- Author: David E Stein, MD; Chief Editor: Vikram Kate, MBBS, PhD, MS, FRCS, FRCS(Edin), FRCS(Glasg), FACS, FACG, FIMSA, MAMS, MASCRS more...
Colon resections (colectomies) are performed to treat and prevent diseases and conditions that affect the colon, such as colon cancer (see the image below). Colectomies are usually performed by general surgeons or colorectal surgeons. (See Benign or Malignant: Can You Identify These Colonic Lesions?, a Critical Images slideshow, to help identify the features of benign lesions as well as those with malignant potential.)
For a better understanding of colon resections, it is important to have a thorough understanding of the terminology regarding these procedures.
A colectomy is a surgical procedure in which all or part of the large intestine is resected. The large intestine is the part of the alimentary tract that consists of the cecum, the ascending colon, the transverse colon, the descending colon, the sigmoid colon, and the rectum. For purposes of simplicity, the term colon is often used to refer to any of the components of the large intestine, save the rectum.
A colectomy that involves removing the entire colon is called a total colectomy. If most of the colon is removed, the procedure is called a subtotal colectomy. When a segment of the colon is removed, it may be called a segmental colectomy, and it may be labeled a hemicolectomy to differentiate the right and left halves of the large intestine. If the prefix "procto-" precedes the term colectomy (ie, proctocolectomy), the procedure involves the removal of the rectum in addition to the colon. Removal of only the rectum is referred to as a proctectomy.
Other terms used include low anterior resection, which classically refers to removal of the sigmoid colon and upper rectum and derives its name from the fact that the dissection is below the anterior reflection of the peritoneal lining. Although the rectum is anatomically distinct from the colon, many pathologic conditions and procedures related to the colon also involve the rectum. Therefore, surgical procedures involving the rectum (eg, abdominoperineal resection [APR]) have been included in this article.
Colectomies are performed to treat and prevent diseases and conditions that affect the colon.
The American Society of Colon and Rectal Surgeons has issued practice parameters that discuss the use of colectomy in colon cancer, rectal cancer, ulcerative colitis, and sigmoid diverticulitis.
Some of the most common indications for colon resection are discussed below.
Colorectal cancer has a lifetime incidence of 6% and is the second leading cause of cancer death in the United States. It affects slightly more men than women and is curable with surgery if caught early. A colectomy for colon cancer requires removal of the tumor-affected portion of the colon and/or rectum and adequate margins, as well as the blood supply to that segment. In the vast majority of cases, primary anastomosis is performed.
Cecum and ascending colon cancer
Treatment for cecum and ascending colon cancer is a right hemicolectomy, which involves removing the distal 5 cm of the terminal ileum, the cecum, the ascending colon, the hepatic flexure, the first third of the transverse colon, and associated fat and lymph nodes. By convention, the dissection includes the right branch of the middle colic artery.
Transverse colon cancer
The treatment of transverse colon cancer is controversial and depends on the location of the cancer. For proximal transverse tumors and midtransverse tumors, the authors perform a right hemicolectomy. Similarly, for distal transverse tumors, even at the splenic flexure, the authors often perform an extended right colectomy. Because the cancer cells drain proximally, it is important to remove the lymph node basin proximal to the tumor. The distal margin of resection in an extended right hemicolectomy is the proximal descending colon.
Takedown and resection of the splenic flexure is followed by an anastomosis between the ileum and the upper descending colon, with the distal limb of the anastomosis dependent on blood supply from the left colic artery. The key point is takedown and resection of the splenic flexure. It is not advisable to make an anastomosis in the region of the splenic flexure, because this region is a watershed zone. Once the middle colic artery is divided, the splenic flexure becomes entirely reliant on blood supply from the inferior mesenteric artery (IMA).
One type of operation described is a limited transverse colectomy. In this procedure, only the part of the transverse colon containing the lesion is resected, followed by anastomosis of the remaining ends. This operation would be feasible for midtransverse cancers that are strictly limited to the transverse colon (ie, the cancer does not involve either flexure). However, if too much of the transverse colon is resected, tension may prevent a safe anastomosis, necessitating mobilization of both the hepatic and the splenic flexure. In such cases, it is better to perform an extended right colectomy.
Descending colon cancer
The treatment required for descending colon cancer is a left hemicolectomy, with takedown of the splenic flexure, followed by anastomosis of the transverse colon to the upper sigmoid. Depending on the extent of the cancer, the sigmoid colon may also be resected, in which case the transverse colon would be anastomosed to the rectum.
Sigmoid colon cancer
Treatment for sigmoid colon cancer is resection of the sigmoid colon, with the descending colon anastomosed to the upper rectum.
The type of resection for rectal cancer depends on the exact location of the cancer. The two common surgical options for treating rectal cancer are low anterior resection and APR.
If the cancer is located in the upper rectum, the cancer-affected portion of the rectum is removed, along with surrounding lymph nodes, as long as a 5-cm distal mucosal margin can be obtained. The colon is then joined to the rectal stump. A circumferential dissection that includes the fascial envelope around the rectum, termed a total mesorectal excision (TME), is imperative. If the cancer is in the middle to lower rectum and complete TME is performed, only a 2-cm distal margin is needed. These margins are important: If the tumor is too low and a margin cannot be obtained, the sphincter complex must be removed, which requires a permanent colostomy (termed an APR).
Other terminology used includes coloanal anastomosis, intersphincteric dissection, and colonic pouches. When the entire rectum must be removed for cancer clearance, the descending colon can be sewn to the anal sphincter complex at the dentate or pectinate line; this is termed a coloanal anastomosis. If the cancer is very low, the authors often remove the internal sphincter with the specimen to obtain a better margin; this is known as an intersphincteric dissection.
The rectum acts as a reservoir for feces. When a portion of the rectum is removed, a rectal stump shorter than 6 cm may lead to problems with both continence and evacuation. Rectal stumps that are longer than 12 cm do not significantly alter function.
In cases of a low anterior resection in which less than 6 cm of rectal stump remains, the surgeon may create a colonic pouch, often called a J pouch or coloplasty, so that the patient may achieve better continence postoperatively. A pouch is an extra reservoir to help store stool. This reservoir is created by stapling or sewing loops of colon together to make a pouch and then attaching the pouch to the anus. Studies have shown that colonic pouches are superior to coloanal anastomosis in that a J pouch results in a decreased anastomotic leak rate, a better continence rate, better control of urgency, better control of flatus, and fewer stools per day.
Colonic diverticular disease
Not all cases of diverticulosis necessitate colon resection. In fact, diverticulosis is usually asymptomatic and is often an incidental finding on screening colonoscopies or diagnostic laparoscopies. However, when diverticulosis is complicated by diverticulitis or if it presents with massive bleeding, a colon resection may be required.
Mucosal and submucosal outpouchings in the colon are called diverticula. They are false diverticula and are a phenomenon of a diet low in complex carbohydrates and dietary fiber. By age 70 years, more than 50% of people in the United States have colonic diverticulosis.
In general, the only operative indication for surgery in diverticulosis is for hemorrhage. Diverticulosis may cause a massive lower gastrointestinal (GI) bleed, and if this cannot be controlled with endoscopy or interventional radiology, surgery may be required. If the area of the bleed is localized with angiography, a segmental resection corresponding to the bleeding may be performed. In an unstable patient or one who has been transfused with more than 10 units of blood upon hospital admission or more than 6 units of blood in 24 hours or is hemodynamically unstable, an emergency subtotal colectomy may be required.
Diverticulitis is a perforation of a diverticulum. Diverticulosis does not always result in diverticulitis. Furthermore, not all cases of diverticulitis warrant colon resection. Acute uncomplicated diverticulitis can often be treated successfully with bowel rest and antibiotics alone. The decision to undergo surgical intervention is made on a case-by-case basis.
The indication for colon resection is recurrent attacks or complicated diverticulitis, which is characterized by perforation, obstruction, abscess, or fistula. In general, the authors try to convert an emergency procedure into an elective one. In a case of a free perforation with feculent peritonitis, a Hartmann procedure is often performed, which involves resection of the inflamed segment of large bowel followed by an end colostomy and a stapled rectal stump. The colostomy can then be reversed 3-6 months postoperatively.
Bowel perforation is a medical emergency that necessitates immediate surgical intervention. In addition to occurring as a consequence of penetrating injuries such as stabbing or gunshot wounds, bowel perforation can occur as a complication of colonoscopy or other procedures. Bowel perforation can even result from blunt trauma.
Bowel perforation does not always call for a colectomy. If the lesion is small enough, a primary repair can be performed. Factors that may preclude primary repair include severely inflamed tissues, feculent peritonitis, distal obstruction, presence of a foreign body or tumor, and an impaired blood supply.
Inflammatory bowel disease
Total proctocolectomy is the only curative treatment for ulcerative colitis. It is indicated when medical management fails or is intolerable owing to the side effects of the medication. In addition, surgical treatment is indicated in patients who develop dysplasia or colon cancer. Surgery alleviates symptoms and eliminates the risk of colonic adenocarcinoma. As in low anterior resections, a J pouch is made (in this case with small intestine) to improve the patients' quality of life postoperatively by restoring intestinal continuity.
There is no cure for Crohn disease. Although colectomy does not cure Crohn disease, it is indicated for refractory Crohn colitis, colonic strictures, or fistulas that affect the overall well-being of the patient. It is imperative that as much of the small intestine is preserved as possible. Patients with Crohn disease are often young and will likely require additional surgeries at later stages of life.
The colon is supplied by the superior mesenteric artery (SMA) and the IMA. A compromise of blood supply to the colon results in ischemic colitis that can progress to bowel infarction if left untreated. Infarction can result from an occlusive embolus in one of the arteries that supplies the colon or from the vasoconstrictive effects of strong vasopressors. An infarcted bowel can rapidly develop into a perforated bowel. Therefore, bowel infarction or colon ischemia is a surgical emergency.
Colonic inertia, a very specific form of slow-transit constipation, may be treated with subtotal colectomy. Surgery is advised when diagnostic tests such as a sitz marker study reveal profound dysmotility of the colon. Medical measures (eg, fiber supplementation, stool softeners, laxatives, enemas, rectal suppositories, and biofeedback) should be tried first. In addition, the surgeon should also evaluate the patient for obstructive defecation and pelvic floor dysfunction as part of the preoperative workup.
Obstructive defecation, whether due to muscle dysfunction or a rectocele, may coexist with a transit abnormality. If the patient has both, the obstructive defecation should ideally be resolved before surgery, but if it cannot be resolved, the surgeon may still proceed with colectomy. If a colon resection is to be performed, a subtotal colectomy with an ileorectal anastomosis is the procedure of choice.
There is some controversy in this area. Many surgeons believe that leaving some of the distal sigmoid colon may help prevent debilitating diarrhea. Partial colon resection has met with very limited success in the past and has been abandoned by the overwhelming majority of surgeons. Preoperatively, the surgeon should obtain objective documentation of slow colonic transit by ordering a colon transit study. Tests such as anorectal manometry, electromyography, and defecography are useful in assessing for obstructive causes.
The surgeon should also be wary of patients who have adult-onset constipation. Both iatrogenic (eg, narcotic use, medicinal side effects) and psychological causes of constipation (eg, voluntarily withholding stools out of fear of pain or fear of public restrooms) should be ruled out. Colectomies should be performed only in psychologically stable patients with an identifiable physiologic abnormality.
Familial adenomatous polyposis
Patients with familial adenomatous polyposis (FAP) develop hundreds to thousands of noncancerous polyps in the colon as early as their teenage years. These polyps are premalignant and will develop into cancer. The average age at which an individual with FAP develops colon cancer is 39 years. Thus, these patients may choose to undergo prophylactic colectomy.
Hereditary nonpolyposis colorectal cancer
Like FAP, hereditary nonpolyposis colorectal cancer (HNPCC) is an inherited colorectal cancer syndrome. Although patients with HNPCC do not develop as large a number of polyps as those with FAP do, they have an 80% lifetime incidence of colorectal cancer. Surgical resection of the entire colon is the only definitive way of preventing colon cancer. Thus, patients with HNPCC may choose to undergo prophylactic total colectomy or proctocolectomy.
Colectomy has no absolute contraindications, though the overall medical status of the patient and the indication for surgery should be evaluated on a case-by-case basis. A patient with severe cardiac disease who has a large polyp in the cecum that is not amenable to colonoscopic removal is a classically difficult case. The physician has to weigh the risks and benefits of the surgical procedure against the projected outcomes of inaction. A patient with severe cardiac disease or one who cannot tolerate anesthesia may not be a candidate for surgery. It should be routine practice to discuss the potential outcomes with the patient and his or her family.
In terms of approach, laparoscopic colectomy has some relative contraindications. Intra-abdominal adhesions or scar tissue from previous abdominal surgical procedures may preclude a laparoscopic approach. In addition, a phlegmon due to perforated diverticulitis would make laparoscopic colectomy difficult to perform.
As for all laparoscopic abdominal operations, the inability of the patient to tolerate insufflation is a contraindication for laparoscopic colon resection. Therefore, preoperative pulmonary function studies are prudent in patients suspected of having breathing difficulties.
The surgeon should also note whether the patient has a bleeding disorder or liver disease. Portal hypertension, though not an absolute contraindication, can result in massive hemorrhage intraoperatively, a dangerous and challenging situation to control even in the best of circumstances.
Finally, if a 15-cm tumor must be extracted or if a tumor is invading abdominal wall muscle of pelvic attachments, the decision whether to perform laparoscopy may depend on the individual surgeon’s skillset.
Perioperative complications due to colon resections may include wound infection, pelvic abscess formation, anastomotic leakage, bleeding, or injury to other organs/structures. The surgical site infection (SSI) rate at the authors’ institution as per the National Surgical Quality Improvement Program for colon resections is 6%, and the anastomotic leak rate is 2%. The incidence in the literature ranges from 4% to 38%. The rate of the other complications is less than 2%.
To prevent complications, prophylactic antibiotics should be administered within 30 minutes of incision. Suggested antibiotic regimens for colectomy include the following:
Cefazolin 1 or 2 g plus metronidazole 500 mg
Ertapenem injection 1 g
Levofloxacin 500 mg plus metronidazole 500 mg (if the patient is allergic to penicillin)
In addition, the authors prescribe a Nichol preparation the night before surgery, which consists of an erythromycin base and neomycin (1 g each at 5 pm, 6 pm, and 9 pm). Mechanical bowel preparation is used for left, sigmoid, and rectal resections.
To reduce the risk of infection after surgery, the authors irrigate the rectum with dilute povidone-iodine before performing left and sigmoid colectomies, as well as proctectomies.
To prevent deep venous thrombosis (DVT), all patients should have sequential compression devices and receive heparin or low-molecular-weight heparin subcutaneously within 2 hours of surgery.
Outcomes after colon resection are excellent. The average length of stay at the authors’ institution is in the range of 4-5 days. As mentioned above, it is imperative to try to maintain low SSI rates by using appropriate technique and maintaining an attention to detail. Specific outcomes are based on the indication for surgery. For example, the recurrence rate after an attack of diverticulitis is less than 5%. The cancer recurrence rate is based on the final pathologic stage of the cancer.
The Clinical Outcomes of Surgical Therapy (COST) and Colon Cancer Laparoscopic or Open Resection (COLOR) trials found laparoscopic surgery for colon cancer to be as effective as open colectomy in preventing recurrence and death from cancer. Clinical trials also found there to be no significant increased risk of seeding tumor at port sites or spreading tumor by laparoscopic colectomy.
With respect to transverse colon cancer, which was excluded from the COST study, Agarwal et al compared laparoscopic colectomy with open colectomy for stage I-III adenocarcinoma. They found complication rate and severity, 5-year survival, and disease-free survival to be similar in the two groups, and they found the laparoscopic approach to be superior in terms of short-term recovery and lymph node harvesting.
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