What does dark, tarry stool indicate?

Dark, tarry stool indicates melena, which is the medical term for gastrointestinal bleeding that has occurred in the upper GI tract, such as the stomach or small intestine. When blood from the upper GI tract is digested, it takes on a dark color as it passes through the intestines, resulting in the characteristic tarry appearance of the stool. This condition may signal a more serious underlying issue, such as a peptic ulcer or esophageal varices, and requires further evaluation.

The other options relate to different medical signs or conditions. Rectal tone is a measure of the muscle control in the rectum, Cullen's Sign refers to bruising around the umbilical area associated with intra-abdominal bleeding, and adnexal tenderness is related to pain or tenderness in the adnexal areas of the female reproductive system, typically assessed during a pelvic examination. These conditions do not pertain to the color or consistency of stool.