Precise diagnosis in severe hematochezia.

Angiography has clarified the origin of severe hematochezia in many cases. It has demonstrated the frequency of bleeding from colon diverticula on the right side, delineated new causes in occasional instances, eg, angiodysplasia, and underscored the fact that some patients in whom the clinical diagnosis is colonic bleeding may in fact be bleeding proximal to the colon. Although total colectomy has been widely accepted as the operation of choice, better results may be expected for many patients if the bleeding site is pinpointed and lesser resections done. In the case presented, colonoscopy identified the site of bleeding.