What does melena refer to?

Melena specifically refers to black, tarry-like stool resulting from bleeding in the upper gastrointestinal tract. The characteristic color and texture of the stool are caused by the digestion of blood as it passes through the gastrointestinal system, leading to the dark coloration that resembles tar.

Understanding the significance of melena is important in clinical practice, as it often indicates potential conditions such as peptic ulcers, variceal bleeding, or other serious gastrointestinal issues that require prompt medical evaluation. The black color signifies that the blood has been present in the digestive tract long enough for it to undergo a chemical change, which is why it’s distinct from other types of blood in stool. This differentiates melena from bright red blood in stool, which typically originates from lower gastrointestinal bleeding, or liquid stool, which is more associated with diarrhea, and does not indicate the same underlying issues.