Small and Large Intestine

OMENTUM (OMENTAL MOBILIZATION, OMENTECTOMY)

INCISION

Beginning at the xiphoid process, make a full-thickness bilateral subcostal incision through all abdominal wall layers. Use the mid- or posterior axillary line to continue incising the abdominal wall down to the pelvis. Carry this incision anteriorly over the anterior iliac crest. Do not disrupt the inguinal regions. Now lift the anterior abdominal wall. Note that the falciform and round ligaments will have to be divided. The entire anterior abdominal wall can then be flipped caudally onto the thighs to reveal the abdominal contents (see Chapter 3, “Thorax” for chest wall mobilization to facilitate the abdominal sections.) (Fig. 5.1).

OPERATIVE PROCEDURE

Identify the blood supply to the left side of the omentum coming from the left gastroepiploic artery, which is a branch of the splenic artery. Lift the omentum to find the avascular plane between the transverse colon and omentum. Completely take the omentum away from the colon and note the attachments of the splenic flexure to the omentum and to the spleen. During transverse or left colectomy, splenic damage may occur due to traction on these attachments.

Figure 5.1 Pattern of incisions on the thorax and abdomen.

Identify the blood supply to the omentum on the right side. Notice that the blood supply comes from the right gastroepiploic artery (Fig. 5.2). (This critical artery will be addressed when dealing with the stomach.) Dissect the greater omentum free of the right gastroepiploic artery. Preserve the right gastroepiploic artery and mobilize the omentum toward the left side of the abdomen. The free pedicle of omentum may be used to wrap an anastomosis to prevent a leak.

CLINICAL HIGHLIGHTS

The blood supply to the omentum comes from both the right and left gastroepiploic arteries. The omentum can be mobilized from the left side of the abdomen or from the right side of the abdomen.

Figure 5.2 Blood supply to the stomach and omentum.
The anastomosis between right and left gastroepiploic arteries is attenuated, commonly absent (see Fig. 5.2). However, a rich crossover vascular network between the right and left is present in the body of the omentum.
Preserving gastroepiploic blood supply to the omentum allows it to be used as a wrap. Omental reinforcement of anastomoses has been described in many areas of the body. However, the length necessary to reach these areas is attained by understanding how to mobilize a viable omental pedicle as you have done in this dissection.
The left gastroepiploic artery arises from the splenic artery and travels in the presplenic fold making it difficult to identify (see Fig. 5.2).

APPENDIX (APPENDECTOMY)

INCISION

An often used incision for appendectomy is a transverse Rocky-Davis incision situated at the lateral border of the rectus muscle transversely between the iliac crest and the umbilicus (Fig. 5.3). The internal oblique and
transversus muscles are split in line with their fibers. The peritoneum is opened and retracted to gain access to the inflamed appendix.

Figure 5.3 Appendectomy, Rocky-Davis incision.

OPERATIVE PROCEDURE

The lateral peritoneal attachments of the cecum to the lateral abdominal wall are sharply and bluntly dissected free. In the operating room, a Babcock clamp can be used to assist delivery of the appendix into the wound. Use the ileal fat pad (Fig. 5.4) to guide you to the base of the appendix. This is a very reliable anatomic marker and is found on the antimesenteric border of the terminal ileum. Identify the mesentery of the appendix and ligate it with 2-0 or 3-0 silk (Fig. 5.5). With one click on a Kocher clamp, crush the base of the appendix. Then move the clamp distally on the appendix. At the crushed impression, tie off the base of the appendix with an 0-chromic ligature (Fig. 5.5). Divide the appendix along the Kocher clamp. Remove the appendix and clamp. Some surgeons use cautery and invert the base of the appendix.

Figure 5.4 Blood supply to the appendix and the ileal fat pad as a guide to find the appendix.

Figure 5.5 Steps to complete an appendectomy.

CLINICAL HIGHLIGHTS

The ileal fat pad is a consistent anatomic marker, which is very useful in the inflamed right lower quadrant. Use it to orient yourself and to find the appendix. It will reliably lead you down to the appendix even if other landmarks are obscured by inflammation or abscess formation.
Inversion of the base of the appendix is optional. If you do, a “Z” stitch may be easier to use than a purse string seromuscular stitch.

RIGHT COLON (RIGHT HEMICOLECTOMY)

INCISION

Refer to Omentum procedure.

OPERATIVE PROCEDURE

Mobilize the lateral border of the right colon from its peritoneal wall attachments. Take down the hepatic flexure by dividing the omental and peritoneal attachments (Fig. 5.6). Identify the blood supply to the right colon by tracing the middle colic artery and ileocolic artery branches, which supply the right colon from the superior mesenteric artery (SMA) (Fig. 5.7).

Mobilize the entire right colon medially in a Cattell maneuver taking down all peritoneal attachments (Figs. 5.6 and 5.8). While doing this, notice that the entire posterior attachment of the right colon consists of filmy areolar bands. Dissect from laterally to medially on the posterior abdominal wall staying anterior to the kidney. At the hepatic flexure of the colon, the surgeon will first encounter the ureter and then the gonadal vessels (Fig. 5.8). At the pelvic brim, the surgeon will encounter first the gonadal vessels and then the ureter. Watch for this consistent relationship in the operating room (Fig. 5.9).

Figure 5.6 Mobilization of the right colon, initial part of a Cattell maneuver.

Incise the posterior areolar attachments of the hepatic flexure. These are the renocolic and duodenocolic ligaments. The right colon is now mobilized and prepared for devascularization and resection (Fig. 5.10).

Divide the terminal ileum, the ileocolic artery, the right colic artery at the SMA, and the right branch of the middle colic artery. Note that the middle colic artery may be preserved depending on the location of the pathology in the colon. Once these vessels have been divided and the omentum cleared from the colon, the right colon and hepatic flexure can be divided from the transverse colon and removed.

Figure 5.7 Blood supply of the colon: find the ileocolic, right, and middle colic arteries supplying the right colon.

Figure 5.8 Mobilization of the hepatic flexure of the right colon.

Figure 5.9 Right ureter and gonadal vessels change relative positions as they descend down to the pelvis.

CLINICAL HIGHLIGHTS

Note the common blood supply to the terminal ileum and the cecum. To perform a right hemicolectomy, be sure to trace the colonic branches back to the main trunk of the ileocolic artery coming from the SMA. Do not ligate the SMA (see Fig. 5.10).

While mobilizing the posterior areolar attachments of the colon, note the proximity to the right kidney and duodenum. A tumor of the ascending colon may have local extension into the duodenum or right kidney. Oncologic resection will entail resection of these structures en bloc if invaded by tumor (see Fig. 5.8).