#8-9 Implications of Pouch Physiology

Here are a series of papers written about ileal pouch anatomy and physiology, and the way that perversions of function produce pouch dysfunction. Amazingly very few caregivers understand this, and patients suffer the consequences of that lack of understanding.

Study #8

Church J. The Implications of Pouch Physiology. Dis Colon Rectum. 2019; 62: 510-512.

Introduction: 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.

Technique: 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.

Results: Constructing a pouch with no twists and with an open anus, maintaining liquid stool, and encouraging unhurried defecation can improve pouch function.

Conclusions: Understanding pouch physiology is important in optimizing pouch function and maintaining patient expectations.

Study #9

Church JM. The anatomy and physiology of the ileal pouch and its relevance to pouch dysfunction. Abdom Radiol (NY). 2023; 48: 2930-2934.

For the last 40 years, the ileal pouch-anal anastomosis has been used in patients with ulcerative colitis, familial adenomatous polyposis, and occasionally severe constipation to reconstruct the gastrointestinal tract after proctocolectomy. Although the procedure has generally been successful in helping patients avoid an ileostomy, it has come with its own set of problems. These include complications of the surgery such as fistulas and bowel obstruction, persistent inflammation of the pouch known as pouchitis, and functional problems related to the lack of expulsive peristalsis in the pouch. It is this last group of problems that is exacerbated by a poor diet, ill-advised anti-diarrheal medications, anal stenosis and pouch twists. Consequently, patients with pouch problems are frequently referred for radiologic evaluation, with pouchography, defecation studies, and small bowel imaging commonly requested. In this review, the basic anatomy and physiology of the ileal pouch are discussed to provide a logical baseline against which to measure the anatomy of pouches and its relationship to the symptoms of pouch dysfunction.