The low-lying lesions of the rectum and rectosigmoid may be resected and bowel continuity established anterior to the sacrum in a variety of ways. Although the end-to-end anastomosis (Plate 80) can be used, side-to-end anastomosis is advantageous in cases with considerable discrepancy in size between the resected bowel and the rectal stump, particularly in obese patients. When the lesion is so low that abdominoperineal resection, with sacrifice of the rectum, ordinarily would be indicated, and in the presence of distant metastases, or when the patient refuses to give permission for a permanent colostomy, bowel continuity can be established by a very low side-to-end anastomosis. This approach may occasionally be needed in colostomy (Hartmann's) closure, and a similar ileorectal anastomosis can be used in closing an ileostomy (e.g., after total colectomy for pseudomembranous colitis).
The principles of cancer surgery should be observed, including en bloc excision of the lymphatic drainage area and early ligation of the inferior mesenteric vessels near the point of origin (Figures 1 and 2). The blood supply to the sigmoid will be sustained through the marginal artery of Drummond via the middle colic artery arising from the superior mesenteric artery. The malignant lesion of the rectosigmoid should be at least 8 cm above the anus unless the anterior resection is carried out for palliation alone. At least 5 cm and preferably more of the bowel should be resected below the malignant tumor to assure removal of all adjacent lymph nodes. The continuity can be reestablished after the descending colon, the splenic flexure, and the left portion of the transverse colon are mobilized (Figure 3).
The entire right colon can be freed from its lateral peritoneal attachments and rotated to its embryologic position on the left side of the abdomen, if more mobility is desired.
The advantages of the side-to-end anastomosis include assurance of a larger and more secure anastomosis than may be possible by the end-to-end method.
After the lesion has been proved to be malignant by microscopic examination, and polyps or secondary lesions ruled out by appropriate colonoscopic and barium studies of the colon, the patient is shifted to a clear liquid diet for a day or so before surgery. A preliminary computed tomography scan with IV contrast may reveal distal spread and locate the courses of the ureters. For cancers below the peritoneal reflection, an endorectal ultrasound study will ...