What is melena?

Blood in stool: Melena is dark, tarry, bowel movement with a characteristic odor that comes about from digested blood in the stool. Classically considered a sign of an "upper GI bleed, " (a bleeding ulcer or other bleeding from the mouth, esophagus, stomach, or duodenum), it can occur also from bleeding from the small intestine or even the right side of the colon. It always warrants prompt medical attention.

Melena: Is tarry black stool as a result of gastric bleeding and exposure of the blood to gastric acids. This should not be ignored!

Blood in stool: Melena means dark blood in the stool, usually coming from before the large intestine. Hematochezia is bright red blood in the stool, usually coming from somewhere lower in the GI tract. Either should be evaluated by a physician.

Black stool: Black tarry stool secondary to blood in the gastrointestinal tract. Usually from the stomach or duodenum, but may be due to bleeding further down (small bowel, colon).