Obscure gastrointestinal bleeding (OGIB) is defined as bleeding of unknown origin that persists or recurs after an initial negative endoscopic evaluation including colonoscopy and/or upper endoscopy (esophagogastroduodenoscopy [EGD]). OGIB can be classified as either: (1) occult OGIB, which is manifested by recurrent iron deficiency anemia and/or recurrent positive fecal occult blood test (FOBT) results; or (2) overt OGIB, which is manifested as melena or hematochezia.
Angioectasias of the small bowel are the most common source of OGIB in the elderly and account for 30% to 40% of gastrointestinal bleeding in this population, whereas tumors such as leiomyomas, carcinoids, lymphomas, and adenocarcinomas are the predominant cause in patients aged 30 to 50 years. Meckel's diverticulum is also a potential cause of bleeding and should be considered in the differential diagnosis. Erosions and ulcers from nonsteroidal anti-inflammatory drug (NSAID) use and Crohn's disease of small bowel are also potential causes of OGIB. Overall, OGIB accounts for 5% of all cases of gastrointestinal hemorrhage.
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Cite this: Obscure Gastrointestinal Bleeding -- The Role of Endoscopy - Medscape - May 11, 2006.