UTI. Pivotal studies are under way. Complications of reflux nephropathy are hypertension and chronic kidney disease(CKD). CKD is typically heralded by mild proteinuria andinvolves the development of focal and segmental glomerulosclerosis as well as interstitial scarring. Indications for surgical repair of VUR are controversial and have been mademore complex by the development of dextranomer/hyaluronic acid copolymer (Deflux procedure), which appears tobe a very successful minimally invasive correction of mild tomoderate VUR.
Anomalies of the urinary tract (UT) occur in up to 4% ofinfants. Bilateral renal agenesis occurs in 1 in 4000 births. Renal agenesis is a component of Potter syndrome (flatfacies, clubfoot, and pulmonary hypoplasia). Any intrauterine UT disorder that results in little fetal urine and, therefore, little amniotic fluid can lead to Potter syndrome.Unilateral renal agenesis occurs in 1 in 3000 births and is more common in infants of diabetic mothers and African Americans. It is accompanied by normal or minimallyreduced renal function. This condition can also be found with vesicoureteral reflux (VUR) and other anomalies of thegenital tract, ear, skeletal system, and cardiovascular system.Unilateral renal agenesis can be a component of the Turner syndrome, Poland syndrome, or VACTERL association (vertebral abnormalities, anal atresia, cardiac abnormalities, tracheoesophageal fistula, renal agenesis and dysplasia, andlimb defects).
Renal hypoplasia/dysplasia refers to kidneys that are congenitally small, malformed, or both. Over time many affected children progress to chronic kidney disease (CKD) because of reduced nephron number. The kidneys are often unable to fully reabsorb sodium and water, and these children require salt and water supplementation to optimize growth.
Multicystic renal dysplasia (MCD) is due to abnormalnephron development that occurs in 1 in 4000 births. Thereis minimal or no functioning renal tissue in the affected kidney; bilateral disease is lethal. There is an association withVUR in the contralateral kidney. MCD often spontaneouslyinvolutes over the first few years of life and is rarely associated with hypertension (HTN) or recurrent urinary tractinfection (UTI).
Polycystic kidney diseases (PKDs) are a group of genetic diseases affecting the kidneys and other tissues. PKD may be primary (autosomal recessive or autosomal dominant) or associated with other syndromes. Autosomal recessive PKD occurs in 1 in 10,000 to 40,000 children and is due to genetic defects in fibrocystin. Autosomal dominant PKD, due to defects in polycystin 1 or 2, occurs in 1 in 1000 individuals, making it the most common inherited kidney disease. Although there is some overlap clinically, the two conditions differ morphologically. Both may appear in infancy or in older children. Renal cysts also are observed in other inherited disorders, such as von Hippel–Lindau syndrome, tuberous sclerosis, and Bardet-Biedl syndrome.
Urinary tract obstruction can occur at any anatomiclevel of the genitourinary system (Table 168-1). Early in gestation, severe obstruction results in renal dysplasia. Ureteralobstruction later in fetal life or after birth results in dilation of the ureter and collecting system, often with subsequentrenal parenchymal alterations. An obstructed UT is susceptible to infections, which may worsen renal injury. Posterior urethral valves are the most common cause of bladder