Evaluation and Management of Gastrointestinal Bleeding Part 2: Lower and Obscure Gastrointestinal Bleeding

There are 20 cases of lower gastrointestinal (GI) bleeding per 100 000 adults annually in the United States. The incidence rate rises substantially with age, with a 200-fold increase between the 3rd and 9th decades of life. As with upper GI bleeding, there is spontaneous cessation of bleeding in 80% of cases. The mortality rate of 3% to 5% for lower tract bleeding is substantially lower than the rate for upper tract bleeding. A definitive source of the bleeding will not be found in a substantial number of patients. Obscure GI bleeding is defined as bleeding that persists or recurs and for which there is no obvious source found during routine endoscopic evaluation. It constitutes as much as 5% of all GI bleeding, and the small intestine is the most common site. Because the presentation is variable, obscure GI bleeding can be clinically evident, as in obscureovert bleeding (in which there is melena or hematochezia) or can present as obscure-occult bleeding, which is accompanied by recurrent iron deficiency anemia or a persistently positive fecal occult blood test. Patients with obscure GI bleeding often require multiple hospitalizations and transfusions, and they typically undergo extensive and repeated diagnostic workups.