The mechanics of urethral closure, incontinence, and midurethral sling repair Part 3 surgical applications (1990-2016).

Part 3 briefly summarizes further development in midurethral sling (MUS) instruments and technique following the 1990 prototype operations, then critically examines the whole MUS surgical methodology, 1990 to present day. The aim is to identify positive and negative aspects of these methodologies which can be usefully applied to improve current MUS surgery. ANIMAL EXPERIMENTS: 1987-1988 proved that a collagenous neoligament could be formed by implantation of a tape. There was a wide variation in tissue reaction to implanted tapes. Inflamamatory tissue reaction was very different from bacterial infection and was safe even when a sinus is formed. MUS METHODOLOGY: The key factor in avoiding major vessel and nerve injuries is to penetrate the perianal membrane with scissors, insert the applicator. Importantly, this reveals any bleeding which could otherwise accumulate in the Space of Retzius and only be controlled by digital pressure. The balance between too tight (retention) and too loose (incontinence) is analyzed in terms of the exponential relationship between urethral diameter and urine flow; why elastic tapes are more likely to cause post-operative urinary retention; how to minimize retention by tightening against an indwelling No18 Foley catheter; the importance of routinely repairing the distal closure mechanism with purse string suture to external ligaments, fascial layer of vagina; why minislings avoid most of the serious MUS complication; why a tensioned minisling allows greater precision when tightening the sling and how anchors and individually knitted tapes give hope that tape erosions may decrease.