The Implications of Pouch Physiology.

Patients undergoing an IPAA experience a completely different physiology of defecation than when they had a rectum. The new "normal" is poorly appreciated and incompletely understood, and the lack of understanding has implications for pouch function. This technical note lays out the physiology of defecation with an ileal pouch and its implications for patients and surgeons. An intestinal pouch acts as a reservoir because the united antegrade and retrograde peristaltic loops produce no evacuatory pressure. Defecation occurs by gravity. Efficient defecation results in fewer stools, but inefficient defecation may cause stool frequency, incontinence, obstruction, constipation, and pouch inflammation. The technical aspects of pouch construction that impact emptying include a long efferent limb of an S-pouch, any degree of twist in the pouch body, afferent limb syndrome, and anal stenosis. Constructing a pouch with no twists and with an open anus, maintaining liquid stool, and encouraging unhurried defecation can improve pouch function. Understanding pouch physiology is important in optimizing pouch function and maintaining patient expectations.