A positive fecal occult blood test indicates that red blood cells were found during the stool examination, proving that the stool was mixed with blood. Where does the blood come from. It usually indicates bleeding from the gastrointestinal tract, usually upper and lower gastrointestinal bleeding. If the stool is black in color or thin, tarry stool with a high frequency, upper gastrointestinal bleeding is often considered. If there is fresh blood or mucous jelly-like pus and blood on the surface of the stool, it indicates lower gastrointestinal bleeding, and it is common to see a positive occult blood test for ulcers in the gastrointestinal tract, frictional bleeding from polyps, or anal fissures or hemorrhoids. However, the specific disease for which a positive fecal occult blood test is indicated requires further gastroscopic examination and perianal finger examination.