Continence-preserving procedures for benign and malignant disease.

The musculature of the anal sphincter is not involved in ulcerative colitis and is seldom invaded directly by rectal carcinoma. Because the sphincter is capable of preserving a good degree of continence, even after removal of the entire rectum for rectal carcinoma, or even of the entire rectum and colon in ulcerative colitis, it should be preserved in most patients who require surgical treatment for these conditions. This review is primarily concerned with what type of enteric substitute should be used for the excised rectum. It addresses the issues of whether retention of a few centimeters of distal rectum above the anal high pressure zone (when permissible) is of value in patients with rectal carcinoma; whether the entire anal sphincter complex, including the so-called "sampling zone" of anal mucosa, should be preserved in the course of rectal excision for ulcerative colitis; or whether, alternatively, all mucosa above the dentate line should be removed and continuity restored by means of an endoanal, pouch-anal anastomosis. For the patient, the eventual clinical result depends on the quality of the anal sphincter, the physiologic characteristics of the "neorectum," the degree to which anal and rectal function are coordinated, and finally, the judgment and technical skill of the surgeon.