Integrity of the Urethral Sphincter Complex, Nerve-sparing, and Long-term Continence Status after Robotic-assisted Radical Prostatectomy

Abstract

BackgroundThe applicability of the sphincter complex integral theory to robotic-assisted radical prostatectomy (RARP) is unclear, with little known about the long-term effect of sphincter complex integrity on continence. ObjectiveTo determine whether the preoperative anatomical and functional features of the sphincter complex and the degree of nerve-sparing affect long-term continence after RARP. Design, setting, and participantsProspective study of 529 patients who underwent RARP at a single tertiary center. Outcome measurements and statistical analysisAnatomical factors, including membranous urethral length (MUL) and pelvic diaphragm length (PDL), were assessed using sagittal views of preoperative magnetic resonance imaging. MUL was defined as the distance from the posterior prostate apex to the urethra level at the penile bulb, and PDL was defined as the length of the urethra that met the planes created by the pelvic floor muscles. Functional parameters including maximum urethral closure pressure (MUCP) and functional urethral length were evaluated using preoperative measurements of the urethral pressure profiles. The degree of nerve-sparing was stratified as bilateral, unilateral, or none. Continence (pad-free status) was assessed according to anatomical and functional factors and nerve-sparing. We used binary logistic regression to assess factors predicting continence return 12 mo after RARP. Results and limitationsContinence return rates 1, 3, 6, and 12 mo after RARP were 39.7%, 66.0%, 80.2%, and 87.0%, respectively. Continence return rates at 12 mo differed significantly in patients with MUL ≥11.7mm (91.9%) and <11.7mm (79.9%), PDL ≥9.9mm (96.7%) and <9.9mm (74.5%), and MUCP ≥66 cmH2O (89.7%) and <66 cmH2O (79.4%). The continence return rate was significantly higher in patients with bilateral (93.0%) than in patients with unilateral (78.1%) or no (76.7%) nerve-sparing. Multivariate analysis showed that PDL (odds ratio [OR]=2.187 per mm), MUCP (OR=1.037 per cmH2O), and bilateral nerve-sparing (OR=3.671) were independently associated with continence return 12 mo after RALP. ConclusionsThe anatomical length and static pressure of the sphincter complex affected continence after RARP. Bilateral nerve-sparing was independently associated with long-term continence. Patient summaryPredisposing length and static pressure of the urinary sphincter affect continence after robotic-assisted radical prostatectomy. Nerve bundle preservation during surgery enhances postoperative return of continence.