PEDIATRIC UROLOGY

doi: 10.1590/S1677-553820100003000028

Urinomas protect renal function in posterior urethral valves--a population based study
Wells JM, Mukerji S, Chandran H, Parashar K, McCarthy L
Department of Paediatric Urology, Birmingham Children’s Hospital, UK.
J Pediatr Surg. 2010; 45: 407-10

• Background/Purpose: Urinomas have been thought to protect renal function in boys with posterior urethral valves (PUVs), although recent reports have disputed this. This study tested the hypothesis that urinomas protect global renal function in boys with PUV.
  Methods: A retrospective analysis of all boys with PUV presenting to a tertiary unit derived from a region with an estimated population of 5.5 million was performed. Comparisons of the initial nadir creatinine, current creatinine, and renal status score (RSS) were made between those with and without urinomas. The RSS was derived from nephrology assessment of current renal status (0 = normal to 4 = end-stage renal failure or transplantation). Results were given as median (range), except for RSS, which was given as mean +/- SEM. P < or = .05 was regarded as significant.
  Results: During 1989-2009, 9 of 89 PUV boys were diagnosed with urinomas. Initial nadir creatinine was statistically lower in boys with urinomas (31 [18-44] vs 45 [20-574] mumol/L, P < .01). Length of follow-up was similar (5.1 [2.2-17.3] vs 5.9 [1.8-19.7] years, P = .59). Follow-up creatinine was significantly lower in urinoma boys (44 [25-77] vs 61 [29-1227] micromol/L, P < .05), as was the RSS (0.14 +/- 0.14 vs 0.91 +/- 0.14, P < .01). No urinoma boys progressed to end-stage renal failure or required transplant.
  Conclusion: This population-based study of PUV boys demonstrates that urinomas reduce nadir creatinine and significantly protect long-term global renal function.

• Editorial Comment
  The authors reviewed their data on all patients presenting with posterior urethral valves in infancy to their tertiary care center over 20 years. They identified 89 patients, 9 of whom were diagnosed with urinomas. Long term follow-up (mean of 5 years) in 7 of these patients showed that both initial nadir creatinine and follow-up creatinine were significantly lower in boys with urinomas. Renal status score was also significantly better in these boys and none has progressed to end stage renal failure or transplantation. Two of the 9 patients did not have long term follow-up due to their young age.
  Spontaneous decompression of the urinary tract in patients with posterior urethral valves has typically been thought to have a protective effect. As the authors point out, this notion has been challenged in the last decade. In response, this population based study is less likely to be tainted by selection bias seen in other reports and supports the hypothesis that decompression has a protective effect on renal function. Unfortunately, this hypothesis has not been uniformly supported by the use of vesicoamniotic shunting in the antenatal period. Perhaps this suggests that there are other factors which create a greater likelihood of spontaneous perforation that serve to protect long term renal function.

M. Chad Wallis
Division of Pediatric Urology
University of Utah
Salt Lake City, Utah, USA
E-mail: chad.wallis@hsc.utah.edu