Right Colectomy

Published on 16/04/2015 by admin

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Right Colectomy

Sharon L. Stein

Introduction

A right colectomy is performed to treat a number of pathologies. Common indications include an unresectable polyp, colon cancer, Crohn disease of the terminal ileum, and right-sided diverticular disease. Ischemia and volvulus may also be indications. Resection of the terminal ileum and cecum is common to all these procedures. The distal extent of the right hemicolectomy will vary depending on the indication, oncologic principles, and adequacy of perfusion to the right or transverse colon.

Superficial Anatomy and Topographic Landmarks

Before making an incision, either laparoscopic or open, it is important to understand the relationship between surface anatomy and the abdominal anatomy (Fig. 21-1, A). Understanding the location of the most difficult part of the anatomy or most tethered portion of the colon will assist in appropriately placing an incision. Also, in the morbidly obese patient, surface anatomy, such as the location of the umbilicus, may be greatly altered. The umbilicus may reach down to the pubis and overlie a large pannus, which may distort normal relationships with internal anatomy.

FIGURE 21–1 Right colectomy and arteries of the colon.

Although the right colon is typically tethered by the ileocolic artery, lateral attachments, and the middle colic artery, the inferior portion of the right colon and ileum will be very mobile after the surgery is performed. Attachments to the middle colic and lesser sac are typically the most tethered portion of the operation. In addition, appropriate isolation and evaluation of adequate blood flow of the middle colic vessels is often the most difficult part of the case (Fig. 21-1, B). For this reason, laparoscopic extraction incisions are usually made over the middle colic arteries.

The middle colic arteries typically lie approximately midway between the xiphoid process and the umbilicus in a nonobese patient. The inferior extent of the procedure (inferior dissection of terminal ileum and cecum) is typically only centimeters below the umbilicus and medial to the anterior superior iliac spine. Therefore, an open right colectomy can often be performed through a relatively small periumbilical midline or right-sided transverse incision in a thin patient.

Anatomic Approach to Right Colectomy

Different surgical approaches to the right colon have been described and include medial to lateral, lateral to medial, inferior to superior, and superior to inferior. Varying the approach can allow for a safe, oncologically appropriate operation, depending on body habitus and pathology. Although anatomic relationships are constant, the surgeon’s awareness of proximity of structures must change.

Medial to Lateral

Many surgeons prefer a medial-to-lateral approach for for laparoscopic and often open right colectomy. This provides several benefits: the vessels are taken early in the operation, decreasing stretch and torque and providing ligation before manipulation of the tumor in the patient with malignancy. In addition, this approach demonstrates the location of the duodenum, a crucial step early in the surgery.

The medial-to-lateral approach is more difficult in patients with thickened Crohn’s mesentery; often the mesentery is extremely difficult to mobilize and resect and requires the use of Kelly clamps and suture ligature. In these patients the lateral dissection is performed early in the operation, and having obtained greater mobilization to the colon, ligation of the ileocolic vessels can safely be performed.

Identification of Ileocolic Vessels

To expose the ileocolic vessels, the small bowel must be swept to the left side or into the pelvis. Grasping and lifting the mesentery just proximal to the ileocolic valve tents the ileocolic artery (ICA), even in heavy patients. A single vessel is noted extending from the superior mesenteric artery (SMA) to the ileocolic junction. Scoring the peritoneum just below this fullness, usually with electrocautery or bipolar device, allows isolation of the pedicle. An avascular space exists below the vessel. In oncologic resections, this isolation should occur close to the SMA, including the lymphatic vessels. If performed too distally along the ICA, many branches to the ileum will be noted as the arcades are encountered, and dissection will be more tedious.

Once the avascular plane is identified, dissection can be carried posterior to the mesentery in a superior, medial, and lateral direction within this avascular space. Borders of the space will be the mesentery of the right colon superiorly, attachments of the colon to the liver superiorly and Toldt’s fascia laterally. The retroperitoneum will form the floor of the space (Fig. 21-2).

FIGURE 21–2 Retroperitoneal structures.

Just lateral to the origin of the ileocolic vessels, care must be taken to prevent injury to the duodenum, which lies close to the SMA-ICA junction. Just above the duodenum, a subtle change in fat identifies the head of the pancreas, which should also be preserved. In fact, the plane anterior to the head of the pancreas mobilizes the transverse colon mesentery to complete the medial dissection for a right colectomy. Reaching the liver superiorly, the pancreas medially, and Toldt’s fascia laterally facilitates later dissection (Fig. 21-2).

Transection of Ileocolic Vessels

Once the duodenum has been identified and the proximal ICA has been isolated, this can be transected just distal to the SMA. Means of transection include energy device, clips, staplers, and ties.

Variation in Arteries of Right Colon

Many textbooks demonstrate a distinct ICA and right and middle colic vessels, but arterial variation is common in this location. Often, the right colic artery (RCA) is either a branch from the ICA or not found at all. If a high ligation of the ICA is performed, the RCA may not need to be transected again. If it is a separate branch of the SMA, the RCA will also need to be transected, high if the operation is performed for oncologic reasons (Fig. 21-3).

FIGURE 21–3 Variations in vascular anatomy of right colon.

Middle Colic Vessels

Middle colic anatomy is often varied. A single vessel to more than five branches may extend from the SMA in this location. Level of transection will depend on oncologic principles (see Fig. 21-1, A). If a tumor is located at the hepatic flexure or proximal transverse colon, it may be necessary to resect all the branches with a high ligation. However, for a typical right hemicolectomy, only the right branch is resected. This provides additional lymphatic information with the specimen as well as important mobility to the transverse colon.

In addition to isolating and transecting the vessels, it is important to free the mesentery extending to the bowel wall. If surgery is performed laparoscopically, torque and tension may be applied while exteriorizing the bowel. Cleaning the mesentery to the bowel margin minimizes the risk of tension and prevents unnecessary bleeding.

Omentum and Lesser Sac

To mobilize the transverse colon for anastomosis and perform a full hemicolectomy, the lesser sac must be entered. Anatomically, the easiest place to enter the lesser sac is toward the midline, where layers of the omentum and lesser sac are fused. A subtle change in color or texture of fat differentiates extraneous epiploic and colonic adipose tissue from the omentum. Typically, an avascular plane close to the colon can be identified and entered.

Full dissection is ensured by visualization of the posterior aspect of the stomach, with gastroepiploic branches on the superior aspect of the stomach when elevated. In patients with hepatic flexure tumors, it may be necessary to transect and remove the omentum with the specimen for oncologic principles. The lesser sac should still be entered medially to the pathology, to ensure full mobilization. A branch of the venous drainage from the gastroepiploic vein to the colon mesentery is often noted toward the midline and may need to be transected to prevent injury.

After the lesser sac has been entered, if a full mobilization of the retroperitoneum has occurred, a thin purple plane will be noted as the hepatic flexure is approached. This will be the only remaining layer between the previous medial dissection and the hepatic flexure. Opening this layer will facilitate the dissection and identification of planes.

When approaching the line of Toldt from a superior approach, it is important to stay close to the colon just inside the white line, unless necessary for oncologic margins. If lateral to the line of Toldt, it is easy to migrate into the retroperitoneum and behind the kidney. Staying immediately on the colon side of the line of Toldt will help prevent entering the incorrect plane. Dissection is typically continued inferiorly to the cecum, just inside the line of Toldt, but preserving the fascia propria of the mesocolon.

Inferior Dissection

The inferior approach to the cecum, appendix, and terminal ileum creates a potential risk to the gonadal vessels and ureter. A thin, filmy plane separates the natural attachments from the retroperitoneum and must be carefully dissected. The ureter crosses the iliac vessels medial to the gonadal vessels, just inferior to the cecum or ileum. Identification of the ureter within the pelvis and following it back to the dissection plane can prevent injury. Once this plane has been entered, dissection should continue to ensure adequate mobility of the ileum for the anastomosis. If necessary, dissection of the small bowel mesentery off the retroperitoneum can continue all the way to the duodenum, without transection of any vessels.

Anastomosis

The mesentery of both the ileum and the colon should be dissected to the bowel wall at the level of transection before anastomosis. This reduces mesenteric bleeding during creation of the anastomosis, which may be stapled or hand-sewn.

Suggested Readings

Mancino, AT. Laparoscopic colectomy. In Scott-Conner CEH, ed.: The SAGES manual: fundamentals of laparoscopy, thoracoscopy and GI endoscopy, 2nd ed, New York: Springer, 2006.

Okuda, J, Tanigawa, N. Right colectomy. In: Milson JW, Bohm B, Nakajima K, eds. Laparoscopic colorectal surgery. New York: Springer, 2006.

Scott-Conner, CEH, Right colectomy for cancer. Chaissin’s operative strategy in general surgery: an expositive atlas, 3rd e. Springer: New York, 2002.

Sonoda, T. Laparoscopic medial to lateral. In: Wexner SD, Fleshman JW, eds. Colon and rectal surgery: abdominal operations. Philadelphia: Lippincott, Williams & Wilkins, 2012.

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