Segmental resection refers to removal of a short portion of the colon, such as a sigmoid resection, with continuity of the colon usually reestablished at the time of resection. When performed for carcinoma, wide margins should be obtained.
Anterior resection entails resection of the rectosigmoid and proximal rectum. Low anterior resection refers to resection of the rectosigmoid and distal rectum below the peritoneal reflection. Radiographically, an anastomosis is considered to be "low" if it is situated below the lower border of S2 on the lateral view . This level corresponds to the lower limit of the peritoneal reflection on the anterior rectal wall. Improved technology associated with automatic stapling devices now allows some low rectal tumors formerly treated by abdominoperineal (AP) resection to be treated with low anterior resection. Some surgeons will also perform a temporary colostomy at the time of low anterior resection to protect the rectal anastomosis. After anterior resection, the retrorectal (presacral) space will appear widened (Fig. 6.1).
Right hemicolectomy refers to resection of the terminal ileum, cecum, ascending colon, and a portion of proximal transverse colon (Fig. 6.2). The resection generally extends to the middle third of the transverse colon to provide wide margins for tumor resection and to obtain a well-vascularized incision line. An extended right hemicolec-tomy, which includes resection of the splenic flexure and proximal descending colon, is performed to treat tumors in the hepatic flexure and proximal transverse colon. When one is performing a contrast enema on patients who have had bowel resections including the
Figure 6.1. Anterior resection; widened retrorectal (presacral) space. Lateral postoperative view from a barium enema after an anterior resection demonstrates expected widening of the retrorectal space.
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