Colon and Appendix

Abstract

Almost 150,000 new cases of colorectal cancer are diagnosed each year in the United States, making them the fourth largest group of new cancer patients. Consequently, colorectal cancer claims 50,000 lives annually. Ninety to ninety-five percent of colon tumors are adenocarcinomas; less frequent types include carcinoids, stromal tumors (formerly leiomyosarcomas), lymphomas, and undetermined lesions. Surgery remains the cornerstone of curative therapy, with the greatest technical advances made in recent years using minimally invasive methods, including laparoscopy and robotics. Indeed, multiple randomized trials have demonstrated equal outcomes for the traditional open approach and the laparoscopic approach to colon cancer surgery.

Regardless of the type of surgical approach to colon cancer, location continues to be the major determinant of the type and extent of colon resection; the degree of resection is based on the arterial, venous, and lymphatic drainage of the affected colon segment. Furthermore, medical societies and healthcare payers are increasingly relying on the adequacy of lymph-node resection, and therefore the number of nodes examined histologically, as a benchmark of satisfactory oncologic therapy.

Appendices

Appendix Surgical Anatomy

Topography

The appendix extends from the base of the cecum as a long tube with varying length, but averages about 9–10 cm. While the base of the appendix emerges at the convergence of the teniae coli, the tip of the appendix can be found in various positions. The retrocecal location is the most commonly encountered position of the appendix. The appendix is typically located inferior and posterior to the fold of Treves, a triangularly shaped antimesenteric epiploic appendage that marks the junction of the ileum and the cecum. The fold of Treves is useful in identifying the appendix when using small-incisions, and can frequently be used to locate the appendix on computer tomography.

Blood Supply

The appendiceal artery is a branch of the ileocolic artery that runs through the mesoappendix.

Figure 8.22

Nerve Supply

The appendix is innervated by both the parasympathetic and sympathetic divisions of the autonomic nervous system, duplicating the innervation of the cecum.

Lymphatic Drainage

Lymphatic drainage from the appendix is encompassed in the right colon distribution.

Surgical Applications

Malignant tumors arising from the appendix are rare. Carcinoids are the most common appendiceal neoplasm, and are often found incidentally during appendectomy for acute appendicitis. When carcinoids exceed 2 cm in size, malignancy risk increases and a formal right hemicolectomy is indicated. In carcinoid tumors smaller than 2 cm and localized, only a simple appendectomy is needed.

Adenocarcinomas are more inclined to produce symptoms than carcinoids are. The common histologic variants of adenocarcinoma are well-differentiated or mucin-producing tumors (malignant mucocele) or poorly differentiated adenocarcinomas. Both of these lesions can metastasize to regional nodes and distant sites. Adequate treatment requires a mesenteric resection encompassing the primary nodal drainage system. If the diagnosis of an adenocarcinoma is made incidentally, as in an appendectomy specimen, subsequent right hemicolectomy offers the greatest curative potential.

In summary, right hemicolectomy is indicated if the appendiceal tumor is an adenocarcinoma, mucin-producing tumors, has lymphatic invasion or direct invasion of the serosa or mesoappendix.

Incision for Appendectomy

The terms Rockey-Davis and McBurney's incisions are probably of historical interest, with most surgeons describing their technique as some variation of a right lower quadrant incision (e.g., curvilinear, transverse, oblique). Classically, a transverse incision of approximately 6 cm is made at one-third the distance from the anterior superior iliac spine to the umbilicus. Obviously, in very obese patients, this landmark is not feasible and for such patients, a laparoscopic appendectomy may be desirable. The dissection is carried down through the subcutaneous fat until the external oblique aponeurosis is identified and an incision is made along the grain of its fibers. The underlying muscle layers are split (without cutting) using two Kelly clamps alternatingly opened in perpendicular directions until the peritoneum is visible. The peritoneum is incised with Metzenbaum scissors to enter the abdominal cavity.

In cases where malignancy or perforation is suspected, a wound protector may be advantageous to reduce surgical site infections, and the theoretical possibility of tumor implants within the incision.

After the peritoneum is opened, the appendix is identified by following the cecal taenia distally, and the cecum and appendix are delivered into the wound by gentle traction. Occasionally the lateral peritoneal reflection of the cecum is divided to improve exposure. These maneuvers should bring the cecum and appendix to the anterior abdominal wall, facilitating removal without vigorous retraction. Freed from any attachments, the mesoappendix can be identified, divided between clamps, and ligated to control the appendicular artery.

In perforated appendicitis, when the wound is contaminated, it is still best to leave a portion of the skin wound open for secondary closure. Most appendectomies do not require postsurgical drainage.

Appendectomy

Once the appendix is delivered out of the abdominal cavity, the base of the mesoap-pendix can be ligated using a clamp and dividing between 2–0 or 3–0 silk or absorb-able ties. It is also possible to ligate the mesoappendix using bipolar energy sources such as the LigaSure device (Covidien, Boulder, CO). Once the appendiceal mesentery and artery are ligated, the appendix can be divided.

Figure 8.23

Figure 8.24

To divide the appendix, a straight hemostat can be applied to its base 5–10 mm from the cecum. The appendix can be transected with a blade above the hemostat, and 2–0 silk or absorbable ties applied below the hemostat. We prefer a double tie in case one tie slips. Some surgeons advocate applying cautery to the appendiceal stump mucosa to mitigate risks of mucocele formation.

If the surgeon wishes to invert the appendiceal stump, a Z-stitch is then placed as a Lembert suture in the cecum, around the base of the appendix. Prior to tying the suture, the appendix is inverted into the cecum with a clamp or forcep, and the suture is tied down, leaving the stump inverted. An alternative to the Z-stitch is to perform a purse-string suturing around the base of the stump.

There is no proven advantage or disadvantage to stump inversion or cauterizing the mucosa, and the divided appendix can simply be left alone. Pitfalls and dangers to appendectomy are the finding of inflamed cecum, possibility of cecal Crohn's disease, and poor vascular control in edematous mesoappendix. In cases where the bleeding vessel is not visible, it is advisable to perform suture ligature.

Laparoscopic Appendectomy

Laparoscopic appendectomy can be performed by multiple trocars or through a single incision in the umbilicus. The patient is positioned supine, with the operating table oriented partially in Trendelenberg and right-side up. At least one trocar should be a 10-mm trocar. The base of the appendix is identified and a window is made at the base of the mesoappendix adjacent to the appendix using dissecting forceps. The window should be large enough to accommodate a blue endoscopic cutting stapler to divide the appendix at its base. The mesoappendix can be divided with a vascular-load endoscopic cutting stapler, the Ligasure bipolar cautery, or a preformed tie. The specimen can be retrieved lengthwise out of the 10-mm trocar or with a specimen retrieval bag.

Figure 8.25

A pitfall of laparoscopic appendectomy, especially when a retrocecal appendix is encountered, is leaving a residual appendical stump that is too long, or encountering inflammation close to the base of the appendix. With the use of endoscopic cutting staplers, it is appropriate in the latter circumstance to divide a cuffof healthy cecum along with the appendix specimen.

Anatomic Basis of Complications

• Right colectomy

  • Injury or inadvertent ligature of superior mesenteric vessels.

  • Injury to the retroperitoneal duodenum, for both laparoscopic and open approaches.

  • Injury to the right ureter if dissection of the mesentery is deeper than the avascular plain.

  • Avulsion of venous branch between inferior pancreaticoduodenal and middle colic veins, particulary in aggressive medial retraction during open colectomy.

  • Lateral colon mobilization enters retroperitoneal fat and the kidney.

• Left colecotmy

  • Excessive traction on the descending colon before dividing the lineocolic ligaments can cause splenic capsule laceration.

  • Inadequate mobilization of colon length creates tension at an anastomosis and increases the risk of leakage.

  • Injury to the left ureter if dissection is carried deeper than the avascular plain.

  • Laparoscopic dissection deep into lumbar vessels.

• Rectosigmoid colectomy

  • Presacral hemorrhage

  • Injury to ureters as they cross over the ileac vessels.

  • Anastomotic tension from failure to mobilize splenic flexure.

Key References

Milsom JW, Böhm B, Nakajima K, Tonohira Y (editors). Laparoscopic colorectal surgery. New York: Springer; 2006

This reference provides practical anatomic and technical pointers to minimally invasive colorectal surgery with updated diagrams from its previous editions.

WolffBG, Fleshman JW, Beck DE, Pemberton JH, Wexner SD (editors). The ASCRS textbook on colon and rectal surgery. New York: Springer; 2006

This is now a standard text from expert members of the ASCRS in private and academic practice. The chapters on laparoscopic approaches are by recognized experts.

Gordon PH, Nivatvongs S (editors). Principles and practice of surgery for the colon, rectum, and anus. 2nd ed. St Louis: Quality Medical Publishing; 1999

A text written by a few surgeons with wide ranging experience offering practical approaches to colon cancer surgery.

Delaney CP, Neary P, Heriot AG, Senagore AJ (editors). Operative techniques in laparoscopic colorectal surgery. New York: Springer; 2006

Offers stepwise discussions and illustrations on laparoscopic colorectal surgery, particularly with anatomic pointers through the view of the laparoscope.

Scott-Conner CEH, Henselmann C. Chassin's operative strategy in colon and rectal surgery. New York: Springer; 2006

Known for clarity in writing for rapid review. The diagrams and illustrations are among the most descriptive of any text.

Kaisser AM, Nunoo-Mensah JW, Beart RW. Tumors of the colon. In: Zinner MJ, Ashley SW, editors. Main-got's abdominal operations. 11th ed. New York: McGraw-Hill; 2007. p. 625–59

This chapter highlights the principles of oncologic colon surgery as well as rationale.

Pappas TN, Pryor AD, Harnisch MC (editors). Atlas of laparoscopic surgery. 3rd ed. New York: Springer; 2008

Beneficial as a photographic atlas with some discussions on instruments used in laparoscopic colon surgery.