Melaena Causes Diagnoses Management TeachMeSurgery Melaena appearance, causes, mechanism, sign value There are no 50 shades of melena, only one color: Black; and it's a color that smells bad. Otherwise it's not melena or it's derivatives (melenic, melanotic, melenatonic ) Great thread w a 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, Melena: What Is It, Causes, Symptoms, Bleeding, Treatment, and More Osmosis