Membranous urethral length on magnetic resonance imaging as a novel predictor of urinary continence after delayed anastomotic urethroplasty for pelvic fracture urethral injury

Purpose We studied the impact of membranous urethral length (MUL) on magnetic resonance imaging (MRI) on post-urethroplasty continence in male patients with pelvic fracture urethral injury (PFUI). Methods Of 169 male patients with PFUI who underwent delayed anastomotic urethroplasty between 2008 and 2020, 85 who underwent preoperative MRI, had no recurrent stenosis on cystoscopy, and underwent a 1-h pad test 1 year after surgery were included. MUL was defined as the distance from the distal end of the disrupted proximal urethra to the apex of the prostate, as measured using T2-weighted MRI. Urinary incontinence (UI) was defined as a 1-h pad test weight > 2.0 g. Results None of the patients had UI before a pelvic fracture. Eighty-two patients (96.5%) had a measurable MUL, and the median length was 8.1 (interquartile range [IQR], 5.2–10.8) mm. The median weight of the 1-h pad test was 1.0 (IQR, 0.0–4.0) g, and 26 (30.6%) patients had UI. An open bladder neck (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.0–22.0; p = 0.04) and a short measurable membranous urethra (for every extra mm: OR, 1.2; 95% CI, 1.0–1.3; p = 0.04) were significant UI predictors on multivariate analysis. Conclusions A long MUL is significantly positively associated with urinary continence in male patients with PFUI. This could be of potential value to reconstructive urologists when counseling patients regarding post-urethroplasty continence before urethroplasty.