fecal occult blood test

A test that checks for occult (hidden) blood in the stool. A small sample of stool is placed in a special collection tube or on a special card and sent to a doctor or laboratory for testing. Blood in the stool may be a sign of colorectal cancer or other problems, such as polyps, ulcers, or hemorrhoids. Guaiac fecal occult blood test and immunochemical fecal occult blood test are two types of fecal occult blood tests. Guaiac fecal occult blood test uses a chemical substance called guaiac to check for blood in the stool. Immunochemical fecal occult blood test uses an antibody to check for blood in the stool. Also called FOBT.