Most etiologies are self-limited and benign.
A complete history often can identify a presumptive bleeding source and direct an efficient workup. Ask about acuteness or chronicity of bleeding, color and quantity of the blood in stool or emesis, antecedent symptoms, history of straining, abdominal pain, or trauma. Anorectal disorders, fissures, and distal polyps produce bright red blood. Massive upper GI bleeding can produce bright red blood per rectum if GI transit time is rapid. Bleeding proximal to the ligament of Treitz usually produces melena instead of bright red blood.