part of part of has part has part characteristic of inheres in has modifier Gastrointestinal hemorrhage Melena SNOMEDCT_US:267055007 SNOMEDCT_US:2901004 The passage of blackish, tarry feces associated with gastrointestinal hemorrhage. Melena occurs if the blood remains in the colon long enough for it to be broken down by colonic bacteria. One degradation product, hematin, imbues the stool with a blackish color. Thus, melena generally occurs with bleeding from the upper gastrointestinal tract (e.g., stomach ulcers or duodenal ulcers), since the blood usually remains in the gut for a longer period of time than with lower gastrointestinal bleeding. SNOMEDCT_US:269899009 UMLS:C0025222 SNOMEDCT_US:35064005 UMLS:C0474585 HP:0002249 Black faeces SNOMEDCT_US:249627005 Black feces Bloody diarrhea abnormal increased amount blood feces