The natural history of neonatal vesicoureteral reflux associated with antenatal hydronephrosis

Purpose: In an attempt to evaluate the natural history of neonatal vesicour eteral reflux, patients with antenatal history of hydronephrosis and docume nted reflux in the first 30 days of life were analyzed. Materials and Methods: Between 1993 and 1998, 260 patients with a history o f antenatal hydronephrosis were referred for evaluation. Of these patients 31 were diagnosed with unilateral or bilateral refluxing renal units (54 re nal units). Patients were treated with a prospective plan of observational therapy and prophylactic antibiotics, and resolution rate was calculated in patients with adequate followup. Reflux grade was correlated with postnata l ultrasonographic findings, urinary tract infections and differential rena l function. Outcome analysis of 34 high grade (III to V) refluxing renal un its using the Kaplan-Meier survival curves was undertaken with the end poin t being complete resolution or improvement. Three patients with vesicostomy and 2 who underwent ureteral reimplantation were excluded from analysis. Results: Reflux was grade I in 5% (33% males), II in 15% (62% males), III i n 32% (71% males), IV in 18% (90% males) and V in 30% (100% males) of the p atients. Postnatal ultrasound findings correlated poorly with the presence and degree of vesicoureteral reflux. Of 17 patients followed for at least 1 4 months (average followup 20) there was complete resolution in 60% with gr ade III, 50% with grade IV and 28% with grade V reflux. Using the Kaplan-Me ier estimate there was a 50% chance of improvement (decrease in reflux grad e by at least 2 grades) in high grade reflux by age 16 months. Urinary trac t infections developed in 8 patients (26%) while on antibiotics. Of 46 rena l. units in 23 patients evaluated with a renal scan before urinary tract in fection, 12 had less than 35% function. Conclusions: A normal postnatal ultrasound should not be a basis for exclud ing the use of cystography. Our Kaplan-Meier estimate shows that high grade reflux does improve and may resolve spontaneously. In addition, renal scar ring may be seen with high and low grade reflux in the absence of urinary t ract infection but high grade reflux is associated with a higher incidence of infection.