Hydronephrosis

Diagnosis

The diagnosis of hydronephrosis is made by imaging, which also often identifies the cause. History, exam, and lab findings can help suggest the underlying etiology as well.

History

• 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
• Hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma
• Symptoms of lower urinary tract obstruction Urinary tract obstruction Urinary tract obstruction (UTO) refers to the blockage of the urinary tract, which can occur anywhere in the urinary tract. Urinary tract obstruction can be acute or chronic, partial or complete, and unilateral or bilateral. Urinary tract obstruction can cause acute or chronic kidney disease. Urinary Tract Obstruction:
  • Hesitancy
  • Dribbling
  • Prolonged micturition
  • Weak stream
• Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways:
  • Location
  • Quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement 
  • Duration
  • 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
• Symptoms of urinary tract Urinary tract 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. Urinary Tract: Anatomy infection:
  • Dysuria Dysuria Painful urination. It is often associated with infections of the lower urinary tract. Urinary tract infections (UTIs)
  • Urgency
  • Incontinence
• 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 and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia

Physical exam findings

The following exam findings, if present, can help identify the cause of hydronephrosis:

• Costovertebral angle tenderness (suggests nephrolithiasis Nephrolithiasis 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 or upper tract infection)
• Abdominal examination Abdominal examination 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. Abdominal Examination:
  • Palpable kidney or bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess
  • Tenderness
• Digital rectal examination Digital Rectal Examination A physical examination in which the qualified health care worker inserts a lubricated, gloved finger of one hand into the rectum and may use the other hand to press on the lower abdomen or pelvic area to palpate for abnormalities in the lower rectum, and nearby organs or tissues. The method is commonly used to check the lower rectum, the prostate gland in men, and the uterus and ovaries in women. Prostate Cancer Screening:
  • Prostatic enlargement
  • Prostatic nodules
  • Sphincter tone
• Pelvic exam (women):
  • Pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
  • Pelvic mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast

Diagnostic testing

Laboratory studies:

• Urinalysis Urinalysis Examination of urine by chemical, physical, or microscopic means. Routine urinalysis usually includes performing chemical screening tests, determining specific gravity, observing any unusual color or odor, screening for bacteriuria, and examining the sediment microscopically. Urinary Tract Infections (UTIs) in Children:
  • Pyuria Pyuria The presence of white blood cells (leukocytes) in the urine. It is often associated with bacterial infections of the urinary tract. Pyuria without bacteriuria can be caused by tuberculosis, stones, or cancer. Urinary tract infections (UTIs) suggests the presence of 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.
  • Leukocyte esterase Leukocyte esterase Kidney Function Tests or nitrites indicate infection.
  • Hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma may indicate the presence of stones, malignancy Malignancy Hemothorax, or infection.
• Basic metabolic panel Basic Metabolic Panel Primary vs Secondary Headaches:
  • ↑ BUN and creatinine are seen in bilateral hydronephrosis and indicate renal compromise.
  • Hyperkalemia Hyperkalemia 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 and acidosis Acidosis A pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up. Respiratory Acidosis indicate severe renal insufficiency.

Imaging

Diagnostic findings:

• Dilation of the collecting system in 1 or both kidneys Kidneys 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. Kidneys: Anatomy
• Imaging typically assesses:
  • Kidneys Kidneys 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. Kidneys: Anatomy
  • Ureters Ureters One of a pair of thick-walled tubes that transports urine from the kidney pelvis to the urinary bladder. Urinary Tract: Anatomy
  • Bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess
• Notation of dilated structures (and nondilated structures) can help identify the location of the obstruction (e.g., a dilated proximal right ureter with a normal bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess and contralateral structures = right ureteral obstruction Ureteral obstruction Blockage in any part of the ureter causing obstruction of urine flow from the kidney to the urinary bladder. The obstruction may be congenital, acquired, unilateral, bilateral, complete, partial, acute, or chronic. Depending on the degree and duration of the obstruction, clinical features vary greatly such as hydronephrosis and obstructive nephropathy. Vesicoureteral Reflux)

Imaging in adults:

• Ultrasonography:
  • Best 1st-line test in most individuals
  • Preferred over CT for pregnant women
  • Not as sensitive as CT in detecting ureteral stones
  • Primarily used to rule out obstruction and identify abnormal structures
  • Allows for simultaneous assessments of surrounding structures (e.g., prostate Prostate 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. Prostate, Seminal, and Bulbourethral Glands: Anatomy and gynecologic structures)
  • Findings: 
    • Urine Urine Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra. Bowen Disease and Erythroplasia of Queyrat-filled dilated compartments are hypoechoic Hypoechoic A structure that produces a low-amplitude echo (darker grays) Ultrasound (Sonography) (dark)
    • Calcified stones are hyperechoic Hyperechoic A structure that produces a high-amplitude echo (lighter grays and white) Ultrasound (Sonography) (white) with posterior shadowing
    • Can identify damage to the renal parenchyma (e.g., cortical thinning), 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/masses, and urinary retention Urinary retention Inability to empty the urinary bladder with voiding (urination). Delirium.
• CT: 
  • Best imaging method to diagnose stones → 1st-line test when obstructing stones are suspected
  • Provides complementary information to ultrasounds, especially when evaluating 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 and masses
• IV pyelography:
  • Contrast material is injected into the 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 and a series of 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 are taken over the course of approximately 1 hour. 
  • Assess how the contrast material is filtered into and moves through the urinary system.
  • Has low false positive False positive An FP test result indicates that a person has the disease when they do not. Epidemiological Values of Diagnostic Tests rate compared to ultrasonography
  • Used infrequently for follow-up of stones or assessment of anatomy after stone removal

Imaging in children:

• Ultrasonography: 
  • Test of choice in children, infants, and prenatally
  • Grading Grading Methods which attempt to express in replicable terms the level of cell differentiation in neoplasms as increasing anaplasia correlates with the aggressiveness of the neoplasm. Grading, Staging, and Metastasis of antenatal hydronephrosis has been developed for prenatal and postnatal ureteropelvic-junction–type hydronephrosis based on findings.
• Voiding cystourethrography: 
  • The bladder Bladder A musculomembranous sac along the urinary tract. Urine flows from the kidneys into the bladder via the ureters, and is held there until urination. Pyelonephritis and Perinephric Abscess is filled with contrast material via a urethral catheter; fluoroscopic images are then taken while filling and voiding the contrast material.
  • Best imaging study to diagnose suspected vesicoureteral reflux Vesicoureteral Reflux Vesicoureteral reflux (VUR) is the retrograde flow of urine from the bladder into the upper urinary tract. Primary VUR often results from the incomplete closure of the ureterovesical junction, whereas secondary VUR is due to an anatomic or physiologic obstruction. Vesicoureteral Reflux
• Diuretic renography:
  • A radionucleotide and diuretic are injected intravenously and a series of images are taken as the marker moves through the kidney and urinary system.
  • Best for differentiating obstructive vs. nonobstructive hydronephrosis
  • Assesses function of each individual kidney (i.e., how much of the “workload” is done by each kidney)
• Magnetic resonance urography:
  • Better defines the anatomy
  • Used for surgery planning
  • Often requires general anesthesia Anesthesia A state characterized by loss of feeling or sensation. This depression of nerve function is usually the result of pharmacologic action and is induced to allow performance of surgery or other painful procedures. Anesthesiology: History and Basic Concepts or heavy sedation in children

Management

Management depends on the cause of obstruction, the degree of metabolic abnormality, and the presence of infection.

General recommendations

• Analgesia Analgesia Methods of pain relief that may be used with or in place of analgesics. Anesthesiology: History and Basic Concepts:
  • NSAIDs NSAIDS Primary vs Secondary Headaches (1st line)
  • Acetaminophen Acetaminophen 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. Acetaminophen
  • Oxycodone Oxycodone A semisynthetic derivative of codeine. Opioid Analgesics
  • Hydrocodone Hydrocodone Opioid Analgesics
• Fluid replacement
• Antibiotics if infection present:
  • Trimethoprim–sulfamethoxazole Trimethoprim–sulfamethoxazole A drug combination with broad-spectrum antibacterial activity against both gram-positive and gram-negative organisms. It is effective in the treatment of many infections, including pneumocystis pneumonia in aids. Chronic Granulomatous Disease
  • Nitrofurantoin
  • Cephalosporins Cephalosporins Cephalosporins are a group of bactericidal beta-lactam antibiotics (similar to penicillins) that exert their effects by preventing bacteria from producing their cell walls, ultimately leading to cell death. Cephalosporins are categorized by generation and all drug names begin with “cef-” or “ceph-.” Cephalosporins
  • Fluoroquinolone
• Correction of metabolic abnormalities
• Management of the underlying cause:
  • Nephrolithiasis Nephrolithiasis 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:
    • Alpha and calcium Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Electrolytes channel blockers (e.g., tamsulosin Tamsulosin A sulfonamide derivative and adrenergic alpha-1 receptor antagonist that is used to relieve symptoms of urinary obstruction caused by benign prostatic hyperplasia. Antiadrenergic Drugs, nifedipine Nifedipine A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure. Class 4 Antiarrhythmic Drugs (Calcium Channel Blockers))
    • Extracorporeal shockwave lithotripsy: High-energy shockwaves cause stones to fragment.
    • Percutaneous nephrolithotomy
    • Ureteroscopic or laparoscopic/open surgery
  • Benign Benign Fibroadenoma prostatic hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation:
    • α₁– receptor Receptor Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors blockers (e.g., tamsulosin Tamsulosin A sulfonamide derivative and adrenergic alpha-1 receptor antagonist that is used to relieve symptoms of urinary obstruction caused by benign prostatic hyperplasia. Antiadrenergic Drugs)
    • 5α-reductase inhibitors (e.g., finasteride Finasteride An orally active 3-oxo-5-alpha-steroid 4-dehydrogenase inhibitor. It is used as a surgical alternative for treatment of benign prostatic hyperplasia. Androgens and Antiandrogens)
  • Retroperitoneal Retroperitoneal Peritoneum: Anatomy fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans: corticosteroids Corticosteroids Chorioretinitis
  • Ureteropelvic junction Ureteropelvic junction Urinary Tract: Anatomy obstruction: pyeloplasty
  • Obstructing masses: consultation for surgical management (e.g., hysterectomy consult for an individual with large fibroid uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. 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. Uterus, Cervix, and Fallopian Tubes: Anatomy causing obstruction)
  • Malignancy Malignancy Hemothorax: chemotherapy Chemotherapy Osteosarcoma and/or 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 to reduce tumor Tumor Inflammation bulk in some malignancies (e.g., lymphoma Lymphoma A general term for various neoplastic diseases of the lymphoid tissue. Imaging of the Mediastinum)

Relief of obstruction

The goal is to decrease the pressure in the collecting system.

• Indications:
  • Complete obstruction
  • Presence of infection
  • Evidence of compromised renal function
• Lower urinary tract obstruction Urinary tract obstruction Urinary tract obstruction (UTO) refers to the blockage of the urinary tract, which can occur anywhere in the urinary tract. Urinary tract obstruction can be acute or chronic, partial or complete, and unilateral or bilateral. Urinary tract obstruction can cause acute or chronic kidney disease. Urinary Tract Obstruction:
  • Urethral catheterization
  • Suprapubic catheterization
• Upper urinary tract obstruction Urinary tract obstruction Urinary tract obstruction (UTO) refers to the blockage of the urinary tract, which can occur anywhere in the urinary tract. Urinary tract obstruction can be acute or chronic, partial or complete, and unilateral or bilateral. Urinary tract obstruction can cause acute or chronic kidney disease. Urinary Tract Obstruction:
  • Placement of retrograde ureteric stents
  • Percutaneous nephrostomy: subsequent antegrade stenting can be done.

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

• Chronic hydronephrosis causes ischemic injury, resulting in cortical and medullary atrophy Atrophy Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes. Cellular Adaptation, and permanent loss of renal function.
• Hydronephrosis is reversible if the obstruction is promptly relieved.