The current guidelines recommend several definitive treatments for prostate cancer, including radical prostatectomy, radiation therapy, and focal therapy such as High-Intensity Focus Ultrasound therapy(HIFU). Unfortunately, urinary incontinence is a common and distressing complication of these treatments. Many factors might contribute to post-prostatectomy incontinence (PPI), including age, length of the membranous urethra, prior history of transurethral resection of the prostate, preservation of neurovascular bundle and urethral length, vesicourethral reconstruction techniques, and sparing of Retzius space.[1] However, these pre-operative anatomical factors may change after surgery, and surgical techniques may not be a one-strategy-fits-all solution. 
The fundamental treatment of PPI is pelvic floor muscle training (PFMT). However, current evidence shows conflicting results regarding the different methods of PFMT.[2] One possible reason is the varied approach of PFMT in different studies, while other potential reasons include the severity of stress urinary incontinence and the co-existence of urge incontinence. While urodynamic studies can help differentiate the types of urinary incontinence after definitive treatment for prostate cancer, they are too invasive to be the first-line diagnostic tool. Therefore, developing a less invasive diagnostic tool for male urinary incontinence after definite therapy for prostate cancer is crucial for tailored PFMT. 
This study aims to use post-operative dynamic trans-rectal sonography to confirm the components and severity of stress urinary incontinence (SUI) in order to organize appropriate PFMT. This approach could be a less invasive diagnostic tool to tailor the treatment of urinary incontinence in patients who have undergone definitive treatments for prostate cancer, including radical prostatectomy and HIFU therapy.

Patients experiencing bothersome urinary incontinence after definitive treatment for prostate cancer were referred to our Uro-rehabilitation team for an intensive pelvic floor muscle training program. Consecutive patients were enrolled in this prospective clinical trial between January 2023 and March 2023. Dynamic trans-rectal sonography was used to evaluate the status of pelvic floor support and urethral competence during rest, cough, and strain phases. Other assessments included anal manometry and various pelvic floor functional parameters. The intensive pelvic floor training program involved six sessions of weekly vision-guided biofeedback and trans-anal electrical stimulation. The severity of urinary incontinence was measured using the International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF) questionnaire and the number of daily pads. Patient profiles were obtained through chart review.

During the study period, a total of ten patients completed six sessions of intensive PFMT. The patient characteristics are listed in Table 1. We categorized the ultrasound results into two components of stress urinary incontinence: the presence of intrinsic sphincteric deficiency (ISD) and the degrees of impaired pelvic floor support (see Fig. 1). The median age at definitive prostate therapy was 66 years (IQR 62-74), and the median time from prostate surgery to PFMT was 10 months (IQR 3-24 months). Eight patients received robotic radical prostatectomy, six using the conventional approach and two using the Retzius-sparing method, while the remaining two patients underwent HIFU therapy. 
The baseline median ICIQ-UI SF score was 19 (IQR 15-21), which improved to 16 (IQR 11-17) after PFMT. Digital rectal examination revealed a median improvement of 0.7 cm (IQR 0.5-0.8) in the length of the internal anal sphincter and a median improvement of 1 (IQR 0.5-0.7) in Oxford muscle power grading. Seven of the ten patients (70%) had a remarkable reduction of more than three pads daily. Anal manometry was used to quantify the contractility and endurance of the pelvic floor muscles. The median increment in maximum manometry was 17.1 mmHg (IQR 8.7-33.4 mmHg), while the median improvement in mean manometry was 3.2 mmHg (IQR 2.9-6.7 mmHg).

Of the seven patients who experienced a remarkable reduction in daily pad usage, three achieved complete continence without protective pads. Their baseline sonographic findings showed less intrinsic sphincteric deficiency (ISD) severity and impaired pelvic floor support. However, the remaining four patients still needed one to three pads daily after completing six sessions of intensive PFMT. The baseline dynamic trans-rectal ultrasound showed more severe ISD and pelvic floor hypermobility in these four patients, which helped predict the need for prolonged pelvic floor rehabilitation when patient counseling before initiation of intensive PFMT.
Among the three patients who continued using more than four pads daily, one still had severe ISD due to HIFU and salvage radiation therapy. The other two patients who still had severe PPI showed much improvement in ISD and pelvic floor support in dynamic sonography but had urge urinary incontinence (UUI). Video-urodynamic studies confirmed no more SUI but marked detrusor overactivity with UUI in these two patients, and further strategies for UUI were offered to them.

Post-prostatectomy and post-HIFU urinary incontinence are complex conditions that can be caused by intrinsic sphincteric deficiency, impaired pelvic floor support, and urge urinary incontinence. Dynamic trans-rectal sonography is a feasible and less invasive tool for identifying the specific components of PPI and providing valuable information for designing optimal continence programs.

Neurourol Urodyn. 2019;38 Suppl 5:S119-S126.
Cochrane Database Syst Rev. 2015;1(1):CD001843.