The inferior mesenteric vein and left colic artery are seen running lateral and parallel along the base of the descending colon mesentery. Using an atraumatic grasper, grasp and elevate the IMV, tenting the peritoneum beneath it. Make a superficial incision in the peritoneum under the IMV and insert the grasper into the peritoneal defect. Then, use the triangulation technique, working hand over hand to sweep down the retroperitoneum and develop the plane beneath the mesentery. The dissection is continued superiorly, to the level of the splenic vein and pancreas, and laterally toward the splenic flexure (Fig. 16.2).

The IMV is isolated and circumferentially dissected free of its peritoneal covering. Then, a high ligation is performed using an energy source (Fig. 16.3).

After secure ligation is completed, the left colic artery can be appreciated as a direct extension from the inferior mesenteric artery pedicle running in the peritoneum proximally toward the splenic flexure. In this configuration, we use an eagle sign to describe the anatomy. The inferior mesenteric pedicle is the body of the eagle, with the peritoneum under the left colic artery as the superior wing, and the peritoneum under the superior rectal artery as the inferior wing (Fig. 16.4). The left colic artery is lifted and any remaining retroperitoneal attachments are swept down, isolating the superior wing of the eagle.

The descending colon is grasped or bluntly manipulated with an atraumatic grasper and retracted toward the midline and inferiorly, exposing the attachments of the colon to the lateral sidewall. The white line of Toldt is incised, and the dissection continues proximally, staying close to the colon, to the splenic flexure (Fig. 16.5). The previous retroperitoneal dissection plane will be met. The colon is retracted medially and inferiorly, and the splenocolic ligament is divided, taking care not to avulse the splenic capsule. The omentum is suspended, and the gastrocolic ligament is divided close to the transverse colon, entering into the lesser sac. The omentum is detached from the transverse colon, moving medially to laterally to complete the splenic flexure takedown. During the detachment, stay close to the colon and assure the stomach is identified and away from the dissection. The transverse and descending colon should be fully mobilized. Alternatively, the lesser sac can be opened medially just inferior to the greater curvature of the stomach. Dissection can then be carried down in a medial to lateral fashion. Early in ones’ learning curve, this step can be performed first to assure minimizing the size of a midline incision if conversion was needed.

At this point, deliver the small bowel out of the pelvis and position to the right of the midline. A lap sponge can help hold the small bowel in place if needed.