My Crohnstipated Life

The fecal occult blood test — also known as FOBT — is a lab test used to check 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. Typically, occult blood is passed in such small amounts that it can be detected only through the chemicals used in a fecal occult blood test.

If blood is detected through a fecal occult blood test, additional tests may be needed to determine the source of the bleeding. The fecal occult blood test can only detect the presence or absence of blood. The fecal occult blood test doesn’t indicate potential sources of bleeding.