Colectomy

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CHAPTER 16 Colectomy

BACKGROUND

The colon is a tubular digestive organ that is mainly responsible for water absorption and storage. It is 4 to 6 feet in length and extends from the ileocecal valve to the anus. The wall of the colon consists of five distinct layers: mucosa, submucosa, inner circular muscle, outer longitudinal muscle, and serosa. The outer longitudinal muscle forms three distinct muscular bands (teniae coli), which converge proximally at the appendix and distally at the rectum, where the outer longitudinal muscle layer is circumferential. The cecum, the first portion of the colon, connects to the terminal ileum via the ileocecal valve and is the portion of the colon with the largest diameter. It is fixed in the right lower quadrant by attachments to the lateral abdominal wall. The ascending colon, which is retroperitoneal, extends from the cecum to the hepatic flexure in the right upper quadrant. The hepatic flexure marks the transition to the transverse colon, which is a mobile, intraperitoneal structure. The colon becomes retroperitoneal again at the splenic flexure, which marks the transition to the more fixed descending colon. In the left lower quadrant, the descending colon becomes the sigmoid colon, which is the most narrow, muscular part of the large intestine and is extremely mobile. The rectum begins at the approximate level of the sacral promontory and terminates at the anus.

There are many indications for both partial and total colectomy. These include malignant, benign, ischemic, inflammatory, and infectious processes. The most common indications for colon and rectal resection are addressed individually later in the chapter. Common terms used to describe the types of colon and rectal operations are described in Table 16-1.

TABLE 16-1 Common Colon Procedures

Type of Resection Description
Segmental colectomy Removal of a portion of the colon (e.g., right, transverse, left, or sigmoid).
Total abdominal colectomy Removal of the entire abdominal colon, leaving the rectum and creation of an end ileostomy or ileorectal anastomosis.
End stoma Intestinal diversion involving division and exteriorization of the colon (colostomy) or terminal ileum (ileostomy) through the skin. The distal colon is then either brought out as a mucous fistula or left in the abdomen as a Hartmann’s pouch.
Loop stoma A loop of either colon or ileum is exteriorized and opened, but not divided.
Hartmann’s pouch An end stoma is created from proximal bowel; distal bowel is closed and remains in the pelvis.
Ileal pouch–anal anastomosis (Park’s pouch, J-pouch) After total proctocolectomy, the terminal ileum is used to create a reservoir that is connected to the anus as a “neorectum.”
Total mesorectal excision En bloc removal of the mesorectum along with the rectum for rectal cancers of the mid and distal rectum. This is carried out by dissection in the plane between the fascia propria of the rectum and the presacral fascia.
Low anterior resection Resection of the upper rectum; an anastomosis is formed between the colon and distal rectum.
Abdominoperineal resection Total mesorectal excision of the rectum, surrounding tissues, and lymph nodes via abdominal and perineal approaches; creation of an end stoma.
Total proctocolectomy Removal of the entire colon and rectum. Ileoanal pouch reconstruction or end ileostomy is required.

INDICATIONS FOR COLORECTAL RESECTION

I. Sporadic Cancer and Inherited Polyposis Syndromes

II. Inflammatory Bowel Disease

III. Benign Conditions