Ileoanal anastomosis is a surgical procedure in which the large intestine is bypassed and the lower portion of the small intestine is directly attached to the anal canal. It is also called an ileal pouch-anal anastomosis.
An ileoanal anastomosis is an invasive procedure performed in patients who have not responded to more conservative treatments. The small intestine is composed of three major sections: the duodenum, which is the upper portion into which the stomach empties; the jejunum, which is the middle portion; and the ileum. The ileum is the last portion of the small intestine and empties into the large intestine. The large intestine is composed of the colon, where stool is formed, and the rectum, which empties to the outside of the body through the anal canal.
Surgical removal of the bowel is usually a procedure of last resort for a patient who has not responded to less invasive medical therapies. For example, many patients with ulcerative colitis, an inflammatory condition of the colon and rectum, can be treated by medications or dietary changes that control the symptoms of the disease. For patients who fail to respond to these approaches, however, the creation of an ileoanal anastomosis removes most or all of the diseased tissue. Certain types of colon cancer and a condition called familial adenomatous polyposis, or FAP, in which the inner lining of the colon becomes covered with abnormal growths, may also be treated with ileoanal anastomosis.
Most patients—more than 85%—who undergo an ileoanal anastomosis are being treated for ulcerative colitis; familial adenomatous polyposis is the next most common condition requiring the surgery. The average age of patients at surgery is 35 years, and the majority of patients are male.
A surgical anastomosis is the connection of two cut or separate tubular structures to make a continuous channel. To perform an ileoanal anastomosis, the surgeon detaches the ileum from the colon and the anal canal from the rectum. He or she then creates a pouch-like structure from ileal tissue to act as a rectum and connects it directly to the anal canal. This procedure offers distinct advantages over a conventional ileostomy , a procedure in which the ileum is connected to the abdominal wall. A conventional ileostomy leaves the patient incontinent (i.e., unable to control the emptying of waste from the body) and unable to have normal bowel movements. Instead, the patient's waste is excreted through an opening in the abdominal wall into a bag. An ileoanal anastomosis, however, removes the diseased large intestine while allowing the patient to pass stool normally without the need of a permanent ileostomy.
An ileoanal anastomosis is usually completed in two separate surgeries. During the first operation, the surgeon makes a vertical incision through the patient's abdominal wall and removes the colon. This procedure is called a colectomy. The inner lining of the rectum is also removed in a procedure called a mucosal proctectomy. The muscles of the rectum and anus are left in place so that the patient will not be incontinent. Next, the surgeon makes a pouch by stapling sections of the small intestine together with surgical staples. The pouch may be J-, W-, or S-shaped, and acts as reservoir for waste (as the rectum does) to decrease the frequency of the patient's bowel movements. Once the pouch is constructed, it is connected to the anal canal to form the anastomosis. To allow the anastomosis time to heal before stool begins to pass through, the surgeon creates a temporary "loop" ileostomy. The surgeon then makes a small incision through the abdominal wall and brings a loop of the small intestine through the incision and sutures it to the skin. Waste then exits the body through this opening, which is called a stoma, and collects in a bag attached to the outside of the abdomen. In an emergency situation, the surgeon may perform the colectomy and ileostomy during one operation, and create the ileal pouch during another.
In the second operation, the surgeon closes the ileostomy, thus restoring the patient's ability to defecate in the normal manner. This second procedure generally takes place two to three months after the original surgery. The surgeon detaches the ileum from the stoma and attaches it to the newly created pouch. A continuous channel then
Because an ileoanal anastomosis is a procedure that is done after a patient has failed to respond to other therapies, the patient's condition has been diagnosed by the time the doctor suggests this surgery.
The patient meets with the operating physician prior to surgery to discuss the details of the surgery and receive instructions on pre- and post-operative care. Immediately before the operation, an intravenous (IV) line is placed in the patient's arm to administer fluid and medications, and the patient is given a bowel preparation to cleanse the bowel for surgery. The location of the stoma is marked on the skin so that it is placed away from bones, abdominal folds, and scars.
Following surgery, the staff will instruct the patient in the care of the stoma, placement of the ileostomy bag, and necessary changes regarding diet and lifestyle. Visits with an enterostomal therapist (ET) or a support group for individuals with ostomies may be recommended to help the patient adjust to living with a stoma. After the anastomosis has healed, which usually takes about two to three months, the ileostomy can then be closed. A dietician may suggest permanent changes in the patient's diet to minimize gas and diarrhea.
Risks associated with any surgery that involves opening the abdomen include excessive bleeding, infection, and complications due to general anesthesia. Specific complications following an ileoanal anastomosis include leakage of stool, anal stenosis (narrowing of the anus), pouchitis (inflammation of the ileal pouch), and pouch failure. Patients who have received a temporary ileostomy may experience obstruction (blockage) of the stoma, stomal prolapse (protrusion of the ileum through the stoma), or a rash or skin irritation around the stoma.
After ileoanal anastomosis, patients will usually experience between four and nine bowel movements during the day and one at night; this frequency generally decreases over time. Because of the nature of the surgery, persons with an ileoanal anastomosis retain the ability to control their bowel movements. They can refrain from defecating for extended periods of time, an advantage not afforded by a conventional ileostomy. One study found that 97% of patients were satisfied with the results of the surgery and would recommend it to others with similar disorders.
The overall rate of complications associated with ileoanal anastomosis is approximately 10%. Between 10% and 15% of patients will experience at least one episode of pouchitis, and 10–20% will develop postsurgical pelvic or wound infections. The rate of anastomosis failure requiring the creation of a permanent ileostomy is approximately 5–10%.
An ileostomy is a surgical alternative for patients who are not good candidates for an ileoanal anastomosis. If the patient wishes to retain continence, the surgeon may perform a continent ileostomy. Portions of the small intestine are used to form a pouch and valve; these are then directly attached to the abdominal wall skin to form a stoma. Waste collects inside the internal pouch and is expelled by insertion of a soft, flexible tube through the stoma several times a day.
Pemberton, John H., and Sidney F. Phillips. "Ileostomy and Its Alternatives." In Sleisenger and Fordtran's Gastrointestinal and Liver Disease , 7th ed. Philadelphia: Elsevier Science, 2002.
Becker, James M. "Surgical Therapy for Ulcerative Colitis and Crohn's Disease." Gastroenterology Clinics of North America 28 (June 1, 1999): 371-90.
Crohn's and Colitis Foundation of America. 386 Park Ave. S., 17th Floor, New York, NY 10016. (800) 932-2423. http://www.ccfa.org .
United Ostomy Association, Inc. 19772 MacArthur Blvd., Suite 200, Irvine, CA 92612-2405. (800) 826-0826. http://www.uoa.org .
Hurst, Roger D. "Surgical Treatment of Ulcerative Colitis." Crohn's and Colitis Foundation of America. [cited May 1, 2003]. http://www.ccfa.org/medcentral/library/surgery/ucsurg.htm .
Stephanie Dionne Sherk
Ileoanal anastomoses are usually performed in hospital operating rooms. They may be performed by a general surgeon, a colorectal surgeon (a medical doctor who focuses on diseases of the colon, rectum, and anus), or a gastrointestinal surgeon (a medical doctor who focuses on diseases of the gastrointestinal system).