DefinitionGastrointestinal (GI) bleeding refers to any bleeding that starts in the gastrointestinal tract, which extends from the mouth to the anus.The amount of bleeding can range from nearly undetectable to acute, massive, and life threatening.Bleeding may come from any site along the GI tract, but is often divided into:Upper GI bleeding: The upper GI tract is located between the mouth and the upper part of the small intestine.Lower GI bleeding: The lower GI tract is located between the upper part of the small intestine and the anus. The lower GI tract includes the small and large bowels.Alternative NamesLower GI bleeding; GI bleeding; Upper GI bleedingConsiderationsGI bleeding can range from microscopic bleeding (the amount of blood is so small that it can only be detected by laboratory