The existence of blood in the feces that is not apparent to the unaided eye, yet can be identified through chemical examinations.
Tests for fecal occult blood are extensively utilized for colon cancer screening. The discovery of fecal occult blood can also serve as an indicator for various gastrointestinal disorders, including esophagitis (inflammation of the esophagus), gastritis (inflammation of the stomach lining), stomach cancer, intestinal cancer, rectal cancer, diverticular disease (formation of pouches in the intestinal wall), colon polyps, ulcerative colitis (inflammation and ulcers in the colon and rectum lining), or irritation of the stomach or intestine caused by medications like aspirin.