Repeat Micturating Cystourethrogram After Ablation of Posterior Urethral Valves Fails to Predict Resection of Remnant Valve Leaflets on Subsequent Check Cystourethroscopy

Abstract

Purpose Judging the significance of valve remnants at check cystourethroscopy after ablation of posterior urethral valves (PUV) can be difficult. In November 2006, our Department adopted a policy of performing a repeat micturating cystourethrogram (MCUG) prior to check cystourethroscopy three months after primary PUV ablation. The aim of this study is to determine the predictive value of repeat MCUG for further valve resection at check cystourethroscopy. Material and Methods We retrospectively reviewed the operative notes and MCUG (performed by Consultant Paediatric Radiologists) of all 31 boys with PUV who had a check cystourethroscopy with pre-operative MCUG between November 2006 and October 2008. Results Repeat MCUG indicated remnant valves in ten boys, but no residual leaflets could be identified at subsequent endoscopy in four. In 21 boys, the PUV appeared completely ablated on MCUG. However, on cystourethroscopy, valve leaflets thought to necessitate resection were present in nine. Taking the degree of persistent posterior urethral dilatation on MCUG into consideration did not improve the test's ability to anticipate residual valve leaflets at check cystourethroscopy. The positive predictive value of repeat MCUG for subsequent resection of valve remnants is 60%; the negative predictive value is 57%. Conclusions Repeat MCUG after primary PUV ablation portends further resection of valve remnants at subsequent check cystourethroscopy in only 60%. Importantly, where complete PUV ablation is shown radiologically, remnant leaflets deemed significant are found on endoscopy in 43%. We recommend check cystourethroscopy three months after PUV ablation; pre-operative repeat MCUG is unprofitable.