Fecal occult blood test

Fecal occult blood test (FOBT) is a medical 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.

Overview

Typically, occult blood is passed in such small amounts that it can be detected only through the chemicals used in a FOBT. If blood is detected through a FOBT, additional tests may be needed to determine the source of the bleeding. The FOBT is the most commonly used test for detecting colorectal cancer, but it can also detect blood from any point in the digestive tract.

Procedure

The FOBT requires the collection of three stool samples that are then sent to a doctor or a laboratory for testing. The samples are applied to special cards and returned to the doctor or laboratory for testing. A positive test result indicates that abnormal bleeding may be occurring somewhere in the digestive tract.

Risks and Limitations

While the FOBT can only detect the presence or absence of blood, it does not indicate the source of bleeding or whether or not cancer is present. Therefore, a positive FOBT result often requires further investigation with more specific tests. Moreover, the FOBT can sometimes give false-positive or false-negative results.

See Also

• Colonoscopy
• Colorectal cancer
• Digestive tract
• Polyps

References

Fecal occult blood test Resources
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