Congenital, Hereditary, Urologic, and Developmental Renal Disorders
Core concepts
Congenital and hereditary renal disorders include CAKUT, vesicoureteral reflux, obstruction, cystic diseases, and hereditary nephropathies. Posterior urethral valves occur in males and can cause bilateral hydronephrosis, thickened bladder, weak stream, and oligohydramnios; immediate bladder drainage is essential. Ureteropelvic junction obstruction causes hydronephrosis without reflux. Multicystic dysplastic kidney is usually unilateral and nonfunctioning. Autosomal recessive polycystic kidney disease presents in infancy with enlarged cystic kidneys, hypertension, and liver fibrosis; autosomal dominant polycystic kidney disease often presents in adulthood. Alport syndrome causes hematuria, hearing loss, and ocular abnormalities. Nephronophthisis causes polyuria, growth failure, and progression to CKD.
Traps
Bilateral hydronephrosis in a male neonate is posterior urethral valves until proven otherwise; place a catheter and obtain a voiding cystourethrogram. Do not perform a VCUG during acute infection if it can be deferred. Not all antenatal hydronephrosis requires surgery; grade and monitor. Distinguish reflux from obstruction. Recognize that unilateral multicystic dysplastic kidney usually has a good prognosis but requires monitoring of the contralateral kidney and blood pressure.
Worked example / rule of thumb
A newborn boy with a palpable bladder, weak urinary stream, and bilateral hydronephrosis has posterior urethral valves. Place a urethral catheter urgently and arrange VCUG and urology consultation. Rule: bilateral hydronephrosis in a male infant equals PUV until excluded.