Left and Sigmoid Colectomy

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28.1 Left and Sigmoid Colectomy

Introduction

Left colectomy or hemi-colectomy is a resection of the colon within the territory supplied by the left branch of the middle colic artery and the inferior mesenteric artery within the embryologic partitioning of the hindgut. Common indications include neoplasia of the distal transverse colon descending or sigmoid colon; segmental ischemia; or occasionally diffuse diverticulitis. Sigmoid colectomy involves resection of the portion of the colon supplied by the sigmoid arterial cascade and superior rectal (i.e., superior hemorrhoidal artery) artery. This is the portion of the inferior mesenteric artery that lies distal to the takeoff of the left colic artery.

Surgical Principles

The pattern of left colonic resection is defined by the indication for surgery, the need to facilitate a tension-free colocolonic anastomosis, the disease process, and the blood supply. The most common indication for isolated left colonic resection is neoplasia. In this case, a radical lymphadenectomy guided by high vascular ligation is necessary for treatment and staging. 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 adequate lymphadenectomy.

Other indications for left-sided colonic resection include diverticular disease, ischemia, Crohn’s disease, sigmoid volvulus, rectal prolapse, and secondary involvement in non-colonic processes, such as ovarian carcinoma. None of these conditions mandate high ligation of the IMA, and it may be acceptable to ligate only the relevant arterial branches to the resected portion of the colon, as long as a tension-free anastomosis can be created and the remaining portions of bowel have excellent blood supply.

A high ligation of the IMA in conjunction with ligation of the inferior mesenteric vein at the inferior border of the pancreas, lateral to the jejunum, usually provides enough laxity of the remaining colon to allow the new colon conduit to reach into the pelvis for a tension-free anastomosis.