Do infants with mild prenatal hydronephrosis benefit from screening for vesicoureteral reflux?

Screening for vesicoureteral reflux in asymptomatic infants with low grade hydronephrosis is unjustified if this condition is benign. We present a cohort with prenatally detected hydronephrosis, some observed without voiding cystourethrography, and compare outcomes to a classic, screened group.

A total of 206 consecutive children presenting with postnatally confirmed prenatally detected hydronephrosis (47% bilateral) were included in the study. Cases with associated renal or bladder anomalies were excluded. Children with low grade hydronephrosis either underwent screening voiding cystourethrography or did not, largely based on whether care was managed by a urologist or a nephrologist. Patients with high grade hydronephrosis routinely underwent voiding cystourethrography. Primary outcome was a symptomatic or febrile urinary tract infection. We used Mantel-Haenszel analysis to determine urinary tract infection risk factors during the first 2 years of life.

No urinary tract infection was observed in patients with grade I hydronephrosis. Urinary tract infections in low grade hydronephrosis were only seen in the voiding cystourethrogram group (7 patients), including 1 infection following voiding cystourethrogram. Urinary tract infection rate was 3.52 infections per 100 patient-years in children with low grade hydronephrosis and 11.1 infections per 100 patient-years in those with high grade hydronephrosis (p = 0.02). This increased risk of urinary tract infection in high grade hydronephrosis persisted after correcting for gender and circumcision status (IRR 3.17, p = 0.01). The association remained strong (IRR 2.48, 95% CI 0.96-6.44) but was not statistically significant (p = 0.053) after additionally correcting for vesicoureteral reflux status.

Our data suggest that children with low grade hydronephrosis and otherwise normal kidneys and bladder do not benefit from voiding cystourethrographic screening. Interestingly high grade hydronephrosis appears to carry a threefold greater risk of urinary tract infection compared to low grade hydronephrosis.