GASTROINTESTINAL HEMORRHAGE (2): Melena. Melena, the passage of black, tarry stools, usually implies blood loss greater than 500 ml originating anywhere between the oropharynx and the right hemicolon. Melena occurs most often, Stool Colors and What They Can Tell You Your stool color can carry important clues about digestion, diet, or even disease. Most shades are harmless, but some changes signal the need for Melena an overview ScienceDirect Topics Your Poop Is Talking .. Are You Listening? Your stool is your gut's daily report card. The shape, color, and texture tell you exactly what's going on inside. Here's a quick doctor style