Carcinoma of the rectum: Choice between anterior resection and abdominal perineal resection of the rectum

Surgeons must know the length of grossly normal rectum or colon that must be removed distal to cancers in order to avoid cutting through microscopic carcinoma. Most pathologists now agree that five cm of normal rectum distal to the neoplasm is adequate in resections of rectal carcinoma. It is generally agreed that rectal carcinoma spreads primarily upward through superior hem-orrhoidal and inferior mesenteric lymphatics. Therefore, the decision to perform combined abdominoperineal excision or low anterior resection is predicated essentially upon the distance of the lower border of the cancer from the anus since the intra-abdominal and lateral pelvic portions of the two operations are the same. The surgeon may be advised to follow a “rule of thumb” which, if applied to the usual patient, will result in a good cancer operation, will not sacrifice anual function unnecessarily, and will not be associated with excessive complication rates. This “rule” may be stated as follows: If the lesion is easily palpable with the examining finger abdominoperineal resection is indicated; however, if the lesion, after mobilization of the rectum to the levator anus level can be brought to the level of the abdominal incision, an adequate anterior resection may be performed.