Post-prostatectomy urinary incontinence (PPI) can occur following radical prostatectomy despite advances in surgical techniques such as nerve-sparing procedures and robotic-assistance. PPI is a debilitating complication of prostatectomy surgery which significantly impacts the patient’s quality of life. The incidence of post-prostatectomy incontinence (PPI) following robotic assisted procedures is estimated at 5-20% at 12 months (1). 

PPI can result from intrinsic sphincter deficiency (ISD) and/or bladder dysfunction. PPI is commonly attributed to ISD based on patient’s symptoms correlating with stress urinary incontinence (SUI). Bladder dysfunction resulting from reduced compliance and/or detrusor overactivity (DO) can impact the success of stress incontinence surgery. Furthermore, artificial urinary sphincter (AUS) or sling procedures increase outlet resistance and therefore increase leak point pressures. If reduced compliance and/or DO is present, higher amplitude and more sustained detrusor pressures can occur as a result, increasing the risk of renal dysfunction. Despite the ability of urodynamics to fully characterise bladder function, there is not a consensus whether urodynamic should be performed before treating the stress component of PPI nor is it explicitly recommended in any of the major guidelines.  

The aim of our retrospective study was to identify the prevalence of bladder dysfunction in post-prostatectomy patients who underwent urodynamic studies.

We retrospectively reviewed urodynamic studies of 84 patients reporting lower urinary tract symptoms (LUTS) who had underwent prostatectomy. Exclusion criteria included patients with known neurological diagnosis. 

All urodynamic studies were conducted in accordance with the ICS good Urodynamics Practice document. Urodynamic parameters analysed included the presence of detrusor over activity (DO), the peak pressure of DO (DO PP),  bladder compliance, maximum cystometric capacity (MCC), the cause(s) of urinary incontinence, voided volume, maximum detrusor pressure during voiding (max.Pdet), maximum flow rate (Qmax), detrusor pressure at maximum flow (Pdet.Qmax), post void residual (PVR) and bladder outlet obstruction index (BOOI). Unpaired t-tests and Mann Whitney tests were used to compare parametric and non-parametric variables between external beam radiotherapy (EBRT) and non-EBRT groups respectively. 

If persistent urinary leakage occurred in the absence of sensation and raised detrusor pressure, the urethra was occluded using a penile cuff, allowing the faithful assessment of bladder filling parameters. Urethral occlusion was removed when the patient experienced a strong desire to void.

The age range was aged between 48-84 years (median 67). The primary presenting symptom for each patient is displayed in figure 1. 

Table 2 details the UDS parameters, comparing patients with and without EBRT. 58 (69%) of patients had SUI reproduced during UDS. The mean (±SD) MCC was 362(±177) ml. 52 (62%) of patients demonstrated DO during UDS, with a mean (±SD) peak pressure of 27(±30) cmH2O. 25 (30%) of patients had high pressure DO (>40cmH2O). The mean (±SD) bladder compliance was 99 (±101) ml/cmH2O with 18 (21%) patients having a compliance value <40ml/cmH2O. 

19/84 patients had previous pelvic EBRT. There was no statistical difference between the prevalence of DO in non-EBRT and EBRT groups, 62% and 61% respectively (p = 0.95). Nor was there a statistical difference in DO PP with non-EBRT and EBRT groups of 28 (±32) cmH2O and 23 (±22) cmH2O respectively (p = 0.54). The EBRT group had a mean compliance of 68 (±70) ml/cmH2O with 8 (44%) patients having reduced compliance (<40ml/cmH2O), compared to the non-EBRT group’s mean of 107 (±106) ml/cmH2O and 10 patients having reduced compliance (15%) (p = 0.14 and p = 0.06 respectively). There was no statistical difference in voided volume, Qmax or PVR (0.457, 0.426 and 0.901 respectively). The EBRT group did have statistically higher maximum detrusor pressures during voiding with a mean of 40 (±24) cmH2O compared to the non-EBRT group of 28 (±17) cmH2O (p = 0.02).

50% of patients reported UUI (either primary UUI or MUI) prior to UDS. 62% of prostatectomy patients demonstrated DO during UDS with 21% demonstrating reduced compliance (<40ml/cmH2O). 

Any DO PP >32cmH2O is likely to result in persistent UI post incontinence surgery, as average abdominal pressure is ~38cmH2O (2) and ALPP of artificial urinary sphincter’s is ~70cmH2O (3). 30% of patients in our study had DO PP >40cmH2O. It is also worth noting that DO PP and compliance values are likely under and overestimated respectively during UDS due to low leak point pressures as a result of ISD (present in 69% of patients).

There was no statistical difference in the prevalence or pressure of DO between EBRT and non-EBRT groups. The prevalence of reduced compliance was increased in the EBRT group and neared statistical significance (p = 0.06). The EBRT group also had statistically higher Pdet.Qmax (p = 0.02). This increase may be due to inflammatory changes in the urethra rather than more contractile detrusor as the mean DO PP and prevalence of DO were similar in the two groups. These results indicate non-EBRT patients also demonstrate similarly high levels of bladder dysfunction following prostatectomy.

This high proportion of bladder dysfunction demonstrated during UDS confirms its utility as a prognostic test in predicting continence success and potentially the deterioration of renal function.

Almost 2/3 and 1/5 of patients with PPI demonstrated DO and reduced compliance respectively. The two factors are likely to mean treating the outlet dysfunction alone is unlikely to cure the incontinence but more likely worsen the filling phase LUTS. Therefore, UDS, with urethral occlusion where necessary should be performed before treating the ISD to fully characterise the bladder dysfunction and the prognostic information used to fully inform the patient before treating the stress component of PPI.

Toia B, Leung LY, Saigal R, et al. Is pre-operative urodynamic bladder function the true predictor of outcome of male sling for post prostatectomy incontinence? World Journal of Urology. 2020;39(4):1227-1232. doi:10.1007/s00345-020-03288-8
McIntosh S, Drinnan M, Griffiths C, Robson W, Ramsden P, Pickard R. Relationship of abdominal pressure and body mass index in men with LUTS. Neurourol Urodyn. 2003;22:602–605.
Solomon E, Veeratterapillay R, Malde S, Harding C, Greenwell TJ. Can filling phase urodynamic parameters predict the success of the bulbar artificial urinary sphincter in treating post-prostatectomy incontinence?. Neurourol Urodyn. 2017;36(6):1557-1563. doi:10.1002/nau.23147