Bradley J. Champagne and Thomas J. Edwards

Introduction

Left colectomy is a resection of the colon within the territory supplied by the inferior mesenteric artery. The arterial supply of the colon is divided by the embryologic partitioning between midgut and hindgut, so a left colectomy is a resection of the hindgut, excluding the rectum. Terms such as left hemicolectomy, sigmoid colectomy, and sigmoid wedge resection also apply to left-sided colonic resection. Common indications include neoplasia, ischemia, and diverticulitis.

Surgical Principles

The pattern of left colonic resection is defined by the indication for surgery, the need to facilitate a tension-free colo-colonic anastomosis, and the blood supply. The most common indication for isolated left colonic resection is neoplasia. In this case, a radical lymphadenectomy is necessary for staging and prognosis, and lymphatic drainage must be considered. Because the pattern of lymphatic drainage for the colon follows that of the arterial supply, the inclusion of the mesocolic envelope containing the inferior mesenteric artery (IMA) and its branches, with ligation of the IMA close to its origin, ensures that this is achieved. This is referred to as a high ligation of the IMA. This approach may devascularize the entire left colon, requiring its resection and the mobilization of the distal right colon for anastomosis to the upper rectum.

Other indications for left colonic resection include diverticular disease, ischemia, Crohn disease, sigmoid volvulus, rectal prolapse, and secondary involvement in noncolonic processes, such as ovarian carcinoma. None of these conditions requires high ligation of the IMA, and in these cases it may be acceptable to ligate only the relevant branches of the IMA, perform a less extensive mobilization of the left colon, and create a tension-free anastomosis.

Anatomy for Preoperative Imaging

For colonic carcinoma, computed tomography (CT) of the chest, abdomen, and pelvis provides preoperative staging of the disease. CT includes identification of distant metastases, gross local lymph node involvement, and local invasion of the primary tumor (Fig. 22-1, A). Full colonoscopic evaluation determines the presence of synchronous lesions. For benign disease, CT and colonoscopy may help to identify pathologic features, such as the extent of Crohn disease or ischemia, that may affect approach and extent of dissection.

Surface Anatomy, Incision, and Port Placement

Left colectomy may be performed as either an open or a laparoscopic procedure. For either approach, the patient should be in the Lloyd-Davis position, supine, with the patient’s buttocks at the foot of the table and legs slightly flexed in the horizontal position and held in leg supports. For a laparoscopic approach, the patient is secured with gel pad or bean bag in anticipation of an extreme head-down and right lateral tilt position.

A number of different port configurations have been described; the authors’ preferred approach is shown in Figure 22-1, B. Open left hemicolectomy may be performed through either a midline or a left transverse incision.

Vascular Anatomy

The anatomy of the vascular supply to the colon is demonstrated in Figure 22-2. Knowledge of these vessels, the autonomic nerves, and the lymphatic drainage, as well as its relationship to the spleen, pancreas, kidney, and ureter, is required for successful completion of the left hemicolectomy (Figs 22-3 and 22-4, A).