Medical Tests
Information on medical tests, including how to prepare, what to expect, and what the results mean.

Fecal Occult Blood Test (FOBT)

What To Think About

• A fecal occult blood test (FOBT) is most often used as a screening test. By itself, an FOBT is not used to diagnose colon polyps or colorectal cancer. FOBT is a more effective screening test if it is done every year. If an FOBT finds blood in the stool, you may need more tests, such as a rectal exam, colonoscopy, barium enema, or endoscopy. For more information, see the medical tests Digital Rectal Examination (DRE), Colonoscopy, Barium Enema, Upper Gastrointestinal Endoscopy, Sigmoidoscopy (Anoscopy, Proctoscopy), and Computed Tomography Colonography (CTC).
• An FOBT has a high rate of false-positive results. This means that the test may be positive when you do not have a polyp or cancer. This can occur because the blood comes from another source, such as from hemorrhoids. Tests, such as a colonoscopy, may be done to find the cause of the positive FOBT and to rule out cancer.
• People ages 50 to 80 who have an FOBT every year are less likely to die of colorectal cancer than people who do not have regular FOBTs.²
• There are other tests where you don't need to limit what you eat prior to the test. Also, you may not need to provide as many stool samples. These tests are called the immunochemical Fecal Occult Blood Test (iFOBT) or the Fecal Immunochemical Test (FIT).
• Which screening test you choose depends on your risk, your preference, and your doctor. Talk to your health professional about your risk factors and what test is best for you.

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