Investigating The Mechanism Underlying Urinary Continence Using Dynamic-MRI After Retzius-sparing Robot-assisted Radical Prostatectomy

Abstract

Retzius-sparing robot-assisted radical prostatectomy (RS-RARP) has been reported to exhibit better postoperative urinary continence compared to conventional RARP (C-RARP) via the anterior approach, but the reasons behind this are unknown. The early postoperative urinary incontinence and anatomical differences were compared between 51 cases each of C-RARP and RS-RARP, which were selected via propensity score matching. Dynamic-MRI was performed before and after surgery to investigate the pelvic anatomical changes under abdominal pressure. The median urine loss ratio in the early postoperative period was 11.0% and 1.0% for C-RARP and RS-RARP, respectively. Postoperative MRI revealed the anterior bladder wall after RS-RARP was fixed in a high position compared to C-RARP. Dynamic-MRI after C-RARP showed cephalocaudal compression of the bladder during abdominal pressure caused expansion of the membranous urethra and the urine flowed out. In RS-RARP cases, the rectum moved forward during abdominal pressure to compress the membranous urethra by closing it from behind, as was observed preoperatively. This was the first study using dynamic-MRI which revealed the importance of a high attachment of the anterior bladder wall for the urethral closure mechanism during abdominal pressure. RS-RARP, which can completely preserve this mechanism, was the least likely to cause stress urinary incontinence.

Simultaneous robot‐assisted abdominoperineal rectal resection and Retzius‐sparing prostatectomy for synchronous rectal and prostate cancer – a video vignette

“…As proctectomy increases the risk of surgical complications (urinary peritonitis) and also predisposes the patient to possible functional sequelae (urinary incontinence) due to the absence of posterior anatomical structures, a Retzius-sparing approach was selected. This technique is technically more demanding but it enables preservation of the anterior anatomical structures, especially the detrusor apron, which, according to published reports, leads to the early recovery of continence [5]. The prostate was removed in a retrieval laparoscopic bag and a permanent colostomy was constructed at the end.…”