Final answer:
Tarry stools are black and sticky in appearance, indicating the presence of digested blood due to bleeding in the upper gastrointestinal tract.
Step-by-step explanation:
When a physician mentions that a patient has a history of tarry stools, it refers to stools that are black and sticky in appearance. This can indicate the presence of digested blood in the stool, which is often caused by bleeding in the upper gastrointestinal tract, such as the stomach or the first part of the small intestine. The dark color is due to the breakdown of hemoglobin from the blood.