URINARY DIVERSION IN BOYS WITH PUV-IS IT JUST A WET PATCH?

Introduction

Posterior urethral valves (PUV) are the most common cause of obstructive uropathy in children and an important cause of chronic disease (CKD). The CKD is attributed to associated renal dysplasia, hypertension, bladder dysfunction, proteinuria, episodes of recurrent urinary tract infections (UTI) and acute kidney injury (AKI). After valve incision and/or diversion, these boys require lifelong monitoring of bladder dynamics and of renal function by a pediatric urologist/ surgeon and a pediatric nephrologist followed by careful transition to adult care. 

Current state of the art laser equipment allows incision of valves even in very small neonates. Literature regarding urinary diversion in the form of ureterostomies as management is highly controversial. We present our experience from a Pediatric Nephrology Service at a tertiary care hospital of a low-income health care system, where the initial surgical management is performed by a pediatric surgeon and the rest by pediatric nephrologists.

We compared the outcome of boys with PUV and dilating reflux who had undergone urinary diversion with those who had undergone only valve incision with respect to progression to chronic kidney disease stage 4 or more.

In this retrospective chart review we included all cases of PUV diagnosed by voiding cystourethrogram and or cystoscopy who had been managed in this hospital and followed up for at least 5 years. A note was made of anthropometry, serial renal function tests, findings of ultrasonograms (USG), micturating cystograms and dimercaptosuccinic acid radionuclide (DMSA) scans. Glomerular filtration rate was calculated by the bedside modified Schwartz formula. The details of bladder evaluation and surgical procedures were noted.

Continuous data has been presented as mean ± SD, or median and interquartile ranges and compared by using the t test or Mann Whitney U test respectively. Categorical variables have been presented as proportions and compared using the chi-square test. A p value of less than 0.05 was considered statistically significant.

Of the 310 patients with PUV registered in the clinic, 100 had a follow up of 5 years’ duration; of these 48 demonstrated dilating vesicoureteric reflux (grades III - V); 31 had undergone diversion (23 ureterostomies [unilateral or bilateral]), 3 ureterostomies and vesicostomy, 3 vesicostomies and 2 nephrostomies). The median age of performing the diversion was 2 months (IQR 0.9-5) and closed at last follow-up in 90% (28/31) children at median age 26.7 (IQR 7- 42 ) months.

A similar proportion of children from the 2 groups developed CKD stage 4 or more (Table). The  children who had a diversion were diagnosed with PUV earlier than those who did not. The children in both the groups  were similar with respect to the  presence of hypodysplasia on USG, abnormalities on DMSA scan, duration of follow up post diagnosis, age and growth parameters at last follow up. They showed no difference in  requirement of clean intermittent catheterization and/or overnight drainage of the bladder.

Table: Comparison of parameters of children with PUV and dilating reflux with and without a diversion

In boys with posterior urethral valves creation of urinary diversion does not seem to affect progression to CKD stage 4, 5.