Posterior urethral valves: relationship between vesicoureteral reflux and renal function

To investigate the relationship between renal function and vesicoureteral reflux before and after valve ablation in patients with posterior urethral valves. In these patients, back pressure may not be the only cause of renal damage.

We conducted a retrospective review of 37 patients with valves consecutively treated between 1970 and 2002. Data were available for 31 patients, 19 of whom presented reflux at presentation. Grade of reflux was ascertained by voiding cystourethrography. Overall renal function was measured by serum creatinine, and split renal function was estimated by dimercaptosuccinic acid scan available for all patients but two.

Before relief of obstruction, there was no correlation between split renal function and grade of reflux into 25 kidneys of the 17 patients (r = -.13; 95% CI, -.50 to .27; P = .51). High-grade reflux (grade IV-V) affected 6 of the 11 renal units, with split renal function >40% vs 11 of the 14 units with split renal function <40% (P = .38). After successful valve ablation, reflux resolved in all the 11 units with split renal function >40% vs 4 of the 14 units with split renal function <40% (P = .0005).

The good renal function of more than half of the renal units with high-grade reflux at presentation, and the persistence of reflux mainly in nonfunctioning or poorly functioning kidneys after valve ablation, support the concept that in some patients with valves, reflux and renal damage are associated anomalies.