Exsanguinating hemorrhage from the colon in adults is caused by diverticular disease, angiodysplasia, solitary ulcer, ulcerative colitis, ischemic colitis, or a variety of uncommon lesions such as coagulation disorders, radiation injury, chemotherapeutic toxicity, and others. Bleeding occurs in the right colon about as often as in the left colon, probably because angiodysplasias are more prominent on the right side, but right-sided diverticula can also bleed. Bleeding lesions in the small intestine are rare and include hereditary hemorrhagic telangiectasia.
Chronic rectal bleeding, typically seen in patients with cancer, polyps, hemorrhoids, fissures, and other conditions, does not require emergent evaluation. Anorectal examination, colonoscopy, and x-rays if indicated can be performed electively. Acute severe hemorrhage, however, is a potentially life-threatening problem, and prompt evaluation and treatment are critical. Some patients bleed rapidly, but the bleeding stops spontaneously after only a small amount of blood is lost, and these patients are never in danger. Usually, however, one cannot be sure that bleeding will not recur, so this type of bleeding must be taken seriously too, which means that aggressive evaluation is needed.
Treatment of Acute Lower Gastrointestinal Hemorrhage
A plan of management of acute lower gastrointestinal hemorrhage – many decisions depend on the rate of bleeding, which is difficult to include in an algorithm. Bleeding stops spontaneously in 90% of patients before transfusion requirements exceed two units.
The patient with severe rectal bleeding is resuscitated with intravenous fluids and transfusions while the diagnostic procedures are begun. Clotting parameters should be measured and deficits corrected, and associated medical conditions should be identified and treated as soon as possible. Digital rectal examination, anoscopy, sigmoidoscopy should be performed with no attempt to prepare the bowel. If a bleeding lesion is found in the anorectum, it should be treated. Examples include hemorrhoids, polypoid neoplasm, and ulcerative proctitis.
A nasogastric tube should be inserted and the aspirate inspected for bile, gross blood, and occult blood. Blood in the stomach is an indication of bleeding from a site proximal to the ligament of Treitz — and esophagogastroduodenoscopy is performed. Occasionally, a patient bleeds from the duodenum but blood does not reflux back into the stomach; bile in the nasogastric aspirate would seem to eliminate this possibility, but in the absence of blood or bile, esophagogastroduodenoscopy should be done.
If esophagogastroduodenoscopy is negative and bleeding has presumably stopped or continues at a slow rate, the colon can be prepared and colonoscopy performed within a few hours. The bleeding site is identified in 25–94% of cases, depending in part on skill, experience, and, very importantly, the criteria for inclusion of a patient in this category of bleeding. Some bleeding lesions can be treated colonoscopically with a bipolar probe, heater probe, or laser. Colonoscopy with negative results probably means that bleeding has stopped. Barium enema discloses abnormalities such as diverticula but does not reveal which lesions have been bleeding.
The optimal method for evaluating patients who are bleeding rapidly is controversial, and the decision may hinge on available resources. A radionuclide “bleeding” scan after injection of 99m Tc-labeled red blood cells may show whether bleeding persists and can detect a 0.1 mL/min rate of bleeding. Localization of bleeding is not reliable, but valuable information may be obtained. Angiography is seldom successful in demonstrating an active bleeding site if the bleeding scan is negative, so colonoscopy should be undertaken. Active bleeding shown on radionuclide scan should be followed by angiography.
Selective mesenteric angiography identifies the bleeding site in 14–70% of patients (threshold 0.5 mL/min); here, too, enthusiasm of the angiographer is important. If the bleeding site is seen, intra-arterial infusion of vasopressin controls bleeding, at least transiently, in 35–90% of patients. Definitive treatment with highly selective arterial embolization may be performed with success in 75% of patients.
The other option for rapid bleeding is emergency colonoscopy without preliminary bowel cleansing. Blood is a cathartic, and the colon may be free of stool. Even so, colonoscopy in this situation is difficult. Experts are able to see the bleeding point in up to 50% of patients, and in 70% of cases bleeding can be localized to one region. Endoscopic therapeutic measures can be applied in up to 40% of patients, with success in half of them.
Operation is indicated for bleeding that persists or recurs despite angiographic and endoscopic therapeutic maneuvers. Operation is advisable also in good-risk patients who have stopped bleeding if the bleeding source is known and cannot be managed in some other way (eg, colonoscopic coagulation). Operation is limited to segmental colonic resection if the bleeding site has been localized conclusively. More extensive resection is usually warranted in patients who are bleeding from the right colon and have multiple diverticula in the left colon. If the surgeon has no preoperative localizing data and intraoperative examination is unrevealing, the stomach, small bowel, and colon can be endoscoped during the procedure to search for the source of blood. If all localizing efforts fail and the colon is the likely bleeding site, total abdominal colectomy (usually with primary anastomosis) may be the only recourse. Fortunately, extensive “blind” colectomy is seldom required today.
The mortality rate from lower gastrointestinal hemorrhage is about 10–15%.