption syndrome with systemic manifestations (neurologic, cardiac, and musculoskeletal) caused by the bacterium Tropheryma whipplei. Patients often present with weight loss, diarrhea/steatorrhea, and arthralgias, as well as neurologic and cardiac manifestations. Whipple's disease is diagnosed with biopsy after the visualization of periodic acid–Schiff (PAS)-positive foamy macrophages in the involved tissues or with PCR for the bacterial DNA. It is managed with antibiotics, namely ceftriaxone or penicillin G and sulfamethoxazole.
Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Associated symptoms, including fever, nausea and vomiting, weight loss, and bloody stools are also important to elicit from the history. Most causes of acute diarrhea are infectious and do not require additional workup. Since diarrhea is usually a self-limited condition, management is generally supportive. However, chronic diarrhea can require laboratory studies, stool studies, imaging, or procedures to determine the cause. Management ultimately hinges on treating the underlying pathology, though symptomatic and empiric therapies may be utilized under the right circumstances.
Fibrocystic change of the breast is a non-specific term referring to several types of benign breast conditions. These are non-proliferative lesions, which include cystic and fibrous tissue formation. Fibrocystic changes are seen in up to 50–60% of women, most commonly between 30–50 years of age. Changes are stimulated by both estrogen and progesterone, and often diminish or resolve with menopause. Patients typically present with a breast mass, “lumpy” or firm breasts, and/or cyclic breast pain. The work-up involves imaging, with mammogram or ultrasound, and biopsy (if needed) to exclude malignancy. Management includes observation, supportive measures, and altering hormone therapy, as needed. These changes do not appear to significantly increase the risk for breast cancer.
Androgen insensitivity syndrome (AIS) is an X-linked recessive condition in which a genetic mutation affects the function of androgen receptors, resulting in complete (CAIS), partial (PAIS), or mild (MAIS) resistance to testosterone. All individuals with AIS have a 46,XY karyotype; however, phenotypes vary and include phenotypic female, virilized female, undervirilized male, and phenotypic male individuals. Androgen insensitivity syndrome always leads to infertility. Hormone analysis, imaging, and genetic testing help make the diagnosis. Management of AIS varies depending on the degree of androgen sensitivity, phenotype, and gender identity, and may involve hormone-replacement therapy and surgery to correct anatomical anomalies of the reproductive and genital structures.
Ventricular septal defects (VSDs) are congenital cardiac malformations that feature an abnormal communication between the right and left ventricles. Presenting both in isolation or as part of a more complex disease, VSD is the most common congenital heart defect. While the degree of severity depends on the size of the defect, VSDs are classified on the basis of the anatomical location of the defect. Patients may be asymptomatic with smaller defects, whereas larger defects can present with respiratory or heart failure during infancy or childhood. A common clinical sign is a holosystolic murmur audible at the left sternal border. Diagnosis, both pre- and post-natal, is confirmed by echocardiogram. The majority of small VSDs close spontaneously, but those that are larger and symptomatic require medical stabilization followed by surgical repair.
Testicular torsion is the sudden rotation of the testicle, specifically the spermatic cord, around its axis in the inguinal canal or below. The acute rotation results in compromised blood flow to and from the testicle, which puts the testicle at risk for necrosis. Quick diagnosis and intervention is key to saving the affected testicle. Emergent surgical exploration with subsequent orchidopexy is required. Ultrasound or manual detorsion should not delay definitive care.
Prostatitis is inflammation or an irritative condition of the prostate that presents as different syndromes: acute bacterial, chronic bacterial, chronic prostatitis/chronic pelvic pain, and asymptomatic. Bacterial prostatitis is easier to identify clinically and the management (antibiotics) is better established. Whether the condition is in an acute or chronic state determines the length of antibiotic treatment. The main diagnostic tools are history, physical examination, and work-up investigating the sources of infection (urinalysis and culture). Digital rectal examination is only recommended in patients with chronic prostatitis and not in acute bacterial prostatitis due to the risk of sepsis. Chronic pelvic pain syndrome is a diagnosis of exclusion and requires multimodal pain management with established patient expectations. The asymptomatic type is an incidental finding that is recognized when a patient has other urologic issues.
Rheumatoid arthritis (RA) is a symmetric, inflammatory polyarthritis and chronic, progressive, autoimmune disorder. Presentation occurs most commonly in middle-aged women with joint swelling, pain, and morning stiffness (often in the hands). Systemic inflammation can lead to extraarticular manifestations such as rheumatoid nodules, interstitial lung disease, Felty syndrome, and pericarditis. Prolonged and severe disease can lead to irreversible joint deformities. Diagnosis is based on strong clinical suspicion and confirmed by the presence of rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibodies, and characteristic imaging. Management involves long-term disease-modifying antirheumatic drugs (DMARDs), biologic agents, and physical therapy. Glucocorticoids and nonsteroidal antiinflammatory drugs (NSAIDs) are the treatment of choice for acute exacerbation.
Melanoma is a malignant tumor arising from melanocytes, the melanin-producing cells of the epidermis. These tumors are most common in fair-skinned individuals with a history of excessive sun exposure and sunburns. Melanomas usually present as pigmented skin lesions, but they can occur on mucosal surfaces, such as in the eyes, anal canal, and genital regions. Common findings may include Asymmetry of the lesion, irregular Border, varying Color, > 6 mm Diameter, and Evolving features (ABCDE). Definitive diagnosis is established with biopsy. Treatment relies primarily on surgical excision. The prognosis is very good for early-stage lesions but quite dismal for metastatic disease. Of all the skin malignancies, melanoma generally carries the worst prognosis.
An important complication of anesthesia is malignant hyperthermia, an autosomal dominant disorder of the regulation of calcium transport in the skeletal muscles resulting in a hypermetabolic crisis. Malignant hyperthermia is marked by high fever, muscle rigidity, rhabdomyolysis, and respiratory and metabolic acidosis. The mortality rate reaches 90% if not quickly identified and treated. Management involves stopping the offending agent and administering dantrolene.
Congenital adrenal hyperplasia (CAH) consists of a group of autosomal recessive disorders that cause a deficiency of an enzyme needed in cortisol, aldosterone, and androgen synthesis. The most common subform of CAH is 21-hydroxylase deficiency, followed by 11β-hydroxylase deficiency. Clinical manifestations depend on the specific enzyme affected. Notably, CAH is the most common cause of ambiguous genitalia in genotypic female individuals. All forms of CAH cause low levels of cortisol, high levels of adrenocorticotropic hormone (ACTH), and adrenal hyperplasia. Laboratory studies help confirm the diagnosis. Lifelong glucocorticoid replacement is needed, and surgical correction of ambiguous genitalia is often performed.
Epididymitis and orchitis are characterized by acute inflammation of the epididymis and the testicle, respectively, due to viral or bacterial infections. Patients typically present with gradually worsening testicular pain and scrotal swelling along with systemic symptoms such as fever, depending on severity. Patients with concomitant sexually transmitted diseases (STDs) may present with lower urinary tract symptoms. Diagnosis is based on clinical findings and urinalysis with culture. Scrotal ultrasound may show increased blood flow to the affected epididymis or testicle. Treatment is with empiric gram-negative coverage antibiotics and culture-directed therapy. Supportive care includes scrotal support and non-steroidal anti-inflammatory drugs.
The ductus arteriosus (DA) is a fetal blood vessel connecting the left pulmonary artery to the aorta. The DA allows blood to bypass pulmonary circulation. After birth, the DA remains open for up to 72 hours and then constricts and involutes, becoming the ligamentum arteriosum. Failure of this process to occur results in patent ductus arteriosus (PDA), a condition that causes up to 10% of congenital heart defects. Patent ductus arteriosus is twice as common in girls (especially premature infants) and causes a continuous machinery-like murmur on clinical examination. Patent ductus arteriosus may be associated with other cardiac defects; an echocardiogram can confirm the diagnosis. Treatment aims at closure of the remnant structure either through pharmacological or surgical means.
Mastitis is inflammation of the breast tissue with or without infection. The most common form of mastitis is associated with lactation in the first few weeks after birth. Non-lactational mastitis includes periductal mastitis and idiopathic granulomatous mastitis (IGM). Lactational mastitis is most commonly caused by Staphylococcus aureus that is introduced into the breast milk during breastfeeding. The etiology of non-lactational mastitis is poorly understood, but periductal mastitis is commonly associated with smoking, and IGM is frequently associated with Corynebacterium. Patients present with edema, erythema, tenderness, and, possibly, a mass in the breast. Diagnosis is usually clinical, although ultrasound, cultures, and biopsy may be required in some cases. Management involves antibiotics, analgesics, drainage of any abscesses, and surgical duct excision for periductal mastitis.
Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder of reproductive-age women, affecting nearly 5%‒10% of women in the age group. Characterized by hyperandrogenism, chronic anovulation leading to oligomenorrhea (or amenorrhea), and metabolic dysfunction, PCOS increases a woman’s risk for infertility, endometrial hyperplasia or carcinoma, and cardiovascular disease. The pathophysiology is incompletely understood but thought to have a multifactorial genetic basis causing altered pulsatile release of gonadotropin-releasing hormone (GnRH), as well as increases in luteinizing hormone (LH), androgens, estrogen, and insulin: The result is chronic anovulation and hirsutism, which define the condition. Diagnosis is one of exclusion; therefore, other causes of abnormal uterine bleeding and hirsutism must be ruled out. Management includes attempting to restore normal ovulation through weight loss, oral contraceptive pills (OCPs), and fertility assistance.
Mesenteric ischemia is a rare, life-threatening condition caused by inadequate blood flow through the mesenteric vessels, which results in ischemia and necrosis of the intestinal wall. Mesenteric ischemia can be either acute or chronic. Acute mesenteric ischemia may be caused by an arterial embolism, thrombosis, non-occlusive disease, or venous thrombosis. Chronic mesenteric ischemia is most commonly caused by atherosclerotic disease. Patients present with abdominal pain out of proportion to the abdominal examination. Peritonitis, sepsis, and hematochezia are concerning for bowel infarction. Computed tomography (CT) with angiography of the abdomen and pelvis is the diagnostic modality of choice. Management is often surgical and focuses on re-establishing blood flow to the intestines, as well as resection of any nonviable bowel.
A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Management is greatly dependent on the extent of surface area affected and the depth of the burns. Management involves fluid resuscitation, adequate analgesia, and appropriate wound care with the goal of preventing opportunistic infection.
Breast cancer is the most common cancer in women and the 2nd-leading cause of cancer-related deaths in women in the United States. Early detection and improved pathology-specific treatments have resulted in a decrease in death rates. Several organizations provide recommendations regarding screening for specific age and risk groups. Screenings include breast examination, mammography, magnetic resonance imaging (MRI), and ultrasound (US).
The term vulvovaginitis is used to describe an acute inflammation of the vulva and vagina. Vulvovaginitis can be caused by several infectious and non-infectious etiologies, and results from disruption of the normal vaginal environment. Common signs and symptoms include pain, pruritis, erythema, and edema of the affected region, as well as vaginal discharge and dyspareunia. The diagnosis is based on the clinical presentation, physical examination findings, and inspection of vaginal secretions. Management depends on the etiology, including antimicrobials for infectious causes.
Lung cancer is the leading cause of cancer-related death in the United States, with 90% of cases being fatal. The vast majority of cases are associated with smoking, and thus smoking cessation is encouraged to reduce a patient’s lifetime risk. Annual screening with low-dose computed tomography is recommended for early detection in patients 50–80 years of age with a significant smoking history. This screening program has been shown to significantly reduce mortality.
Hypoplastic left heart syndrome (HLHS) is a congenital heart defect that consists of the underdevelopment, or hypoplasia, of the left side of the heart in various degrees. The most notable feature of HLHS is the reduced size and functionality of the left ventricle (LV). Also, HLHS is associated with stenosis, hypoplasia, or atresia of the vessels or atrioventricular valves on the left side of the heart. A mixture of genetic factors and altered fetal blood flow causes HLHS. Hypoplastic left heart syndrome presents once the ductus arteriosus closes physiologically as tachypnea, cyanosis, heart failure, and cardiogenic shock. Diagnosis can be made pre- or postnatally via echocardiogram. Once detected, surgical treatment is the 1st-line therapy, done in 3 stages.
A hemothorax is a collection of blood in the pleural cavity. Hemothorax most commonly occurs due to damage to the intercostal arteries or from a lung laceration following chest trauma. Hemothorax can also occur as a complication of disease, or hemothorax may be spontaneous or iatrogenic. Large hemothoraces can be life-threatening by leading to lung collapse. Patients present with shortness of breath and chest pain. Physical exam findings include hypotension, tachycardia, decreased lung sounds, and dullness on percussion of the chest. Diagnosis is by upright chest X-ray. Management is with tube thoracostomy drainage, video-assisted thoracoscopic surgery (VATS), or thoracotomy when massive hemothorax or persistent bleeding is present.
Blunt chest trauma is a non-penetrating traumatic injury to the thoracic cavity. Thoracic traumatic injuries are classified according to the mechanism of injury as blunt or penetrating injuries. Different structures can be injured including the chest wall (ribs, sternum), lungs, heart, major blood vessels, and the esophagus. The extent and specific type of thoracic traumatic injury can be identified by a proper history and physical examination supported by adequate imaging studies. Management depends on the specific type of injury.
Treponema is a gram-negative, microaerophilic spirochete. Owing to its very thin structure, it is not easily seen on Gram stain, but can be visualized using dark-field microscopy. This spirochete contains endoflagella, which allow for a characteristic corkscrew movement. The bacteria are able to avoid immune recognition and phagocytosis by forming a protective coating with fibronectin. Humans are the only reservoir and transmission is through human-to-human contact. The most common species involved in human disease is Treponema pallidum subspecies pallidum, which is the causative agent of syphilis. Other clinically relevant species include T. pallidum pertenue, T. pallidum endemicum, and T. carateum. These are the causative organisms for yaws, bejel, and pinta, respectively.
Cryptorchidism is one of the most common congenital anomalies in young boys. Typically, this asymptomatic condition presents during a routine well-child examination where 1 or both testicles are not palpable in the scrotum. Diagnosis depends on physical exam and ultrasound is performed only when other disorders are suspected. Treatment is dependent on patient age and testis position. In boys with persistent undescended testis by age 6 months, the condition is unlikely to spontaneously resolve. If the testis is palpable but not in the dependent intrascrotal location, an orchiopexy (bringing the testicle to the scrotum) is preferred. If the testis is non-palpable, a diagnostic laparoscopy is needed to inspect for an intra-abdominal testis, which requires a staged Fowler-Stephen’s orchiopexy.
Chlamydiae are obligate intracellular gram-negative bacteria. They lack a peptidoglycan layer and are best visualized using Giemsa stain. Chlamydiae species have a complex replication cycle consisting of 2 morphological forms: elementary bodies and reticulate bodies. The family of Chlamydiaceae comprises 3 pathogens that can infect humans: Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae. Sometimes, C. psittaci and C. pneumoniae are classified as a separate genus, Chlamydophila. C. trachomatis is the most common bacterium responsible for causing sexually transmitted diseases in the United States and is associated with urogenital infections, lymphogranuloma venereum, neonatal conjunctivitis, and trachoma. C. psittaci causes psittacosis (parrot fever), whereas C. pneumoniae causes atypical pneumonia.
Endometriosis is a common disease in which patients have endometrial tissue implanted outside of the uterus. Endometrial implants can occur anywhere in the pelvis, including the ovaries, the broad and uterosacral ligaments, the pelvic peritoneum, and the urinary and gastrointestinal tracts. Implants outside of the abdominopelvic cavity are also possible, though uncommon. Endometriosis typically presents in a reproductive-aged female with pelvic pain that worsens around menstruation. Endometrial implants tend to be inflammatory, leading to cyclic, chronic pain; adhesions; and an increased risk of infertility. The diagnosis is usually made clinically, though definitive diagnosis requires laparoscopy. Lab work is rarely useful. Management involves suppression of endometrial growth with progestins, typically with oral contraceptive pills. In severe cases, surgery is helpful to confirm the diagnosis and treat any implants.
Human immunodeficiency virus (HIV) infection is a sexually transmitted or blood-borne infection that destroys CD4 T cells. Chronic HIV infection and depletion of CD4 cells eventually results in acquired immunodeficiency syndrome (AIDS), which can be diagnosed by the presence of certain opportunistic diseases called AIDS-defining conditions. These conditions include a wide spectrum of bacterial, viral, fungal, and parasitic infections as well as several malignancies and generalized conditions. These serious and life-threatening diseases are generally not seen in immunocompetent patients. Treatment of HIV is very important in managing these diseases, and the incidence of AIDS-defining conditions has declined with the use of antiretroviral therapy.
Human immunodeficiency virus (HIV), a single-stranded RNA virus belonging to the Retroviridae family, is the etiologic agent of acquired immunodeficiency syndrome (AIDS). The human immunodeficiency virus is a sexually transmitted or blood-borne infection that attacks CD4+ T lymphocyte cells, macrophages, and dendritic cells, leading to eventual immunodeficiency. The presentation is marked by constitutional symptoms such as lymphadenopathy and fever. Further progression predisposes to opportunistic infections and malignancies. Diagnosis is by enzyme immunoassay for HIV-1 and -2. Additional tests include HIV viral load, genotyping, and CD4+ T lymphocyte count to determine therapy and evaluate treatment response and disease progression. Immediate treatment with combination antiretroviral therapy is recommended.
Aortic dissection occurs due to shearing stress from pulsatile pressure causing a tear in the tunica intima of the aortic wall. This tear allows blood to flow into the media, creating a “false lumen.” Aortic dissection is most commonly caused by uncontrolled hypertension. Complications arise due to partial occlusion of vital branches off the aorta and reduced blood flow to the brain, visceral organs, and extremities. Patients often present with acute, tearing chest or back pain. Computed tomography is the diagnostic modality of choice. All type A dissections (ascending aorta) are a surgical emergency due to the risk of imminent rupture. Type B dissections (descending aorta) can be managed medically with impulse control using beta-blockers and calcium channel blockers. If there is evidence of malperfusion to visceral organs or extremities, aneurysm dilation to > 5 cm, retrograde extension into the ascending aorta, or intractable pain, the patient will need evaluation for endovascular or open repair.
Legg-Calvé-Perthes disease (LCPD) is characterized by idiopathic avascular necrosis of the femoral head. The disease presents as a limp with an insidious onset and associated hip pain. Legg-Calvé-Perthes disease primarily affects school-age children and has a male predominance. The exact mechanism of this disease is unknown and the diagnosis is made by clinical findings and imaging. Management can be conservative or surgical, depending on severity and the age of the patient.
Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Genetic factors, age, and hormonal and environmental influence contribute to the progression of the disease. The most common histologic type is infiltrating ductal carcinoma, which is > 75% of all breast cancers. Screening mammography is recommended for early disease detection. Diagnosis is by core needle biopsy, with biologic factors determined by immunohistochemical testing. Surgery, systemic treatment (chemotherapy, biologic therapy, endocrine therapy), and radiation therapy (RT) are part of the early-stage and locally advanced disease management. In metastatic breast cancer, systemic treatment is utilized with palliative measures.
The hip joint is a ball-and-socket joint formed by the head of the femur and the acetabulum of the pelvis. The hip joint is the most stable joint in the body and is supported by a very strong capsule and several ligaments, allowing the joint to sustain forces that can be multiple times the total body weight. Tolerating these forces is possible thanks to the bony alignment and substantial support from the static and dynamic stabilizers of the hip. Several muscle groups attach to the components of the hip joint, allowing for the joint's range of motion. The muscles that attach to the hip joint include those of the gluteal region and thigh.
Hypothermia can be defined as a drop in the core body temperature below 35°C (95°F) and is classified into mild, moderate, severe, and profound forms based on the degree of temperature decrease. Certain populations may be more vulnerable to accidental hypothermia, including extremes of age, homeless, mentally ill, and alcohol and drug abusers. Evaluation should include assessment for associated trauma and contributing medical conditions. Management involves rewarming the patient by different methods based on the severity of the hypothermia.
Osteoarthritis (OA) is the most common form of arthritis, and is due to cartilage destruction and changes of the subchondral bone. The risk of developing this disorder increases with age, obesity, and repetitive joint use or trauma. Patients develop gradual joint pain, stiffness lasting < 30 minutes, and decreased range of motion. Physical exam may reveal crepitus with joint motion and osteophyte formation (Heberden's and Bouchard's nodes). The diagnosis is clinical and supported with radiographic joint findings. Management includes conservative measures, analgesic medications, glucocorticoid intra-articular injections, and surgery for advanced disease.
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a disorder of impaired water excretion due to the inability to suppress the secretion of antidiuretic hormone (ADH). The inappropriate secretion of ADH can be due to various causes, including increased production by the pituitary gland due to trauma, disease, or certain medications; the ectopic secretion of ADH by cancer; or hereditary causes (nephrogenic SIADH). Syndrome of inappropriate antidiuretic hormone secretion is characterized by impaired water excretion leading to dilutional hyponatremia, which is mainly asymptomatic but may cause neurologic symptoms. Syndrome of inappropriate antidiuretic hormone secretion should be suspected in any patient with hyponatremia, hypo-osmolality, and high urine osmolality.
Foot deformities in children include congenital or acquired malformations of the feet. Two common examples are talipes equinovarus, commonly known as clubfoot, and metatarsus adductus, also called metatarsus varus. Depending on their etiology, foot deformities can be self-limiting or may require surgical correction. Early detection and recognition are crucial for proper treatment.
Blount’s disease (BD) is an orthopedic childhood disorder characterized by outward bowing of the leg due to abnormal ossification of the medial aspect of the tibial epiphysis. Blount’s disease mostly affects children of African descent and tends to debut at approximately 1–3 years of age. Diagnosis is made by clinical findings and is confirmed by imaging. The goal of treatment is to correct the anatomy through bracing or surgical repair, according to the severity and age of the patient at diagnosis. The prognosis is excellent if treatment is promptly started.
Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. The timing and severity of presentation usually depend on the degree of right ventricular outflow obstruction. Definitive diagnosis is usually established by echocardiogram. Chest X-ray may show the classic boot-shaped heart. Definitive treatment involves surgical repair. Long-term prognosis is good for surgically corrected disease, but cardiovascular morbidity is common.
Abdominal injuries are classified according to their mechanism of injury as blunt or penetrating. In blunt abdominal trauma, the bowel, spleen, liver, kidneys, and pelvic organs can be injured. The extent and specific type of abdominal traumatic injury can be identified by a proper history and physical examination and confirmed by appropriate imaging studies. Management depends on the patient’s stability and specific type of injury.
Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. The majority of cases are mild, but presentation can vary from a mild concussion to a comatose state depending on the severity of the insult. Management ranges from observation to intensive care monitoring and neurosurgical interventions. Prognosis is good for mild injuries, but severe trauma can result in death or permanent damage.
Kallmann syndrome (KS), also called olfacto-genital syndrome, is a genetic condition that causes hypogonadotropic hypogonadism due to decreased secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus. Both sexes can be affected, although the incidence is much higher in males. The lack of sex hormones results in impaired pubertal development. Characteristically, there is an associated absence or decreased sense of smell (hyposmia or anosmia), which helps differentiate KS from other conditions. The diagnosis is made by hormone levels in blood and brain imaging showing the absence of olfactory structures. Genetic testing may assist in establishing a definite diagnosis. Treatment consists of hormone replacement therapy.
True hermaphroditism, or ovotesticular disorder of sexual development (ODSD), is characterized by the presence of an ovotesticular gonad that contains both ovarian and testicular elements. Individuals are usually born with ambiguous genitalia, but the diagnosis is rarely confirmed before puberty. The most common karyotype is 46,XX, and less often, 46,XY can be identified. Gonadal biopsy with histologic examination confirms the diagnosis. Management needs to consider the individual’s preferences wherever possible. Treatment options range from hormone replacement to surgical removal of part of the ovotestis gonad to improve fertility and to decrease the risk of malignancies.
Megacolon is a severe, abnormal dilatation of the colon, and is classified as acute or chronic. There are many etiologies of megacolon, including neuropathic and dysmotility conditions, severe infections, ischemia, and inflammatory bowel disease. Toxic megacolon is an acute form of megacolon with systemic toxicity, and carries the highest morbidity and mortality. Common symptoms include abdominal distention, pain, bloody diarrhea, or obstipation. Diagnosis depends on the underlying cause, and is usually established with a combination of the patient’s history, laboratory findings, and imaging studies. Patients with chronic megacolon may require laxatives, enemas, and bowel training. Management for acute megacolon includes supportive care, decompression, and potential surgery.
Colorectal cancer (CRC) is the 2nd leading cause of cancer-related deaths in the United States. Colorectal cancer is a heterogeneous disease that arises from genetic and epigenetic abnormalities, with influence from environmental factors. Almost all cases of CRC are adenocarcinoma, and the majority of lesions come from the malignant transformation of an adenomatous polyp. Since most CRC cases are asymptomatic, screening colonoscopy or stool tests are generally recommended in patients ≥ 50 years of age. Along with screening, diagnosis is reached by colonoscopy, which allows visualization as well as tissue sampling. Treatment is primarily surgical, with chemotherapy reserved for advanced disease.
Barrett’s esophagus is a chronic gastroesophageal reflux disease (GERD) that leads to the replacement of stratified squamous epithelium with gastric columnar epithelium in the esophagus. The condition is associated with an increased risk of esophageal adenocarcinoma. Workup includes an esophagogastroduodenoscopy (EGD) showing proximal displacement of the squamocolumnar junction (Z-line) from the gastroesophageal junction (GEJ). Biopsies will confirm the diagnosis by revealing columnar epithelium and goblet cells in the distal esophagus. Treatment is primarily with proton pump inhibitors (PPIs) and lifestyle modifications. Surveillance with repeated EGD and biopsy is necessary to monitor for early signs of dysplasia.
Gastroesophageal reflux disease (GERD) occurs when the stomach acid frequently flows back into the esophagus. This backwash (acid reflux) can irritate the lining of the esophagus, causing symptoms such as retrosternal burning pain (heartburn). This condition may eventually lead to inflammation (esophagitis), metaplasia (Barrett’s esophagus), and progression to esophageal cancer. Uncomplicated GERD can be managed with lifestyle changes and over-the-counter medications. Sometimes, however, stronger medications or surgery may be required to ease symptoms and prevent complications.
Osteogenesis imperfecta (OI), or “brittle bone disease,” is a rare genetic connective tissue disorder characterized by severe bone fragility. Although OI is considered a single disease, OI includes over 16 genotypes and clinical phenotypes with differing symptom severity. Of these 16, types I–IV are the most common. Because of the rarity of OI, OI is considered an “orphan disease” in the United States. Diagnosis is made clinically, through history and examination, and is confirmed by radiologic findings and DNA analysis. While there is no definitive cure, treatment is supportive, usually involving bisphosphonates, and is focused on reducing pain, reducing fracture frequency, reducing bony deformity, and increasing ambulation. The prognosis is variable, depending on the OI type.
Prostate cancer is one of the most common cancers affecting men. In the United States, the lifetime risk of being diagnosed with prostate cancer is around 11%, and the lifetime risk of dying from this condition is 2.5%. Prostate cancer is a slow-growing cancer that takes years (even decades) to develop into advanced disease, and many men remain asymptomatic and die from other medical conditions.
Cardiopulmonary resuscitation (CPR) is an emergency procedure used in patients with cardiac arrest. Cardiopulmonary resuscitation combines the use of chest compressions, artificial ventilation, and, when available, an automatic external defibrillator (AED) to maintain circulatory flow and oxygenation to vital structures. Cardiopulmonary resuscitation is an integral part of basic life support (BLS) and advanced cardiovascular life support (ACLS). High-quality CPR improves the likelihood of survival. Some patients in critical situations request a do not resuscitate (DNR) order, which instructs health care providers not to do CPR if a patient suffers cardiac arrest.
A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Symptom severity depends on the degree of the collapsed lung. A large or tension pneumothorax can result in cardiopulmonary collapse. A diagnosis is made with imaging, though tension pneumothorax is a clinical diagnosis. Management is based on the size and stability of the patient, and can include needle decompression and chest tube (thoracostomy) placement.
Esophagitis is the inflammation or irritation of the esophagus. The major types of esophagitis are medication-induced, infectious, eosinophilic, corrosive, and acid reflux. Patients typically present with odynophagia, dysphagia, and retrosternal chest pain. Diagnosis is by endoscopy and biopsy. Laboratory tests and imaging are obtained, depending on the degree of damage and involvement of other organ systems. Treatment for esophagitis depends on the underlying etiology and includes dietary changes, avoidance of offending agents, antibiotic therapy, or proton pump inhibitor use. In severe cases such as in corrosive injury, surgery may need to be performed. If left untreated, esophagitis can lead to complications such as strictures, metaplasia of the esophagus, and development of malignancy.
Hyperprolactinemia is defined as a condition of elevated levels of prolactin (PRL) hormone in the blood. The PRL hormone is secreted by the anterior pituitary gland and is responsible for breast development and lactation. Many factors contribute to the development of hyperprolactinemia. The most common cause is PRL-secreting pituitary adenomas (prolactinomas). Diagnosis is achieved through hormonal testing to rule out other endocrine conditions and confirmatory imaging tests. Dopamine agonists are the 1st-line drugs for treatment. Refractory cases require surgery and possibly radiation therapy.
Primary sclerosing cholangitis (PSC) is an inflammatory disease that causes fibrosis and strictures of the bile ducts. The exact etiology is unknown, but there is a strong association with inflammatory bowel disease (IBD). Patients typically present with an insidious onset of fatigue, pruritus, and jaundice, which can progress to cirrhosis and complications related to biliary obstruction. The diagnosis is established with magnetic resonance cholangiopancreatography (MRCP) or endoscopic retrograde cholangiopancreatography (ERCP). Liver transplantation is the only definitive treatment and is indicated in patients with advanced liver disease.
Diverticula are protrusions of the bowel wall occurring most commonly in the colon. The condition of having diverticula (called diverticulosis) is mostly asymptomatic. These diverticula can become symptomatic, however, when associated with diseases. Diverticulitis is the inflammation of diverticula, often presenting with lower abdominal pain and changes in bowel habits. The condition may be further complicated by abscess, perforation, fistula, and bowel obstruction. Management consists of antibiotics, fluid resuscitation, and bowel rest. Surgery is required for complications, failure of medical management, and recurrent disease. In most cases of diverticular bleeding, spontaneous cessation occurs. Invasive intervention will be needed for persistent or recurrent bleeding.
Peripheral artery disease (PAD) is obstruction of the arterial lumen resulting in decreased blood flow to the distal limbs. The disease can be a result of atherosclerosis or thrombosis. Patients may be asymptomatic or have progressive claudication, skin discoloration, ischemic ulcers, or gangrene. Onset may be insidious (atherosclerosis) or abrupt (thrombosis). Diagnosis is made with the clinical history, exam, and measurement of the ankle-brachial index. Imaging studies can determine the location and extent of the arterial disease. Treatment varies depending on the severity but can include lifestyle modifications, antiplatelet therapy, risk factor modifications, phosphodiesterase inhibitors, and revascularization.
Ectopic pregnancy refers to the implantation of a fertilized egg (embryo) outside the uterine cavity. The main cause is disruption of the normal anatomy of the fallopian tube. Consequently, affected patients may suffer from acute abdominal pain as the developing embryo increases in size. Ectopic pregnancy can be quickly diagnosed by means of an ultrasound and laboratory analysis. Management can be expectant, medical, or surgical. Severe cases involving rupture of the fallopian tube and hemorrhage are considered a medical emergency and require immediate surgery.
Appendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting. The diagnosis can frequently be established clinically, but imaging is used in uncertain cases. Computed tomography (CT) scan provides the highest diagnostic accuracy. Perforation occurs in 13%–20% of cases and can present as localized (abscess/phlegmon) or free perforation with generalized peritonitis. The standard treatment is appendectomy, but localized perforations are frequently managed non-operatively with antibiotics.
Drug-induced liver injury (DILI) is the most common cause of acute liver failure (ALF). Hepatotoxic drugs can cause injury to the hepatocytes directly in a predictable dose-dependent way or through idiosyncratic reactions (which may be mediated by immune or non-immune processes). The injury mechanisms can have the following effects: hepatitis, cholestasis, vascular lesions, or overlapping changes. The presentation can be acute or chronic, with severe toxicity manifesting as fulminant liver failure. The diagnosis of DILI requires a thorough history and laboratory tests including liver function tests (LFTs) and drug levels, if available. Management consists of discontinuing the drug, supportive therapy, and monitoring for complications. Acetaminophen, 1 of the most common causes of DILI, has a specific treatment, N-acetylcysteine (NAC).
Supraventricular tachycardias are related disorders in which the elevation in heart rate is driven by pathophysiology in the atria. This group falls under the larger umbrella of tachyarrhythmias and includes paroxysmal supraventricular tachycardias (PSVTs), ventricular pre-excitation syndromes (i.e. Wolff-Parkinson-White syndrome), atrial flutter, multifocal atrial tachycardia, and atrial fibrillation. Sinus tachycardia (> 100/min) is not a pathologic arrhythmia. The diagnosis of these conditions can be made using electrocardiogram (ECG), and treatment differs depending on the condition.
Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS) are serious, acute complications of diabetes mellitus. Diabetic ketoacidosis is characterized by hyperglycemia and ketoacidosis due to an absolute insulin deficiency. Hyperosmolar hyperglycemic state occurs due to a relative deficiency of insulin or insulin resistance, leading to severe hyperglycemia and elevated serum osmolality. Triggering factors include inadequate insulin therapy, underlying infection, concurrent medical illness, or drug side effects. Diabetic ket