What is the role of ischemic colitis in the etiology of lower gastrointestinal (GI) bleeding?

Updated: Jul 26, 2019
  • Author: Burt Cagir, MD, FACS; Chief Editor: BS Anand, MD  more...
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Answer

Ischemic colitis is rarely a cause of significant blood loss; thus, large-volume or brisk bleeding should prompt a search for an alternate etiology. Tissue injury is typically caused by hypotension and vasoconstriction, which leads to mucosal friability and endoscopic findings often resembling the changes of IBD. Ischemic colitis usually involves the left side of the colon with rectal sparing. Elderly patients with comorbidities, such as heart failure and arrhythmia, are more susceptible.

Radiation therapy can cause inflammatory changes in the bowel resulting in mucosal telangiectasias that bleed. When this treatment is used for abdominal and pelvic cancers, bleeding due to mucosal damage in the colon can lead to complications of acute colitis or ulceration. Complications can occur early or late, with a median time of occurrence from 9 to 15 months. Risk factors for radiation-induced LGIB include arteriosclerosis and concomitant chemotherapy.

Other vasculitic entities, such as polyarteritis nodosa and Wegener granulomatosis, can also cause LGIB because of the underlying necrotic process that causes sloughing of the mucosa. Bleeding may also occur secondary to immunosuppressive therapy, which can cause thrombocytopenia. Aortocolonic fistulas, which rarely develop after aortic-graft surgery, can cause LGIB as long as 10-20 years after surgery.


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