Melena is best described as which of the following?

• A. Bright Red Blood in Stool
• B. Black Tarry Stool
• C. Pale, Clay-Colored Stool
• D. Loose Stools With Mucus

Answer: (B)

Melena signals upper GI bleeding. When blood enters the digestive tract and remains there long enough to be digested, gastric acids and bacterial action convert it into a dark, tarry form. This results in a stool that is black, sticky, and often has a foul odor. The coloration indicates the blood has been in the gut long enough for digestion, which is typical of upper GI sources like ulcers or varices, rather than a rapid bleed elsewhere.

In contrast, bright red blood in the stool points to a lower GI source or rapid transit, pale, clay-colored stools suggest biliary obstruction with little bile entering the gut, and loose stools with mucus describe diarrhea with mucus rather than blood staining. Thus, black tarry stool best describes melena.