Blake, C.H.; (2008) Exploring the non-invasive diagnosis of bladder outlet obstruction using a penile cuff. Doctoral thesis , University of London.

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Abstract

Introduction: It has been proposed that all men should undergo invasive pressure flow studies (PFS) prior to bladder outlet surgery. However, expense and morbidity limit the use of this investigation. A non-invasive technique for measuring bladder contractility using controlled inflation of a penile cuff has been developed. In work in an experimental model there is also evidence to suggest that this technique may be used to measure urethral opening pressure. The purpose of this thesis is to validate the penile cuff technique and to confirm whether this may used to diagnose bladder outlet obstruction (BOO) and obviate the need for invasive PFS prior to bladder outlet surgery. We also aim to elucidate whether cuff measurements can provide a non-invasive estimation of urethral opening pressure. Methods: 118 patients were investigated with free flow rates, invasive pressure flow studies, free cuff test, simultaneous cuff test and invasive PFS, and voiding urethral pressure profile (VUPP) measurements. Cuff pressure at flow interruption "pcuff.int" was compared with isovolumetric bladder pressure as a measure of bladder contractility. This was then used in conjunction with urinary flow rate to test a proposed non-invasive nomogram for diagnosis of bladder outlet obstruction. Cuff pressure at which flow rate starts to fall "pcuffknee", proposed as a measure of urethral opening pressure, was compared with estimations of urethral opening pressure taken from invasive pressure flow studies and VUPP's. Results: pcuff.int provides a valid estimation of isovolumetric bladder pressure. When used in combination with flow rate measurements this can be used to diagnose or exclude BOO in approximately two thirds of men, using a modification of the ICS nomogram. Although pcuff.knee does not correspond precisely with the previously described measures of urethral opening pressure, there is reasonable evidence to support our hypothesis that Pcuff knee may provide a simple and non-invasive estimation of urethral opening pressure.

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