A permanent ileostomy following removal of the colon can be avoided in selected patients by removing all diseased colon down to the top of the columns of Morgagni or the pectinate line, followed by construction of an ileal reservoir, with anastomosis of the anal canal (Figure 1). Patients with ulcerative colitis and polyposis are candidates for this procedure, but those with Crohn's disease are not, because of the potential for involvement of the small intestine. The patient must have an adequate anal sphincter by digital examination or, better yet, by manometry. The rectum should be free of ulcerations, abscesses, stricture, fissures, or fistulae. This is especially important in patients with ulcerative colitis (UC). This procedure can be considered in patients who are strongly opposed to an ileostomy and who are available for prolonged close follow-up. The patient should thoroughly understand the uncertainties of postoperative anal control and the need to have patience during the early months after the operation. The procedure is not recommended for patients older than 65 years and those who have fecal incontinence. Obesity may make it impossible to perform the anal pouch anastomosis. In patients with Familial Adenomatous Polyposis (FAP) desmoids tumors involving the small bowel mesentery can make it difficult to obtain adequate length to reach the anus with the pouch. All patients should realize that a permanent ileostomy can sometimes be required due to factors not known until the procedure is underway.
Various surgical procedures have been used in an effort to improve long-term anal continence. It is questionable whether any procedure currently used is always completely successful, and the patient should be informed of this uncertainty. Increasing experience suggests the use of some type of anal pull-through procedure has a reasonable chance of providing more comfort than the terminal ileostomy or the ileal abdominal pouch.
A prolonged period of preoperative hyperalimentation or nonalimentation with catabolism may be avoided by a staged procedure, especially in the presence of toxic megacolon, poor general condition, or rectal disease. A permanent ileostomy is performed with subtotal colectomy, leaving the rectum in place, and the superior hemorrhoidal vessels undivided. This also offers the chance to review the pathology of the colon to further exclude Crohn's disease. After several months, an ileoanal anastomosis is considered and a diverting ileostomy is created at the time of the pouch. After a suitable recovery the temporary ileostomy is closed making this a three-stage procedure. Various pouches have been advocated. They include the J pouch (Figure 2, A), the three loop S pouch (Figure 2, B), the lateral isoperistaltic ileal reservoir (Figure 2, C), and the four-loop W reservoir (Figure 2, D).
Documentation of the pathologic process involved is done with biopsies taken from the anal canal as well as the rectum or colon. The stomach and duodenum are inspected by gastroduodenoscopy. Patients with polyposis and UC patients with high-grade dysplasia should be informed of the potential for malignancy. It is important to have medical and surgical agreement that surgical removal of the entire colon is in the best long-term interest of the patient. Time is usually required for the patient to accept the recommendation and the patient can benefit from talking with another patient who has undergone this procedure. The patient's medications, including steroid therapy for ulcerative colitis, must be considered, and steroid therapy continued. Intravenous antibiotics are given before operation, and any major blood volume deficit is corrected. Patients receive a clear liquid diet for a day or two and an oral bowel preparation the day before.
In severe cases, some prefer a 6-week period of intense medication to keep the colon at rest permitting the inflammatory reaction to subside. Such patients may be placed on total parenteral alimentation, systemic steroids and steroid enemas, and systemic antibiotics when ulcerative colitis is present. The rectal mucosa is evaluated by sigmoidoscopic examination immediately prior to the operation. A large rectal tube is placed for irrigation with saline and povidone-iodine antiseptic solution.
General endotracheal anesthesia is preferred.
The patient is placed in the modified lithotomy position using Allen stirrups. This allows the abdominal as well as perineal dissections to be performed without repositioning of the patient.
The rectum is given a very limited low-pressure irrigation, and the perianal skin and buttocks are given the routine skin preparation. Constant bladder drainage is instituted and a nasogastric tube is inserted. The pubis and abdominal skin are also prepared in the routine fashion, and sterile drapes are applied.
A lower midline incision that extends to the left of the umbilicus is made, and the abdomen is explored. Particular attention is given to the entire small intestine to make certain there is no evidence of Crohn's disease, which would contraindicate the operation. The involvement of the colon with inflammation or polyposis is evaluated. In the presence of polyposis, the possibility of encountering an unsuspected site of malignancy or metastases to the liver is ever present. If there is any question of Crohn's colitis, the colon is resected and sent to the pathologist for gross and microscopic verification.
The colon may be constricted, friable, and quite vascular, with firm attachments to the omentum. Gentle traction is applied to avoid tearing the friable bowel with resulting gross contamination. The mesentery of the colon can be divided and blood vessels ligated relatively near the bowel wall, except in diffuse polyposis, where there is always a possibility of metastases to regional lymph nodes. It is judicious to have the pathologist evaluate the entire specimen as soon as possible.
Before proceeding with the removal of the mucosa from the lower segment and before constructing the ileal reservoir, it is essential that sufficient ileum has been mobilized to construct the pouch. Approximately 50 cm of terminal ileum is required for the construction of the ileal reservoir. Such mobilization is accomplished by dividing the ileocolic vessels and the mesentery down to near the arcade of vessels at the very end of the ileum, but none of the latter is ligated (Figure 3). It may be necessary to evaluate the mobility of the small bowel all the way up to the ligament of Treitz with division of any bands that tend to limit the mobility of the small intestine (Figure 4). Incisions within the posterior peritoneum may be worthwhile to provide added mobility. Some divide the last ileal arcade (Figure 4). The adequacy of the blood supply involved should be evaluated frequently to be certain a vigorous blood supply is sustained to the end of the mobilized ileal terminal. The end of the proposed pouch should reach at least to the pubis, and preferably to the edge of the Bookwalter ring being used for retraction.
The dissection below the rectosigmoid junction is carried out close to the bowel wall to avoid damage to the presacral and parasympathetic nerves. The rectal stump is washed out with povidone-iodine, and the bowel divided at the anorectal junction. This leaves a stump about 3 to 4 cm in length (Figure 5). Some prefer to have a longer rectal anal stump, which requires resection of the rectal mucosa from above rather than entirely through the anus. Others use a stapling instrument for closure of the rectal stump.