A biomechanically based concept for a stronger obstetric anal sphincter repair.

Abstract

This study emanates from the ISPP OASIS and fecal incontinence study group at the 2018 annual meeting of the International Society for Pelviperineology (ISPP) in Bucharest, Romania. The aim was to analyze the biomechanical factors leading to the breakdown of anal sphincter repair and to suggest a more robust technique for external anal sphincter (EAS) repair. Our starting point was what happens to the EAS wound repair site during defecation following EAS repair, with special reference to the process of wound healing. We concluded that a graft no more than 1 × 1.5cm sutured across the EAS tear line would mechanically support the tear line, vastly reduce the internal centrifugal forces acting on it during defecation, thereby giving the wound time to heal. Three different grafts were discussed, autologous, biological, and mesh. Also analyzed were the effects on EAS muscle contractility of overly tight repair and overly loose sphincter repair, the latter occasioned by the tearing out of sutures and repair by secondary intention. We have analyzed causes of sphincter repair failure, introduced a graft method, preferably autologous, for the prevention thereof and supported ultrasound assessment, rather than the absence of fecal incontinence as the criterion for success of EAS repair. Although based on well-established biomechanical principles, our proposal at this stage remains unproven. Our hope is that these concepts will be challenged, clarified, and tested, preferably in a randomized controlled trial.