Acute lower gastrointestinal (GI) bleeding includes a wide clinical spectrum, ranging from minute bleeding to massive hemorrhage with hemodynamic instability. Lower GI bleeding is approximately one fifth as common as upper GI bleeding and accounts for approximately 20 to 33 hospitalizations per 100,000 adults per year.[1] [2] The incidence of lower GI bleeding increases with age.
In developed countries, common causes of acute lower GI bleeding resulting in significant blood loss include colonic diverticular disease and angiodysplasia. Patients with severe bleeding or significant comorbid states require rapid identification and aggressive resuscitation. Hemodynamically insignificant bleeding may frequently result from hemorrhoids and colonic neoplasms. Rare causes of bleeding include solitary rectal ulcer, vasculitis, and endometriosis. Fifteen percent (15%) of patients who present with lower GI bleeding have an upper GI source following investigation.[3][4] The source of lower GI bleeding cannot be definitively identified in up to 25% of patients.[5][6]
Colonoscopy is the mainstay of the evaluation in patients in whom anorectal or upper GI causes have been ruled out. This is performed to localize the bleeding source and to enable hemostasis. Endoscopic hemostasis is successful in most cases.
Modalities including computed tomography (CT) angiography, catheter angiography, and radionuclide imaging may have a role in specific clinical scenarios.
