A fecal occult blood test looks for blood in a sample of stool. It can find tiny amounts of blood that can't be seen just by looking at the stool. The medical term for this hidden blood is occult blood. A fecal occult blood test is often shortened to FOBT.
A fecal occult blood test is one option for colon cancer screening in people who don't have any symptoms. Occult blood in the stool may be a sign of cancer or polyps in the colon or rectum. Polyps are growths of cells that aren't cancers but could become cancers. Not all cancers or polyps bleed.
If a fecal occult blood test finds blood, more tests may be needed to find the source of the bleeding. The fecal occult blood test only can detect if blood is present or not present. It can't find the source of the bleeding.
A fecal occult blood test shouldn't be used if you have colon cancer symptoms. These symptoms may include blood in your stool or in the toilet, pain in your abdomen, and a change in bowel habits. This test also isn't used in people with a high risk of colon cancer. This includes those who have a history of colon polyps and those with a close family member who has had colon cancer. Talk with your healthcare team about your symptoms and health history if you are considering colon cancer screening.
Blood in your stool means there is bleeding in the digestive tract.