Kahokehr AA, et al. - The length of the membranous (functional) urethra in male patients who had undergone the male trans-obturator sling (TOS) for post-radical prostatectomy urinary incontinence (PPI) was compared in order to gain clarity regarding the precise mechanism of action of TOS in treating PPI. For the improvement in SUI post TOS placement, 1 possible mechanism was the lengthening of the vesicourethral anastomosis to bulbar-urethra distance in the PPI setting. In order to assess and show these findings, this is the first such study utilizing dynamics MRI in continent post prostatecomty controls, incontinent pre-TOS, and post-TOS patients.