Volvulus arises from a twist of the colon on its mesentery sufficient to produce intestinal obstruction. An unusually long, mobile mesentery in the affected segment or a lack of fixation is needed for Ihe twist to occur. Unless the obstruction is relieved, il progresses proximally and distally because of gas formation within the occluded segment. As a result, the mesenteric vasculature supplying the involved segment is also occluded, and gangrene and perforation can follow.
Common in the elderly, volvulus is mosl prevalent in inaclive women who have restricted mental capabilities and live in nursing homes. The combination of an unusually large, long colon and inadequate bowel hygiene is a contributing factor.
Sigmoid volvulus: Volvulus occurs most commonly in the sigmoid. Obstipation, cramps, and marked abdominal distention are the usual complaints. Abdominal x-ray shows a large, distended colon. Distention may be limited lo the sigmoid loop but occasionally extends above the liver. A barium enema shows the typical bird-beak deformity at the level of the Iwist.
Usually, a long rectal tube can be passed through a sigmoidoscope (or eolonoscope) beyond the obstruction; this can produce explosive deflation. If deflation is incomplete or indications of gangrene are noted, immediate laparotomy is necessary. The colonoseope is useful in determining if gangrene is present.
If deflation occurs, resection of Ihe involved colonic segment is done electively during the same hospitalization, unless overriding reasons to defer surgery exist. If surgery is not performed, the probability of recurrence is very high.
Cecal volvulus: The cecum is another likely site for volvulus. Diagnosis is made on the basis of abdominal cramps, nausea, vomiting, distention, and obstipation. Abdominal x-ray shows a large gas bubble in Ihe midabdomen or the left upper quadrant. Barium enema shows the typical bird-beak deformity in Ihe ascending colon and no reflux into the

ileum. Gangrene .supervenes rapidly, so immediate surgery is essential. If no evidence of gangrene exists, the cecum tan be anchored by a cecostomy tube after the twist has been reduced. The alternative for low-risk patients is immediate resection and reanastomosis. When gan­grene occurs in a high-risk patient, resection and the formation of ileal and colonic fistulas is necessary. Intestinal continuity is reestablished later.

Ulcerative Colitis

(See also Ch. 55)

This disease is treated primarily by gastroenterologists. The major complications requiring surgery include failure to respond to medical therapy, hemorrhage, toxic megacolon, perforation, and late-developing cancer. Ulcerative colitis often pursues a more virulent course in pa­tients > 60 yr; with late onset, the mortality in severe cases is

In severe cases, medical therapy almost always includes corticoste­roids. However, these drugs increase the risk of spontaneous perfora­tion, which may be painless and diagnosed only when an upright ab­dominal x-ray shows subdiaphragmatic gas.

Surgery is usually a subtotal colectomy or a total proclocolectomy, both of which require a permanent ileostomy. The most common cause of mortalily is a long delay before surgery.

Patient follow-up after resection of colorectal cancer is not standardized. Nevertheless, the removal of all cancer and polyps from the bowel should be ascertained. Patients should be examined every 6 mo using rigid sigmoidoscopy, guaiac stool tests, and carcinoem-bryonic antigen (CEA) determinations. Anastomotic recurrences are most common after low rectal anastomoses and can be detected by rigid sigmoidoscopy. The best marker for recurrent colorectal cancer. CEA determinations are especially valuable postoperatively, when a rise above baseline usually indicates recurrence. Other recurrent can-cots, particularly those of Ihe rectum, may nol produce an elevated CKA level. Some patients can be cured by a second operation for a recurrcni  diagnosed by a rising CKA level. I”or at leas! *» yr, an annual colonoscopy *hou111 he performed. If il is not, an imiuial barium enema is indicated

Surgery of the Gastrointestinal Tract   755
Ch. 62
Palliative procedures: In many cases, only palliative procedures are possible, either initially or when cancer recurs. A colostomy may help relieve unremitting tenesmus. Radiation therapy can ease the pain of recurrent rectal cancer. Laser therapy has been used to reduce inoperable rectal tumors and prevent obstruction.
Prognosis: The crude 5-yr survival rale for colorectal cancer is aboul 50% to 55% in most major medical centers. When deaths from other causes are excluded, the adjusled 5-yr survival rate is 90% for class A disease, about 60% lo 70% for class B. 40% for class C, and < 20% for class D. Local recurrence of rectal cancer has been reduced significantly by preoperative and postoperative radiation and chemotherapy; in several rccenl studies, life expectancy has increased beyond that for patients treated by surgery alone.

The most common colorectal disorders requiring surgery in the elderly are cancer, volvulus, diverticular disease, and angiodysplasia. (Diverticular disease and angiodysplasia are discussed in Ch. 55.) Ulcerative colitis is an uncommon but serious problem.
Colorectal Cancer
(Sec also Ch. 6(»
Cancers of the colon and upper rectum preferably are treated by segmental resection and reanastomosis in a single operation. Multiple tumors may require subtotal colectomy. However, because low ileorectal anastomoses may lead to severe diarrhea in older patients, an adequate amount of large bowel should be left when possible. Preferably, wide excision of (he mesentery and regional lymph nodes is performed concurrently. The distal line of resection preferably should be at least 2 cm beyond the tumor.
Cancers of the middle and lower rectum are more problematic in the elderly because the operation most likely to cure—abdominoperineal resection with permanent colostomy—requires lifestyle changes that may be unsatisfactory to some patients. Fortunately, use of a stapling device permits anastomosis lower than is possible wilh hand-suluring techniques. However, the anal sphincter can be preserved in only about Wo of lower rectal cancers.Favorable cancers of the lower rectum can be treated with procedures other than proctectomy (eg, local excision, intracavitary radiation therapy, and electrocoagulation). In cases of carcinoma of the anal canal, remarkable local tumor control with chemoradiation therapy has been demonstrated.
Local excision is satisfactory for polypoid rectal lumors that are not fixed, not > 2 cm in diameter, and of low or moderate differentiation. Specimens must include the entire tumor and underlying rectal wall; the margins of the specimen must be free of cancer. In one series, recurrence was noted in only %% of cases. However, if the tumor is larger or attached to the underlying muscularis. the recurrence rate rises (about 23% in this study).
Papillon’s method of intracavitary radiation, in which about 150 Gy are delivered to the tumor through a special scope, was successful in his hands with small, polypoid, freely movable neoplasms. Others have found that attempts to extend Papillon’s method to the more common larger, fixed lumors is less effective and usually results in recurrence.
Electrocoagulation also may be effective for small lesions. However, according to one study, when it was used for cancers > 4 cm in diameter, the results were poor.
A combination of radiation therapy and surgical resection is helpful in many patients. Preoperative radiation allows many fixed and otherwise inoperable rectal cancers to be resected. For the usual reclal cancer, postoperative radiation reduces the local recurrence rate in Bz and C lesions; some studies have shown increased survival. Intraoperative radiation, although still investigational, appears lo have a favorable influence, particularly in reducing local recurrence.
Chemotherapy has proved valuable in reducing local recurrence of rectal cancer. Fluorouracil combined with radiation therapy is recommended. Adenocarcinoma of the colorcctum responds much less favorably than squamous cell cancer of the perianal area.
Immunotherapy has not played any significant role in the treatment of colorectal cancer.