Post-prostatectomy incontinence (PPI) is common but the underlying mechanisms are not well-understood. There has been recent suggestion that dynamic pelvic floor muscle (PFM) mobility as seen on transperineal ultrasound (TPUS) may predict PPI [1]. We investigated the longitudinal relationship between PPI and PFM mobility pre-operatively and at three and six weeks post-operatively.

This is an original prospective study of 40 patients who underwent robotic-assisted radical prostatectomy (RARP) between February and November 2019 by a single surgeon at a high volume robotic centre. Patients completed a 24-hour pad test, assessing pad weight and number, and underwent a transperineal ultrasound (TPUS) to record sagittal images of pelvic structures during maximal voluntary PFM contraction pre-operatively and at post-operative three and six weeks. TPUS images were analysed using InteleViewer software to calculate displacement of striated urethral sphincter, bulbocavernosus and puborectalis muscles. PFM mobility was analysed to determine whether mobility differs between men who are continent and incontinent.

There was significant correlation between pre-operative and post-operative PFM mobility (p<.05). With continence defined as use of ≤1 pad daily, which was 70% and 95% of patients at three and six weeks, respectively. There is significantly more SUS mobility at post-operative three weeks in continent men (median=5.13mm) compared to incontinent men (median=3.90mm), p=.029. Whilst the median mobility at post-operative three weeks for BC and PR was greater in continent men than incontinent men, this did not reach statistical significance (p=.13, p=.59, respectively).

This study evaluated the longitudinal relationship between pre- and post-operative dynamic PFM mobility and PPI using objective outcome measures of pad number. We showed that there is significantly more SUS mobility in continent men compared to incontinent men at post-operative three weeks. Investigation of dynamic PFM mobility is a novel area of inquiry and to our knowledge, there is no longitudinal data on dynamic PFM mobility pre- and post-prostatectomy. Only one previous cross-sectional study has evaluated the activation of SUS, BC and PR [1]. Stafford et al. analysed which combinations of pelvic anatomy variables, including activation of SUS, BC and PR, functional urethral length and resting position of the anorectal and urethrovesical junctions, best distinguished between men with and without PPI [1]. They observed that greater SUS displacement was associated with continence and was able to compensate for poor BC and PR function and vice versa, to a lesser extent. Our results are in keeping with Stafford et al.’s paper, however, we used a more robust study design with longitudinal data, greater consistency of control variables and more reliable outcome measures.

Pelvic floor muscle mobility of SUS may be a reliable independent predictor of PPI. Mechanisms of continence control remain poorly understood and further research is warranted.

Stafford R, van den Hoorn W, Coughlin G, Hodges P. Postprostatectomy incontinence is related to pelvic floor displacements observed with trans-perineal ultrasound imaging. Neurourology and Urodynamics. 2017;37(2):658-665.

Continence 2S2 (2022) 100409
DOI: 10.1016/j.cont.2022.100409