Morphology and dynamics of the male pelvic floor before and after retrourethral transobturator sling placement: first insight using MRI.

PURPOSE: We prospectively evaluated changes in morphology and dynamics of the male pelvic floor on magnetic resonance imaging (MRI) associated with retrourethral transobturator sling (RTS) placement. PATIENTS AND METHODS: Twenty-six men with post-prostatectomy incontinence consecutively underwent functional cine-MRI before and 12 months after RTS. The membranous urethra length (MUL) and severity of periurethral/urethral fibrosis were assessed on static MRI. A lowering of the posterior bladder wall (BPW), the bladder neck (BN), the external urinary sphincter (EUS) and symphysial rotation of these structures were analysed on dynamic MR images. The success rate was defined as cure (0-1 dry 'security' pad) or improvement (pad reduction ≥ 50 %).
RESULTS: The success rate was 77 % (20/26 patients). The mean follow-up was 20.4 months. The MUL significantly increased post-operatively (p < 0.001). There were no significant pre- and post-operative differences in severity of periurethral/urethral fibrosis. Significant elevation of the BPW (p < 0.021), BN and EUS (p < 0.002) was observed post-operatively. The RTS failure was significantly associated with the severity of periurethral fibrosis pre- (p < 0.032) and post-operatively (p < 0.003).
CONCLUSIONS: RTS placement is associated with MUL increase, elevation of the BN, BPW and EUS. De novo development of periurethral or urethral fibrosis seems not to be confirmed. The RTS failure was related to the severity of pre- and post-operative periurethral fibrosis. The impact of MRI on pre-operative diagnostics of RTS failure needs further evaluation.