Urinary continence after radical retropubic prostatectomy: Relationship with membranous urethral length on preoperative endorectal magnetic resonance imaging

Purpose: We determined whether membranous urethral length on preoperative magnetic resonance imaging (MRI) is predictive of urinary continence after radical retropubic prostatectomy. Materials and Methods: Membranous urethral length was measured on preoperative endorectal MRI in 211 consecutive patients with newly diagnosed prostate cancer before radical retropubic prostatectomy performed by a single surgeon. Neurovascular bundle resection was done in 60 cases. After surgery the time to stable postoperative continence was recorded in 180 cases and the level of stable continence was graded on a 5-point scale of 1-complete continence to 5-complete incontinence. Results: After controlling for age and surgical technique multivariate analysis showed that membranous urethral length was related to time to stable postoperative continence (p = 0.02), such that a longer membranous urethra was associated with a shorter time to stable continence. For example, 1 year after surgery 120 of the 134 patients (89%) with a preoperative membranous urethral length of greater than 12 mm. were completely continent compared with 35 of the 46 (77%) with a preoperative length of 12 mm. or less. Conclusions: On endorectal MRI before radical prostatectomy a longer membranous urethra is associated with significantly more rapid return of urinary continence after surgery.