. The fecal occult blood (FOB) test is used to detect the presence of blood in the stool that cannot be seen with the naked eye.
. Occult blood in the stool is a symptom of gastrointestinal problems such as colorectal cancer, ulcers, polyps, colitis, diverticulitis, and fissures (although not all cases bleed).
. If the result is positive, additional tests such as a colonoscopy are needed to determine the source of the bleeding. This test only determines the presence of blood in the stool, not the cause of the bleeding.