Colonic diverticular bleeding is the most common cause of overt lower gastrointestinal bleeding in adults. In most cases, the bleeding will stop spontaneously. However, if the bleeding persists, endoscopic, radiologic, or surgical intervention may be required.
This topic will review colonic diverticular bleeding. The general approach to lower gastrointestinal bleeding, the causes of lower gastrointestinal bleeding, and the evaluation of obscure gastrointestinal bleeding are discussed elsewhere. (See "Approach to acute lower gastrointestinal bleeding in adults" and "Etiology of lower gastrointestinal bleeding in adults" and "Evaluation of obscure gastrointestinal bleeding".)
Colon carcinoma is the most common source of lower gastrointestinal blood loss, but the bleeding is often occult (ie, no evidence of visible blood loss to the patient or clinician). On the other hand, colonic diverticular bleeding is the most common cause of brisk hematochezia (maroon or bright red blood), accounting for 30 to 50 percent of cases of massive rectal bleeding [1-3]. (See "Angiodysplasia of the gastrointestinal tract" and "Complications of hemodialysis in the older patient".)
Among patients with diverticulosis, bleeding will occur in approximately 15 percent and will be massive in a third . Interestingly, obesity appears to increase the risk of diverticulitis and colonic diverticular bleeding .
A characteristic angioarchitecture is associated with bleeding colonic diverticula (figure 1) . As a diverticulum herniates, the penetrating vessel responsible for the wall weakness at the point of herniation becomes draped over the dome of the diverticulum, separated from the bowel lumen only by mucosa (picture 1). Over time, the vasa recta is exposed to recurrent injury along its luminal aspect, leading to eccentric intimal thickening and thinning of the media. These changes may result in segmental weakness of the artery, predisposing to rupture into the lumen. It is rare for bleeding to coexist with diverticulitis . (See "Colonic diverticulosis and diverticular disease: Epidemiology, risk factors, and pathogenesis".)