Black stools, or melena, typically indicate which type of GI bleeding?

• A. Upper GI bleeding
• B. Lower GI bleeding
• C. Kidney disease
• D. Pulmonary embolism

Answer: (A)

Melena is produced when swallowed blood has spent enough time in the GI tract to be digested and oxidized, turning the stool into a dark, tarry color. This pattern points to bleeding in the upper GI tract, such as from the stomach or proximal small intestine, where gastric acid and enzymes alter the blood as it passes through. Lower GI bleeding, by contrast, tends to produce bright red or maroon stools because the blood has less chance to be digested before elimination. Conditions like kidney disease or a pulmonary embolism don’t cause this black, tarry stool pattern. So, the presence of black stools typically signals upper GI bleeding.