The effect of preoperative membranous urethral length on likelihood of postoperative urinary incontinence after robot-assisted radical prostatectomy

Urinary incontinence after radical prostatectomy affects many men. In addition to surgical and patient factors, longer preoperative membranous urethral length (MUL) has been suggested to be associated with improved postoperative urinary continence outcomes. Here, we assess the association of preoperative MUL and the risk of persistent postoperative urinary incontinence after robot-assisted radical prostatectomy (RARP) for prostate cancer on extended follow-up.All participants underwent RARP at the University of California, San Francisco between 2000-2018. Patients were excluded if preoperative MRI-measured MUL was not performed by a radiologist. A single, blinded urologist remeasured MUL retrospectively. Logistic regression models examined associations between radiologist- and urologist-measured MUL and likelihood of persistent incontinence post-RARP by two definitions: strict incontinence (>0 pad/day) and social incontinence (>1 pad/day).In 251 men with a median follow-up of 42 months (IQR 29-76), the median MUL measurements were 14 mm ([IQR 12-17], radiologist) and 15 mm ([IQR 12-18], urologist) with poor agreement (interclass correlation coefficient 0.34). On logistic regression, urologist-measured longer MUL was associated with lower likelihood of strict incontinence within 6 months (odds ratio [OR] 0.87; 95% confidence interval [CI] 0.81-0.94) and 12 months (OR 0.90; 95% CI 0.82-0.98) and social incontinence within 6 months (OR 0.93; 95% CI 0.86-1.00) and 12 months (OR 0.84; 95% CI 0.74-0.95). Radiologist-measured longer MUL was associated with lower likelihood of strict incontinence within 6 months (OR 0.93; 95% CI 0.87-1.00) and social within 12 months (OR 0.87; 95% CI 0.77-1.00). MUL was not associated with likelihood of strict or social incontinence within 24 months.Preoperative MRI-measured MUL was not associated with urinary incontinence after 12 months post-RARP. Poor agreement between radiologists' and urologist's measurements supports standardizing MUL measurements to establish the likelihood of early incontinence.