Membranous Urethral Length as a Predictor for Urinary Incontinence After Holmium Enucleation of the Prostate for Benign Prostatic Hyperplasia - Beyond the Abstract
In this study, we investigated whether membranous urethral length (MUL), measured on preoperative prostate MRI, could serve as a predictor of postoperative SUI following HoLEP. MUL has been extensively studied in the context of radical prostatectomy, where longer preoperative MUL consistently predicts faster and more complete continence recovery. However, its role in BPH surgery - and particularly in HoLEP - has been far less explored.
Our findings demonstrate a robust and consistent association between longer MUL and lower odds of SUI at 1, 3, and 6 months after HoLEP. Importantly, this relationship persisted after adjustment for multiple clinical and perioperative factors, including age, body mass index, prostate volume, comorbidities, and operative duration. Each additional millimeter of MUL was associated with a clinically meaningful reduction in incontinence risk, and the predictive performance of the models improved over time, with excellent discrimination at 6 months (AUC 0.83).
From a mechanistic standpoint, these results are biologically plausible. Continence in men is largely dependent on the integrity of the external urethral sphincter, which is anatomically related to the membranous urethra. A longer MUL likely reflects a longer or more robust sphincteric segment, providing greater functional reserve and resistance to intraoperative traction, stretching, or partial injury during apical dissection. This is particularly relevant in HoLEP, where the wide range of endoscopic motion and apical manipulation may predispose to transient sphincter dysfunction.
One of the novel aspects of our work is the incorporation of internal validation and decision curve analysis. Beyond statistical significance, we sought to determine whether MUL-based models provide meaningful clinical utility. Decision curve analysis demonstrated a net benefit across a wide range of risk thresholds, suggesting that MUL could realistically be integrated into preoperative counseling frameworks. For example, patients with very short MUL may be counseled more explicitly regarding the likelihood of transient incontinence, offered early pelvic floor physiotherapy, or monitored more closely postoperatively.
Written by: Nick Lee, MD, Division of Urology, Department of Surgery, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada
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