The natural history of neonatal vesicoureteral reflux associated with antenatal hydronephrosis

In an attempt to evaluate the natural history of neonatal vesicoureteral reflux, patients with antenatal history of hydronephrosis and documented reflux in the first 30 days of life were analyzed.

Between 1993 and 1998, 260 patients with a history of antenatal hydronephrosis were referred for evaluation. Of these patients 31 were diagnosed with unilateral or bilateral refluxing renal units (54 renal 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 postnatal ultrasonographic findings, urinary tract infections and differential renal function. Outcome analysis of 34 high grade (III to V) refluxing renal units using the Kaplan-Meier survival curves was undertaken with the end point being complete resolution or improvement. Three patients with vesicostomy and 2 who underwent ureteral reimplantation were excluded from analysis.

Reflux was grade I in 5% (33% males), II in 15% (62% males), III in 32% (71% males), IV in 18% (90% males) and V in 30% (100% males) of the patients. Postnatal ultrasound findings correlated poorly with the presence and degree of vesicoureteral reflux. Of 17 patients followed for at least 14 months (average followup 20) there was complete resolution in 60% with grade III, 50% with grade IV and 28% with grade V reflux. Using the Kaplan-Meier estimate there was a 50% chance of improvement (decrease in reflux grade by at least 2 grades) in high grade reflux by age 16 months. Urinary tract infections developed in 8 patients (26%) while on antibiotics. Of 46 renal units in 23 patients evaluated with a renal scan before urinary tract infection, 12 had less than 35% function.

A normal postnatal ultrasound should not be a basis for excluding the use of cystography. Our Kaplan-Meier estimate shows that high grade reflux does improve and may resolve spontaneously. In addition, renal scarring may be seen with high and low grade reflux in the absence of urinary tract infection but high grade reflux is associated with a higher incidence of infection.