Fecal Occult Blood (FOB)

The fecal occult blood test (FOBT) checks stool samples for hidden (occult) blood. Occult blood in the stool may indicate colon cancer or polyps in the colon or rectum — though not all cancers or polyps bleed. If blood is detected through a fecal occult blood test, additional tests such as a colonoscopy may help determine the source of the bleeding. The fecal occult blood test can only detect the presence or absence of blood — it can’t determine what’s causing the bleeding.