Minimal residual membranous urethral length and membranous urethral length predict poor recovery from incontinence after robot-assisted radical prostatectomy and after open radical prostatectomy.

Objectives: To investigate how much minimal residual membranous urethral length (mRUL) and maximal urethral length (MUL) measured on MRI preoperatively affect postoperative urinary incontinence (PUI) and recovery in robot-assisted radical prostatectomy (RARP) and open radical prostatectomy (ORP).
Methods: The subjects were 190 and 110 patients undergoing RARP and ORP, respectively, in our institution. Patients underwent preoperative MRI for prostate cancer evaluation and completed the quality of life questionnaire of the Expanded Prostate Cancer Index Composite instrument before and 1, 3, 6, and 12 months after surgery. The parameters of mRUL and MUL were measured on MRI and analyzed along with other parameters including age, body mass index, and nerve sparing.
Results: The median mRUL and MUL were 7.81 and 14.27 mm in the RARP group and 7.15 and 13.57 mm in the ORP group, respectively. Recovery rates from PUI were similar in the two groups. Multivariate analyses showed that mRUL was a predictor of baseline continence, whereas shorter MUL was a predictor of poor recovery from PUI. Patients with both shorter mRUL and MUL had significantly worse recoveries from PUI after RARP and ORP than patients with longer mRUL and MUL.
Conclusions: Minimal residual membranous urethral length contributes to urethral function as basal urinary continence, whereas MUL represents the potential of recovery from PUI in RARP and ORP. The MUL measured by preoperative MRI can predict poor recovery from PUI after radical prostatectomy and combined evaluation of MUL and mRUL support to anticipate poor recovery of PUI.
(© 2022 The Japanese Urological Association.)