Assertion: bleeding | /r/AtLocation | the stomach
Facets:
Source sentences:
text: Melena mostly occurs when the bleeding is in the stomach where the blood is exposed to acid or is in the small intestine for a prolonged amount of time; however, melena also may occur with bleeding from the colon if the transit of the blood through the colon is slow, and there is enough time for the intestinal bacteria to break the blood down into chemicals (hematin) that are black.