Pre-prostatectomy membranous urethral length as a predictive factor of post prostatectomy incontinence requiring surgical intervention with an artificial urinary sphincter or a male sling

Aims: To ascertain whether the membranous urethral length (MUL) is predictive of postprostatectomy incontinence (PPI) that requires surgery such as artificial urinary sphincter (AUS) or male sling (MS).

Methods: Men who had undergone AUS or MS for PPI were identified from a prospectively maintained database and compared to a control group of men who were continent at 12 months after radical prostatectomy. MUL in sagittal and coronal planes, sphincter height and width were measured on prebiopsy T2-weighted MRI scans. Sphincter volume was estimated as an ellipsoid cylinder.

Results: A total of 95 patients (64 AUS and 31 MS) were compared to 60 continent controls. There was no statistical difference in presenting PSA, prostate volume, and T-stage. The mean MUL in sagittal and coronal planes was 11.31 mm (SD: 2.6, range: 6-17 mm) and 11.43 mm (SD: 2.94, range: 5-17 mm) in patients who had AUS and MS, respectively; 15.23 mm (SD: 4.2, range: 8.25-25 mm) and 15.75 mm (SD: 4.1, range: 8-24 mm) in controls (p < 0.01). No men in the PPI surgery group had an MUL >17 mm compared to 35% (20/57 sagittal, 20/58 coronal) of controls. The odds ratio for requiring surgery for PPI was 13.4 for sagittal MUL <9 mm and 3.2 if the MUL <12 mm.

Conclusions: Patients who had surgery for PPI had a significantly shorter MUL and sphincter volume than continent controls. Men with an MUL >17 mm are unlikely to require surgery for PPI whereas an MUL <12 mm significantly increases the risk of requiring surgery for PPI. MUL should be considered when discussing treatment options for prostate cancer.