Pediatric Gastrointestinal Abnormalities

Introduction

Key considerations in pediatric imaging

Several additional issues must be considered during pediatric imaging, including:

• Limiting/avoiding radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma exposure as much as possible → CT scans are avoided
• Can the individual hold still for the image without sedation? → MRI scans are usually avoided/not needed, especially in young children
• Best imaging modalities:
  • Ultrasound
  • Plain radiography
  • Fluoroscopy Fluoroscopy Production of an image when x-rays strike a fluorescent screen. X-rays

Preparatory steps prior to image analysis

Prior to the interpretation of any image, the physician should take certain preparatory steps. The same systematic approach should always be followed:

• Confirm the name, date, and time on all images.
• Obtain the individual’s medical history and physical examination findings.
• Confirm the appropriate exam and technique for the desired pathology.
• Compare any available images of the same area previously taken using the same modality.
• Determine image orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment:
  • Right or left marker on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests
  • In the US, standard exam views place a marker (dot) to the right side of the subject.
  • For CT/MRI: On axial Axial Computed Tomography (CT) view, the image is sliced and viewed from inferior to superior (as if you are looking from the subject’s feet up).

Radiography/Fluoroscopy

Indications

• Abdominal distension
• Abnormal bowel movements (chronic constipation Constipation 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. Constipation, diarrhea Diarrhea 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. Diarrhea, etc ETC The electron transport chain (ETC) sends electrons through a series of proteins, which generate an electrochemical proton gradient that produces energy in the form of adenosine triphosphate (ATP). Electron Transport Chain (ETC).)
• Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics/ vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia
• History of ingested foreign object
• Suspected (or potential) bowel obstruction Bowel obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Ascaris/Ascariasis or perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis
• Palpable mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
• Trauma
• Verification of correct placement of IVs, lines, and tubes

Advantages

• Low cost
• Relatively low radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma dose
• Ubiquitous availability
• Rapid
• Portable

Disadvantages

• Often nonspecific
• Poor resolution of soft tissue Soft Tissue Soft Tissue Abscess
• Exposure to ionizing radiations
• Subjects must hold still during image acquisition.

Exam technique

• The subject should remain still during image acquisition.
• Arms should be held away from the abdomen (e.g., down at the sides or above the head).
• Remove radiopaque Radiopaque An object of high density that blocks X-rays (looks white) X-rays items (e.g., wet diapers).
• Obtain image during inspiration Inspiration Ventilation: Mechanics of Breathing (ideal).
• Anteroposterior (AP) images:
  • Can be acquired with the subject supine or upright (upright is better for evaluating bowel obstruction Bowel obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Ascaris/Ascariasis and free air)
  • No rotation Rotation Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. X-rays of shoulders or hips; the following should be symmetric:
    • Pedicles of the spine Spine 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. Vertebral Column: Anatomy
    • Ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy
    • Iliac crests
    • Obturator foramen
  • Board should be against the back.
  • X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests beams in the anterior → posterior direction through the subject
• For lateral decubitus images:
  • The subject should be lying on their side.
  • The board should be against the subject’s back (held up by an assistant).
  • Usually left lateral decubitus (i.e., left side down on table) allows better visualization of free air.
• Field of view:
  • Image should be centered in the midline at the level of the iliac crests.
  • Superiorly: Include at least up to the full diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy.
  • Inferiorly: inferior pubic rami
  • Laterally: lateral edges of the abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen
• Visualization:
  • Bowel gas Bowel Gas Imaging of the Intestines should be completely radiolucent Radiolucent An object of low density that is permeable to X-rays (looks black) X-rays.
  • Peritoneal fat planes Peritoneal Fat Planes Imaging of the Intestines should be visible laterally.

Interpretation/evaluation

Images should always be interpreted using a systematic approach.

• Follow the steps in the introduction (e.g., confirm subject’s name, medical history, image orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment, and correct study for the suspected pathology).
• Assess adequacy of the image:
  • Rotation Rotation Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. X-rays: Is the subject rotated?
  • Penetration Penetration X-rays is the degree to which the radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma has passed through the body, resulting in a darker or lighter image:
    • Underpenetration: not enough X-rays X-rays X-rays are high-energy particles of electromagnetic radiation used in the medical field for the generation of anatomical images. X-rays are projected through the body of a patient and onto a film, and this technique is called conventional or projectional radiography. X-rays have passed through → unable to differentiate different dense structures → film appears white and features are less apparent
    • Overpenetration: too many X-rays X-rays X-rays are high-energy particles of electromagnetic radiation used in the medical field for the generation of anatomical images. X-rays are projected through the body of a patient and onto a film, and this technique is called conventional or projectional radiography. X-rays have passed through → film appears dark and features are less apparent
• Inside-out approach Inside-Out Approach Imaging of the Lungs and Pleura (central to peripheral):
  • Look at bowel gas Bowel Gas Imaging of the Intestines patterns:
    • Dilation
    • Distribution
    • Wall pattern
  • Look for solid organ silhouettes Solid Organ Silhouettes Imaging of the Urinary System ( liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy, spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: Anatomy, kidney).
  • Look for normal fat planes peripherally.
  • Look for evidence of free intraperitoneal Intraperitoneal Peritoneum: Anatomy air.
  • Evaluate soft tissues for abnormal calcifications (stones, masses in pediatrics).
  • Look at lung bases Bases Usually a hydroxide of lithium, sodium, potassium, rubidium or cesium, but also the carbonates of these metals, ammonia, and the amines. Acid-Base Balance for evidence of consolidation Consolidation Pulmonary Function Tests, effusion, and pneumothoraces.
  • Evaluate osseous structures ( vertebral body Vertebral body Main portion of the vertebra which bears majority of the weight. Vertebral Column: Anatomy height, iliac bones, femurs).
  • Look at tubes and lines.
• If an abnormality is noted → use patterns for differential diagnoses

Normal findings

• Bowel gas Bowel Gas Imaging of the Intestines:
  • Should be present in the small and large bowels
  • Should not distend the small bowel Small bowel 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. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine: Anatomy by > 3 cm
  • Should be uniform throughout the abdomen
• Organs:
  • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy region visible under the right hemidiaphragm should be uniform with no free air.
  • Stomach Stomach 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. Stomach: Anatomy and colon Colon 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. Colon, Cecum, and Appendix: Anatomy are visible with air in the lumen under the left hemidiaphragm.
  • Renal outlines, if visible, should be in the right and left upper quadrants.
• Fat planes: along the periphery
• Lung bases Bases Usually a hydroxide of lithium, sodium, potassium, rubidium or cesium, but also the carbonates of these metals, ammonia, and the amines. Acid-Base Balance:
  • Should be clear with minimal lung markings
  • Costophrenic angles should be sharp.
• Bones:
  • Pedicles should be present and symmetric bilaterally.
  • Vertebral body Vertebral body Main portion of the vertebra which bears majority of the weight. Vertebral Column: Anatomy heights should gradually enlarge as they move inferiorly.
  • Spinous processes should be midline.

Specialized tests

Esophagram, upper GI contrast (i.e., “swallow study”), and small bowel follow-through Small Bowel Follow-Through Imaging of the Intestines studies:

• Radiographic/fluoroscopic images are acquired while swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility barium contrast.
• Esophagram:
  • Focuses primarily on the esophagus Esophagus 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. Esophagus: Anatomy
  • Allows assessment of esophageal function and anatomy of the lumen
  • Indicated in the evaluation of eating/drinking/ swallowing Swallowing The act of taking solids and liquids into the gastrointestinal tract through the mouth and throat. Gastrointestinal Motility difficulties and gastric reflux
• Upper GI radiography:
  • Includes evaluation of the esophagus Esophagus 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. Esophagus: Anatomy, stomach Stomach 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. Stomach: Anatomy, and duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy
  • Helpful in diagnosing malrotation, volvulus Volvulus 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. Volvulus, and/or duodenal atresia Duodenal atresia Failed recanalization of the duodenum during embryonal development. Congenital Duodenal Obstruction
• Small bowel follow-through Small Bowel Follow-Through Imaging of the Intestines:
  • Images are taken at different time points (minutes to hours) following oral contrast → contrast is followed all the way through the small intestine Small intestine 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. It is divided into 3 segments: the duodenum, the jejunum, and the ileum. Small Intestine: Anatomy into the colon Colon 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. Colon, Cecum, and Appendix: Anatomy
  • Usually (though not always) follows an upper GI study
  • Allows assessment of strictures, obstructions, masses, and position of the intestines
• Normal findings:
  • Normal movement of contrast in peristaltic waves down the esophagus Esophagus 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. Esophagus: Anatomy, into the stomach Stomach 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. Stomach: Anatomy, and into the small intestines
  • No reflux
  • No narrowing/strictures
  • Normal position of the organs

Contrast enema

• Radiographic/fluoroscopic images are taken while the contrast is injected into the rectum Rectum 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 continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters. Rectum and Anal Canal: Anatomy via an enema tube.
• Allows assessment of lower GI anatomy
• Contrast may be barium or a water-soluble agent.
• May be indicated for the evaluation of:
  • Chronic constipation Constipation 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. Constipation or diarrhea Diarrhea 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. Diarrhea
  • Difficulties with bowel movements
  • Unexplained weight loss Weight loss Decrease in existing body weight. Bariatric Surgery
  • Suspected pathology:
    • Inflammatory bowel disease
    • Hirschsprung disease Hirschsprung Disease 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. M Hirschsprung Disease

Sitz marker test to determine colonic transit time

• Capsules with a number of small radiopaque Radiopaque An object of high density that blocks X-rays (looks white) X-rays markers are swallowed → radiography performed 3‒5 days later
• Allows assessment of bowel motility Motility The motor activity of the gastrointestinal tract. Gastrointestinal Motility and colonic transit
• Indicated for the evaluation of chronic constipation Constipation 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. Constipation
• Normal findings: All markers should be cleared by 5 days.

Ultrasound

Indications

• Evaluate for suspected/potential conditions:
  • Appendicitis Appendicitis 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. Appendicitis
  • Intussusception Intussusception 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. Intussusception
  • Hypertrophic pylorus Pylorus The region between the sharp indentation at the lower third of the stomach (incisura angularis) and the junction of the pylorus with the duodenum. Pyloric antral glands contain mucus-secreting cells and gastrin-secreting endocrine cells (g cells). Stomach: Anatomy
  • Soft tissue Soft Tissue Soft Tissue Abscess/subcutaneous abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease
• For neonates with abnormalities noted on prenatal ultrasonography
• Known congenital Congenital Chorioretinitis disease with predisposition for certain complications

Advantages

• Low cost 
• No radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma exposure
• Widespread availability
• Rapid

Disadvantages

• Poor resolution
• Narrow field of view
• Subject must hold still during image acquisition.
• Technician dependent

Exam technique

• Positioning:
  • Depends on the area of concern, but usually supine
  • The organ of interest should be most superficial to the probe Probe A device placed on the patient’s body to visualize a target Ultrasound (Sonography) without other organs/bowel between the area of interest and the ultrasound probe Probe A device placed on the patient’s body to visualize a target Ultrasound (Sonography).
  • Maximize contact between the subject’s skin Skin 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. Skin: Structure and Functions and ultrasound probe Probe A device placed on the patient’s body to visualize a target Ultrasound (Sonography).
• Depth:
  • Determines the field of view
  • Should include the entire area of concern without excessive deeper areas
• Gain:
  • Determines echogenicity characteristics of the tissue
  • Solid organ parenchyma should have midrange signal echogenicity.
• Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography): assesses velocity and direction of blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure in an area

Interpretation and evaluation

• Follow the steps in the introduction (e.g., confirming the subject’s name, medical history, image orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment, the correct study for the suspected pathology).
• Assess adequacy of the image:
  • Is the depth and gain appropriate to fully assess the area of concern?
  • Is the entire area of concern imaged in the proper views for full assessment?
• Analyze images:
  • Take measurements of all relevant structures and compare them with standard reference ranges, for example:
    • Size of appendix Appendix A worm-like blind tube extension from the cecum. Colon, Cecum, and Appendix: Anatomy
    • Bowel wall thickness
  • Evaluate echogenicity of the structures:
    • Parenchyma: mid-range echogenicity (medium gray)
    • Serous fluid: hypoechoic Hypoechoic A structure that produces a low-amplitude echo (darker grays) Ultrasound (Sonography)/ anechoic Anechoic A structure that produces no echo at all (looks completely black) Ultrasound (Sonography) (black)
    • “Fresh” blood: more hyperechoic Hyperechoic A structure that produces a high-amplitude echo (lighter grays and white) Ultrasound (Sonography) signals
    • Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types/calcifications: very hyperechoic Hyperechoic A structure that produces a high-amplitude echo (lighter grays and white) Ultrasound (Sonography) (white)
    • Bowel gas Bowel Gas Imaging of the Intestines creates significant shadowing.
  • Comment on any structural abnormalities or masses noted.

Normal findings

• Normal bowel ultrasound:
  • No evidence of abnormal wall thickening or obstruction
  • Pyloric wall should be < 4 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma in thickness.
  • Appendix Appendix A worm-like blind tube extension from the cecum. Colon, Cecum, and Appendix: Anatomy should be < 6 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma in diameter.
  • Normal position of organs and vessels
• Subcutaneous soft tissues:
  • Should be heterogeneous due to the presence of muscle, fascia Fascia Layers of connective tissue of variable thickness. The superficial fascia is found immediately below the skin; the deep fascia invests muscles, nerves, and other organs. Cellulitis, and fat
  • No fluid collection
  • Arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology and veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins: Histology should have appropriate directional flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure.

Pathologic Findings

Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis is hypertrophy and hyperplasia of the pyloric sphincter muscle. The condition is the most common cause of gastrointestinal obstruction in infants. Affected newborns typically present after the third to fifth week of life with progressive non-bilious vomiting and a firm, olive-like mass in the epigastrium. Hypertrophic Pyloric Stenosis

Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis is hypertrophy and hyperplasia of the pyloric sphincter muscle. The condition is the most common cause of gastrointestinal obstruction in infants. Affected newborns typically present after the third to fifth week of life with progressive non-bilious vomiting and a firm, olive-like mass in the epigastrium. Hypertrophic Pyloric Stenosis refers to congenital Congenital Chorioretinitis thickening of the pyloric musculature that produces severe stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS) and near obstruction of the gastric outlet. Children present with nonbilious projectile vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia and an olive-sized mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast in the upper abdomen. Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis Hypertrophic pyloric stenosis is hypertrophy and hyperplasia of the pyloric sphincter muscle. The condition is the most common cause of gastrointestinal obstruction in infants. Affected newborns typically present after the third to fifth week of life with progressive non-bilious vomiting and a firm, olive-like mass in the epigastrium. Hypertrophic Pyloric Stenosis can be treated surgically.

• Ultrasound is the imaging study of choice in suspected cases:
  • Pyloric thickness > 4 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma
  • Target sign Target sign Pseudomembranous Colitis or donut sign: classic cross-sectional appearance of the pylorus Pylorus The region between the sharp indentation at the lower third of the stomach (incisura angularis) and the junction of the pylorus with the duodenum. Pyloric antral glands contain mucus-secreting cells and gastrin-secreting endocrine cells (g cells). Stomach: Anatomy in the shape of a target or donut
  • Elongated pyloric canal
• Upper GI series Upper Gi Series Imaging of the Intestines: only ordered if the exam and ultrasound are nondiagnostic, or if there are other symptoms suggesting more distal obstruction
  • String sign String Sign Hypertrophic Pyloric Stenosis: elongated pyloric canal
  • Double-track sign: 2 thin tracks along the pyloric canal created by compressed pyloric mucosa
  • Beak sign: tapered point at the end of the pyloric canal
  • Shoulder sign Shoulder Sign Hypertrophic Pyloric Stenosis: a prepyloric “bulge” of contrast

Necrotizing enterocolitis Enterocolitis Inflammation of the mucosa of both the small intestine and the large intestine. Etiology includes ischemia, infections, allergic, and immune responses. Yersinia spp./Yersiniosis ( NEC NEC 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. Necrotizing Enterocolitis)

Necrotizing enterocolitis Enterocolitis Inflammation of the mucosa of both the small intestine and the large intestine. Etiology includes ischemia, infections, allergic, and immune responses. Yersinia spp./Yersiniosis is a relatively common neonatal GI emergency due to infection by gas-forming organisms, which results in ischemic necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage of the intestinal mucosa Intestinal Mucosa Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae. In the small intestine, the mucosa is characterized by a series of folds and abundance of absorptive cells (enterocytes) with microvilli. Small Intestine: Anatomy. Infants typically present with a sudden change in feeding tolerance Tolerance Pharmacokinetics and Pharmacodynamics and abdominal distension in the 1st or 2nd weeks of life.

• Plain radiography (imaging modality of choice)findings:
  • Pneumatosis intestinalis Pneumatosis intestinalis A condition characterized by the presence of multiple gas-filled cysts in the intestinal wall, the submucosa and/or subserosa of the intestine. The majority of the cysts are found in the jejunum and the ileum. Necrotizing Enterocolitis:
    • Pathognomonic for NEC NEC 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. Necrotizing Enterocolitis
    • Presence of gas within the intestinal wall itself
    • Appears as a linear or bubbly pattern
  • Dilated and thickened bowel loops
  • Fixed dilated loops and absence of intestinal gas (gasless abdomen)
• Pneumoperitoneum Pneumoperitoneum A condition with trapped gas or air in the peritoneal cavity, usually secondary to perforation of the internal organs such as the lung and the gastrointestinal tract, or to recent surgery. Pneumoperitoneum may be purposely introduced to aid radiological examination. Perforated Viscus and/or portal venous gas Portal Venous Gas Imaging of the Intestines → indicates bowel necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage and perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis
• Ultrasound is used as a 2nd-line test:
  • Bowel wall thickening
  • Hyperechoic Hyperechoic A structure that produces a high-amplitude echo (lighter grays and white) Ultrasound (Sonography) foci within bowel walls → represents intramural gas
  • Free fluid (especially with echogenic debris) → suggests perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis
• Note: Barium enemas are contraindicated in NEC NEC 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. Necrotizing Enterocolitis as they may cause bowel perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis.

Midgut Midgut Development of the Abdominal Organs malrotation and volvulus Volvulus 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. Volvulus

• Midgut Midgut Development of the Abdominal Organs malrotation is the abnormal position and fixation of the intestine due to abnormal gut tube rotation Rotation Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. X-rays during fetal development:
  • Anatomy varies based on the different rotational abnormalities during development.
  • Abnormal positioning of the duodenojejunal junction:
    • Normal anatomy: lies to the left of the midline
    • Anatomy in malrotation: most commonly to the right of the midline
  • Abnormal positioning of the ileocecal junction:
    • Normal anatomy: lies in the right lower quadrant Right lower quadrant Anterior Abdominal Wall: Anatomy (RLQ)
    • Anatomy in malrotation: most commonly ends up in the right mid-upper abdomen, fixated to the abdominal wall Abdominal wall The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis. Though its major part is muscular, the abdominal wall consists of at least seven layers: the skin, subcutaneous fat, deep fascia; abdominal muscles, transversalis fascia, extraperitoneal fat, and the parietal peritoneum. Surgical Anatomy of the Abdomen and potentially obstructing the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy
  • If symptomatic, most commonly presents with bilious vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia and abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways.
  • Predisposes to volvulus Volvulus 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. Volvulus
• Volvulus Volvulus 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. Volvulus:
  • Twisting of the intestines around its mesentery Mesentery A layer of the peritoneum which attaches the abdominal viscera to the abdominal wall and conveys their blood vessels and nerves. Peritoneum: Anatomy, resulting in bowel obstruction Bowel obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Ascaris/Ascariasis
  • Requires emergent surgical intervention
• Ultrasound:
  • Best initial exam for screening Screening Preoperative Care and diagnosis
  • Better at diagnosing volvulus Volvulus 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. Volvulus than malrotation
  • Findings include:
    • Abnormal position of the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy and/or superior mesenteric vein
    • Whirlpool sign Whirlpool sign Twisting of the superior mesenteric vein and the mesentery around the superior mesenteric artery. Intestinal Malrotation on Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography): caused by vessels twisting around the base of the mesentery Mesentery A layer of the peritoneum which attaches the abdominal viscera to the abdominal wall and conveys their blood vessels and nerves. Peritoneum: Anatomy in volvulus Volvulus 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. Volvulus
    • Dilated duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy (indicates obstruction)
• Plain radiography:
  • Rarely helps with diagnosis, but should be ordered to exclude intestinal perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis and pneumoperitoneum Pneumoperitoneum A condition with trapped gas or air in the peritoneal cavity, usually secondary to perforation of the internal organs such as the lung and the gastrointestinal tract, or to recent surgery. Pneumoperitoneum may be purposely introduced to aid radiological examination. Perforated Viscus
  • Volvulus Volvulus 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. Volvulus may show dilated loops of bowel and air fluid levels Air Fluid Levels Imaging of the Intestines, indicating obstruction.
  • Finding that is diagnostic of malrotation/ volvulus Volvulus 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. Volvulus: directly visualizing the abnormal duodenal position by passing a nasogastric tube Nasogastric tube Malnutrition in children in resource-limited countries through the area
• Upper GI contrast series:
  • Gold standard for the definitive diagnosis of both malrotation and volvulus Volvulus 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. Volvulus
  • Obtained if ultrasound findings are equivocal (or negative) but malrotation/ volvulus Volvulus 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. Volvulus is still suspected
  • Malrotation findings: Duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy stays to the right of the spine Spine 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. Vertebral Column: Anatomy.
  • Volvulus Volvulus 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. Volvulus:
    • Corkscrew appearance of the duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy and jejunum Jejunum The middle portion of the small intestine, between duodenum and ileum. It represents about 2/5 of the remaining portion of the small intestine below duodenum. Small Intestine: Anatomy
    • Duodenal obstruction (no contrast passage)
• Small bowel follow-through Small Bowel Follow-Through Imaging of the Intestines: may show abnormal position of the ileocecal junction

Intestinal atresia Atresia Hypoplastic Left Heart Syndrome (HLHS)

Intestinal atresia Atresia Hypoplastic Left Heart Syndrome (HLHS) is a condition in which a portion of intestine fails to canalize during development, resulting in bowel obstruction Bowel obstruction Any impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal. Ascaris/Ascariasis in newborns. Approximately ½ of all cases constitute duodenal atresia Duodenal atresia Failed recanalization of the duodenum during embryonal development. Congenital Duodenal Obstruction. Infants present with vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia and abdominal distension. Surgery is the definitive treatment.

• Plain radiography:
  • Double bubble sign:
    • 2 “bubbles” of air are seen representing dilation of the stomach Stomach 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. Stomach: Anatomy and proximal duodenum Duodenum The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. It is named for having the length equal to about the width of 12 fingers. Small Intestine: Anatomy.
    • Strongly suggests duodenal atresia Duodenal atresia Failed recanalization of the duodenum during embryonal development. Congenital Duodenal Obstruction
  • Pneumoperitoneum Pneumoperitoneum A condition with trapped gas or air in the peritoneal cavity, usually secondary to perforation of the internal organs such as the lung and the gastrointestinal tract, or to recent surgery. Pneumoperitoneum may be purposely introduced to aid radiological examination. Perforated Viscus may be seen → represents intestinal perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis
  • Air-fluid levels
• Upper GI contrast study with/without small bowel follow-through Small Bowel Follow-Through Imaging of the Intestines:
  • Identifies the location of atresia Atresia Hypoplastic Left Heart Syndrome (HLHS)
  • Differentiates intestinal atresia Atresia Hypoplastic Left Heart Syndrome (HLHS) from obstruction due to malrotation with volvulus Volvulus 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. Volvulus
• Contrast enema:
  • Obtained if the above studies fail to diagnose the cause of obstruction
  • Differentiates colonic atresia Atresia Hypoplastic Left Heart Syndrome (HLHS) from obstruction due to Hirschsprung disease Hirschsprung Disease 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. M Hirschsprung Disease

Intussusception Intussusception 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. Intussusception

Intussusception Intussusception 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. Intussusception: telescoping of a distal segment of the bowel into a more proximal segment, most often in the ileocolic region. Intussusception Intussusception 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. Intussusception is the most common abdominal emergency in children < 2 years of age, which presents with the “classic triad” of sudden onset crampy abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, a palpable sausage-shaped mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast, and currant jelly stools.

• Ultrasound:
  • Often the diagnostic test of choice
  • Excellent sensitivity, specificity, and negative predictive value Negative predictive value The NPV is the percentage of people with a negative test result who are actually disease free, among all people with a negative result regardless of whether or not they have the disease. Epidemiological Values of Diagnostic Tests ( NPV NPV The NPV is the percentage of people with a negative test result who are actually disease free, among all people with a negative result regardless of whether or not they have the disease. Epidemiological Values of Diagnostic Tests) when performed by an experienced sonographer
  • Can detect the pathologic lead points that may have caused the intussusception Intussusception 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. Intussusception
  • Key finding is a “target” sign (most often in the RLQ):
    • Also called a bull’s eye or coiled spring sign
    • Represents layers of intestine within the intestine
  • ↓ Perfusion on color Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography) → indicates ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage
• Plain radiography:
  • Nondiagnostic for intussusception Intussusception 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. Intussusception itself
  • Should be ordered to exclude perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis and for screening Screening Preoperative Care of other pathologies
  • Possible findings:
    • Crescent Crescent Rapidly Progressive Glomerulonephritis (meniscus) sign: soft tissue Soft Tissue Soft Tissue Abscess density ( intussusception Intussusception 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. Intussusception) projecting into the gas of the large bowel
    • Signs of small bowel obstruction Small Bowel Obstruction 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. Small Bowel Obstruction: distended loops of bowel with absent colonic gas
• Management:
  • In stable individuals, intussusception Intussusception 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. Intussusception is usually managed with nonoperative reduction (e.g., an air enema) delivered under fluoroscopic or sonographic guidance.
  • Surgery is indicated for:
    • Unstable individuals
    • Cases complicated by intestinal perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis or peritonitis Peritonitis Inflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs. Penetrating Abdominal Injury
    • Unsuccessful nonoperative reduction

Meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate ileus Ileus A condition caused by the lack of intestinal peristalsis or intestinal motility without any mechanical obstruction. This interference of the flow of intestinal contents often leads to intestinal obstruction. Ileus may be classified into postoperative, inflammatory, metabolic, neurogenic, and drug-induced. Small Bowel Obstruction

Obstruction of the terminal ileum Ileum The distal and narrowest portion of the small intestine, between the jejunum and the ileocecal valve of the large intestine. Small Intestine: Anatomy by abnormally thick and sticky meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate. Meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate ileus Ileus A condition caused by the lack of intestinal peristalsis or intestinal motility without any mechanical obstruction. This interference of the flow of intestinal contents often leads to intestinal obstruction. Ileus may be classified into postoperative, inflammatory, metabolic, neurogenic, and drug-induced. Small Bowel Obstruction is often seen in neonates with cystic Cystic Fibrocystic Change fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans and Hirschsprung disease Hirschsprung Disease 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. M Hirschsprung Disease. Affected neonates usually present with vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, failure to pass meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate within 12‒24 hours, and abdominal distension.

• Plain radiography: to rule out perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis and other abnormalities
• Contrast enema:
  • Diagnostic and therapeutic
  • Small caliber colon Colon 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. Colon, Cecum, and Appendix: Anatomy due to disuse
  • Meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate pellets can be seen in the terminal ileum Ileum The distal and narrowest portion of the small intestine, between the jejunum and the ileocecal valve of the large intestine. Small Intestine: Anatomy.
  • Often releases the plug (otherwise, surgery is required)

Hirschsprung disease Hirschsprung Disease 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. M Hirschsprung Disease

Also known as congenital Congenital Chorioretinitis aganglionic megacolon Megacolon 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. Megacolon, Hirschsprung disease Hirschsprung Disease 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. M Hirschsprung Disease is characterized by the absence of nerve cells in the distal colon Colon 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. Colon, Cecum, and Appendix: Anatomy, resulting in failure of the affected segment to relax, leading to functional obstruction. Affected neonates present with bilious emesis, abdominal distension, and failure to pass meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate. Associated enterocolitis Enterocolitis Inflammation of the mucosa of both the small intestine and the large intestine. Etiology includes ischemia, infections, allergic, and immune responses. Yersinia spp./Yersiniosis is common.

• Plain radiography:
  • Dilated proximal colon Colon 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. Colon, Cecum, and Appendix: Anatomy with collapsed distal colon Colon 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. Colon, Cecum, and Appendix: Anatomy/ rectum Rectum 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 continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters. Rectum and Anal Canal: Anatomy
  • Rules out perforation Perforation A pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force. Esophagitis
  • Normal films do not exclude the diagnosis.

• Contrast enema is the best radiologic test:
  • Pathognomonic finding: presence of a transition zone between the distended normal proximal bowel and narrow aganglionic distal segments
    • The site of the transition zone depends on the extent of intestinal involvement, but is usually in the rectosigmoid area.
    • May be absent: Normal films do not exclude the diagnosis.
  • Meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate plugs may be seen as multiple filling defects Filling Defects Imaging of the Intestines within the colon Colon 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. Colon, Cecum, and Appendix: Anatomy.
• Other diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests:
  • Anorectal manometry Manometry Measurement of the pressure or tension of liquids or gases with a manometer. Achalasia
  • Definitive diagnosis requires a rectal biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma, which should be obtained prior to surgery.

Appendicitis Appendicitis 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. Appendicitis

Appendicitis Appendicitis 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. Appendicitis is the inflammation Inflammation 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. Inflammation of the appendix Appendix A worm-like blind tube extension from the cecum. Colon, Cecum, and Appendix: Anatomy, which characteristically presents with periumbilical pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways migrating to the RLQ with guarding, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics/ vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia, and fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever. In children, the diagnosis is usually clinical with/without the use of ultrasound. Management is usually surgical.

• Ultrasonography: Appendicitis Appendicitis 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. Appendicitis cannot be reliably excluded unless the appendix Appendix A worm-like blind tube extension from the cecum. Colon, Cecum, and Appendix: Anatomy is definitively seen.
  • Noncompressible tubular structure in the RLQ
  • Wall thickness > 2 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma
  • Overall diameter > 6 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma
  • Hyperemia
  • Calcified fecalith Fecalith Imaging of the Intestines
• Can consider CT and/or MRI if the ultrasound is nondiagnostic. Findings are similar to those from ultrasound, although CT/MRI have higher sensitivity/specificity.

Mesenteric lymphadenitis Lymphadenitis Inflammation of the lymph nodes. Peritonsillar Abscess

Mesenteric lymphadenitis Lymphadenitis Inflammation of the lymph nodes. Peritonsillar Abscess refers to inflammation Inflammation 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. Inflammation in the mesenteric lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs nodes (usually in the RLQ) that often occurs when the enteric immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs reacts strongly to an infection (e.g., viral infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, Yersinia enterocolitica Yersinia enterocolitica A species of the genus yersinia, isolated from both man and animal. It is a frequent cause of bacterial gastroenteritis in children. Yersinia spp./Yersiniosis infection). Stretching of the lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs node capsules can result in pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways similar to that experienced in appendicitis Appendicitis 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. Appendicitis; however, mesenteric lymphadenitis Lymphadenitis Inflammation of the lymph nodes. Peritonsillar Abscess is self-limiting Self-Limiting Meningitis in Children.

• Ultrasonography:
  • Enlarged lymph Lymph The interstitial fluid that is in the lymphatic system. Secondary Lymphatic Organs nodes > 8 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma in diameter
  • With/without ileocecal wall thickening
  • Normal appendix Appendix A worm-like blind tube extension from the cecum. Colon, Cecum, and Appendix: Anatomy

Obstructive biliary tract Biliary tract 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. Gallbladder and Biliary Tract: Anatomy disorders

Two significant biliary tract Biliary tract 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. Gallbladder and Biliary Tract: Anatomy disorders that can cause obstruction include biliary atresia Atresia Hypoplastic Left Heart Syndrome (HLHS) and choledochal cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change. Both present with obstructive jaundice Jaundice Jaundice is the abnormal yellowing of the skin and/or sclera caused by the accumulation of bilirubin. Hyperbilirubinemia is caused by either an increase in bilirubin production or a decrease in the hepatic uptake, conjugation, or excretion of bilirubin. Jaundice and acholic stools. Treatment is surgical.

• Biliary atresia Atresia Hypoplastic Left Heart Syndrome (HLHS): an idiopathic Idiopathic Dermatomyositis progressive disorder in neonates characterized by obliterating fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans of the extrahepatic biliary tree Biliary tree The bile ducts and the gallbladder. Gallbladder and Biliary Tract: Anatomy
• Choledochal cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change: congenital Congenital Chorioretinitis anomalies of the bile Bile An emulsifying agent produced in the liver and secreted into the duodenum. Its composition includes bile acids and salts; cholesterol; and electrolytes. It aids digestion of fats in the duodenum. Gallbladder and Biliary Tract: Anatomy duct cyst that cause abnormal enlargement and obstruction of the intrahepatic and/or extrahepatic bile ducts Extrahepatic bile ducts Passages external to the liver for the conveyance of bile. These include the common bile duct and the common hepatic duct. Gallbladder and Biliary Tract: Anatomy
• Ultrasound:
  • Findings of biliary atresia Atresia Hypoplastic Left Heart Syndrome (HLHS) may include:
    • Absence or irregular shape of the gallbladder Gallbladder 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. Gallbladder and Biliary Tract: Anatomy
    • Triangular cord sign: a triangular echogenic area just above the porta hepatis Porta hepatis Liver: Anatomy
    • Polysplenia may be present.
  • Findings of choledochal cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change: hypoechoic Hypoechoic A structure that produces a low-amplitude echo (darker grays) Ultrasound (Sonography) masses seen
  • Also used to exclude other causes of cholestasis (e.g., gallstones Gallstones Cholelithiasis (gallstones) is the presence of stones in the gallbladder. Most gallstones are cholesterol stones, while the rest are composed of bilirubin (pigment stones) and other mixed components. Patients are commonly asymptomatic but may present with biliary colic (intermittent pain in the right upper quadrant). Cholelithiasis)
• Intraoperative cholangiogram:
  • Contrast is injected into the biliary tree Biliary tree The bile ducts and the gallbladder. Gallbladder and Biliary Tract: Anatomy and radiographic images are acquired.
  • Gold standard for the diagnosis of biliary atresia Atresia Hypoplastic Left Heart Syndrome (HLHS)