Society for fetal urology recommendations for postnatal evaluation of prenatal hydronephrosis--will fewer voiding cystourethrograms lead to more urinary tract infections?

PURPOSE: There is no consensus on the extent and mode of postnatal imaging after a diagnosis of prenatal hydronephrosis. We validated the protocol of our practice, which parallels current Society for Fetal Urology (SFU) recommendations, in limiting voiding cystourethrogram, while examining its impact on the incidence of febrile urinary tract infections. A secondary goal was to examine predictors of postnatal intervention.

MATERIALS AND METHODS: We evaluated a cohort of 117 infants with prenatal hydronephrosis and retrospectively reviewed outcomes. Excluded from study were 30 infants with anatomical abnormalities. Third trimester prenatal ultrasound was done to evaluate SFU grade, laterality and anteroposterior diameter. Cox proportional hazard model and chi-square analysis were used to assess predictors of resolution and surgical intervention.

RESULTS: A total of 87 infants with a median followup of 33.5 months were included in analysis. Postnatal voiding cystourethrogram was done in 52 patients, of whom 7 had vesicoureteral reflux. In 6 infants (6.9%) a febrile urinary tract infection developed, which was diagnosed with a catheter specimen during followup. In 3 infants a urinary tract infection developed immediately after catheterization. Anteroposterior diameter 9 mm or greater and SFU grade 3 or greater independently predicted the need for postnatal intervention (p = 0.0014 and 0.001, respectively).

CONCLUSIONS: With adherence to our protocol, voiding cystourethrogram was avoided in almost half of evaluated infants. No infant diagnosed with vesicoureteral reflux had a urinary tract infection. Catheterization was associated with a urinary tract infection in 50% of cases. An anteroposterior diameter of 9 mm or greater and a SFU grade of 3 or greater were associated with postnatal progression to surgery. Patients with a SFU grade of 4 progressed to surgical intervention at a faster rate than those with a grade of greater than 3.