Re-ablation of residual posterior urethral valves: a single-centre retrospective review

Abstract

Background: Residual posterior urethral valves (RPUV) after primary ablation can be responsible for the persistence of urinary symptoms and worsening of renal function in children. This study aims to determine the impact of repeat cystoscopy and subsequent re-ablation of RPUV using changes in serum creatinine and ultrasonographic renal pelvic diameter (RPD).

Methods: A retrospective review of 85 patients with posterior urethral valves (PUV) was conducted. Serial serum creatinine measurements (umol/L) and ultrasonographic RPD measurements (mm) were retrieved and recorded on three separate, dated occasions against the date of surgery as follows: M1: before primary valve ablation; M2: before repeat cystoscopy; and M3: after repeat cystoscopy. The changing trends in both the serum creatinine and the RPD were analysed for significance against time.

Results: The median age at primary valve ablation was seven weeks (IQR [interquartile range] 2.75–91.45). Repeat cystoscopy was performed in 94.7% of patients, detecting a 77.1% prevalence of residual valves. The initial mean creatinine before primary ablation was 150.8 umol/L, with 75% of patients having elevated creatinine levels before surgery. The serum creatinine showed a significant improvement after primary ablation (mean: M1: 150.8 umol/L to M2: 42.1 umol/L, p = 0.0001) but minimal improvement after re-ablation (M2: 42.1 umol/L to M3: 39.2 umol/L, p = 0.68). There was more dilatation in the left renal units (mean: M1: 13.4 mm, M2: 10.9 mm, M3: 8.3 mm) compared to the right (mean: M1: 11.9 mm, M2: 9.7 mm, M3: 8.5 mm). The left RPD showed significant improvement after both primary ablation (p = 0.04) and re-ablation (p = 0.04). Similarly, the right RPD showed improvement on both occasions, albeit not statistically significant (p = 0.14 and p = 0.29, respectively).

Conclusion: The prevalence of RPUV after primary ablation was 77%, with an improvement in the trend of hydronephrosis and serum creatinine after re-ablation of residual valves. Repeat cystoscopy is therefore effective in the detection of residual valves and has the added benefit of being both diagnostic and therapeutic.