Simplified diagnostic algorithm for evaluation of neonates with prenatally detected hydronephrosis

The management of neonates with congenital hydronephrosis (CHN) diagnosed antenatally is still controversial.

A prospective study was performed in all newborn infants with CHN born over a 2-year period in order to identify which neonates require a full radiologic investigation including investigation with invasive tests such as voiding cystoureterography (VCUG) and diuretic-enhanced renography. Data on kidney ultrasonography, VCUG, and diuretic renography were collected. The ultrasound grading of hydronephrosis was determined according to Society of Fetal Urology criteria.

Sixty-one neonates (47 boys and 14 girls) with CHN were enrolled. All underwent kidney ultrasonography within 72 to 96 hours after birth. Four (7%) had no residual CHN, 34 (56%) had and 23 (38%) unilateral CHN. Of the 41 newborns exposed to diuretic renography, 18 (44%) had ureteropelvic junction obstruction (UPJO). Of the 34 infants that underwent VCUG, 8 (24%) had vesicoureteral reflux (7 bilateral grade 2 or higher, 1 unilateral grade 1 CHN SFU classification). None of the unilateral grade 1 or 2 CHN due to UPJO had vesicoureteral reflux and none with vesicoureteral reflux had UPJO. Twelve patients required surgery (7 had UPJO and 3 high-grade vesicoureteral reflux).

These data suggest that mild to moderate unilateral or bilateral CHN rarely coexists with severe obstruction or vesicoureteral reflux. Therefore, systemic VCUG and renography in such patients do not seem justified. Postnatal ultrasonography in combination with renography and VCUG is warranted in the routine examination of neonates presenting with severe unilateral or bilateral CHN.