PHYSIOLOGY OF ILEAL POUCH-ANAL ANASTOMOSIS - CURRENT CONCEPTS

PURPOSE: Increasing experience with ileal pouch-anal anastomosis (IPAA ) associated with increasing knowledge about anorectal physiology has lead to a large number of publications. The purpose of this review is to evaluate the current understanding of fecal continence as revealed by the evolution of the ileoanal procedure. METHODS: Review of the lit erature covering the most important physiologic parameters involved in fecal continence was undertaken. RESULTS: Rectoanal inhibitory reflex is probably absent after IPAA but is preserved when distal anorectal mucosa is spared. Anal resting pressure decreases but is less affected when the internal anal sphincter is less traumatized. Squeeze pressur e is not importantly affected, and the importance of reservoir functio n as a determinant of stool frequency is emphasized. IPAA does not aff ect the coordination between pouch and anal canal motility in the majo rity of cases. Normal continence is preserved, even during the night, by preserving a gradient of pressure between the pouch and anal canal. CONCLUSIONS: Physiologic concepts are well established, but controver sies about the continence mechanism related to IPAA remain. The IPAA p rocedure has allowed discrimination of details about the function of m ultiple structures involved in fecal continence.