The ileal pouch-anal anastomosis (IPAA), also known as an ileo-anal pouch, restorative proctocolectomy, ileal-anal pullthrough, or sometimes referred to as a j-pouch, s-pouch, w-pouch or an internal pouch, is an internal reservoir; usually situated where the rectum would normally be. It is formed by folding loops of small intestine (the ileum) back on themselves and stitching or stapling them together. The internal walls are then removed thus forming a reservoir. The reservour is then stitched or stapled into the perineum where the rectum was.
Ileo-anal pouches are constructed for people who have had their large intestine surgically removed due to disease or injury. Diseases and conditions of the large intestine which may require surgical removal include:
- Crohn's disease
- Ulcerative colitis
- Familial adenomatous polyposis
- Colon cancer
- Toxic megacolon
There is debate about whether patients suffering from Crohn's disease are suitable candidates for an ileo-anal pouch due to the risk of the disease occurring in the pouch, which could make matters even worse. An alternative to an ileo-anal pouch is an ileostomy.
In some cases where the pouch was formed as a result of colitis, inflammation can return to the pouch in a similar way to the original inflammation in the colon. This is known as pouchitis.
