Infundibula/pelvis Congenital, calculi, infection, trauma/ hemorrhage, tumor Ureteropelvic Congenital stenosis,* calculi, trauma/ junction hemorrhage
Ureter Obstructive megaureter,* ectopic ureter, ureterocele, calculi,* inflammatory bowel disease
Retroperitoneal tumor (lymphoma), retroperitoneal fibrosis, chronic granulomatous disease
Bladder Neurogenic dysfunction,* tumor (rhabdomyosarcoma), diverticula, ectopic ureter
Urethra Posterior valves,* diverticula, strictures, atresia, ectopic ureter, foreign body, phimosis,* priapism *Relatively common.
outlet obstruction in males, present in 1 in 50,000 boys.Parents may note a poor urine stream in affected children.The valves are sail-shaped membranes that arise from the verumontanum and attach to the urethral wall. The prostaticurethra becomes dilated, VUR may be present, and hypertrophied detrusor muscle develops. Renal dilation variesin severity. Some degree of renal dysplasia is often present.Severe obstruction may be associated with oligohydramnios, resulting in lethal pulmonary hypoplasia. Intrauterinerupture of the renal pelvis produces urinary ascites, which is the most common cause of ascites in the newborn period.
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Bilateral renal agenesis results in insufficient lung development and Potter syndrome. Respiratory distress is severe, pneumothoraces can occur, and severe pulmonary hypoplasia is fatal. Unilateral renal agenesis may be asymptomatic because the nonaffected kidney undergoes compensatory growth and provides normal renal function.
Autosomal recessive PKD is characterized by marked bilateral renal enlargement. Interstitial fibrosis and tubular atrophy progress over time. Kidney failure usually occurs in early childhood. Hepatic fibrosis is present and may lead to portal HTN. Bile duct ectasia and biliary dysgenesis occur. Many affected infants display flank masses, hepatomegaly, pneumothorax, proteinuria, and/or hematuria.
Autosomal dominant PKD typically presents in middle adulthood but may present in infancy or childhood. Infants may have a clinical picture similar to autosomal recessive PKD, but older children show a pattern similar to that of adults, with large isolated cysts developing over time. The defect may occur anywhere along the nephron unit. Hepatic cysts are often present, and pancreatic, splenic, and ovarian cysts can also develop. Cerebral aneurysms may develop, and the risk of hemorrhage depends on size, blood pressure, and family history of intracranial hemorrhage.
UT obstruction may be silent but usually is discovered during prenatal ultrasound or with UTI or flank mass in early childhood. In a newborn, the most common type of abdominal mass is renal (most commonly ureteropelvic junction obstruction).
Renal ultrasound (RUS) and radionuclide renography(usually with a diuretic administered) are the standard testsfor diagnosis of UT obstruction. RUS allows identificationof renal agenesis, hypoplasia, dysplasia, cysts, and UT dilation. Obstruction may be suggested but a dilated UT mayalso result from VUR, ureteral hypoplasia, or neurogenicbladder. A voiding cystourethrogram (VCUG) is also apart of the evaluation. Many boys with posterior urethralvalves are identified by prenatal ultrasound. Postnatally the diagnosis and extent of renal damage are established by RUSand VCUG.