The length of intestine resection is determined by the extent of intestinal devascularization required for proper lymphadenectomy (Fig. 3). Obtaining a 5-cm margin of normal colon proximal and distal to the lesion is rarely an issue. In general, tumors located at the splenic flexure and left colon require resection of lymph nodes along the left branch of the middle colic, left colic, and first sigmoidal pedicles (Fig. 3A). Lesions in the sigmoid colon generally require lymphadenectomy along the inferior mesenteric artery (Fig. 3B). The pedicle is generally ligated distal to the left colic artery at the level of the superior hemorrhoidal artery. Routine high ligation of the inferior mesenteric artery at the level of the aorta does not improve survival, is associated with injury to sympathetic trunks, and should only be performed selectively. The rare lesion located at the junction of the left and sigmoid colon (Fig. 3C), which lies in the narrow area between the left colic and first sigmoidal pedicles, may benefit from ligation of the inferior mesenteric artery at its origin to include lymphadenectomy along all the left colic and superior rectal pedicles.

The operating surgeon stands on the patient’s left side, and the assistant on the right. Optimal exposure is initially obtained by retracting the small bowel cephalad and, to the right, in a moist laparotomy pad, using a self-retaining retractor such as a Bookwalter or Thompson retractor (Fig. 4). The sigmoid colon is first mobilized off the lateral sidewall and retroperitoneum: the assistant retracts the sigmoid colon medially, and the lateral attachment of the colon is meticulously dissected with cautery by the operating surgeon. This maneuver exposes the peritoneal reflection, which often extends onto the sigmoid mesentery. It is important to dissect the parietal peritoneum off the sigmoid mesentery to ensure entry into the correct avascular plane. This maintains the lateral position of the gonadal vessels and ureter. The left ureter is identified medial to the gonadal vessels in the retroperitoneum. The peritoneal reflection is then incised along the white line of Toldt, proximally to the splenic flexure, to mobilize the left colon. During this maneuver, care must be taken to continuously sweep the gonadal vessels and ureter laterally, in order to avoid lateral retroperitoneal bleeding. Bleeding from injury to the gonadal vessels is cautiously controlled with clips or cautery, with attention to the location of the ureter at all times.

After the sigmoid and distal left colon are mobilized, the self-retaining retractor is repositioned to allow visualization and mobilization of the splenic flexure. Lateral colonic dissection is continued along the white line of Toldt to the lower pole of the spleen. For splenic flexure lesions, the distal omentum is resected with the colon by dividing the gastrocolic ligament and gastroepiploic arcades with entry into the lesser sac. For descending colon or sigmoid lesions, the distal omentum does not necessarily need to be resected with the specimen, and the gastrocolic omentum is dissected off the distal transverse colon, which allows entry into the lesser sac. Next, using simultaneous gentle inferior tension on the transverse and descending colon,
the renocolic and splenocolic ligaments are divided with cautery. These maneuvers mobilize the splenic flexure off the retroperitoneum, including the tail of the pancreas. Care must be taken to avoid excessive retraction on the colon, as the splenic flexure is often closely applied to the inferior aspect of the spleen and undue tension can cause a splenic capsular tear, resulting in considerable hemorrhage. If spleno-omental adhesions are noted, they should be initially divided to prevent such a capsular tear when tension is applied to the omentum. Should hemorrhage occur from splenic capsular tears, hemostasis can usually be attained using a variety of methods, including argon beam coagulation and use of hemostatic agents.