Obscure gastrointestinal bleeding (OGIB) is defined as gastrointestinal bleeding from a source that cannot be determined even after upper or lower gastrointestinal endoscopy is performed. It is an intractable disease that can cause repeated bloody stools and anemia without an identifiable cause, and may require frequent blood transfusions. Although the pathogenesis of OGIB remains largely unclear, it is assumed that in most cases, the bleeding is from the small intestine.