Fecal occult blood test

Definition
By Mayo Clinic staff

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.
Why it's done

*
See Also
Hand Scheduled
Related Links
* Section Focus Colon cancer
* Colon polyps
* Peptic ulcer
* Colonoscopy

Related Guides

References

1. Levin B, et al. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: A joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology. 2008;134:1570.
2. Hundt S, et al. Comparative evaluation of immunochemical fecal occult blood tests for colorectal adenoma detection. Annals of Internal Medicine. 2009;150:162.
3. Fecal occult blood test: The test sample. American Association for Clinical Chemistry. http://www.labtestsonline.org/understanding/analytes/fecal_occult_blood/sample.html. Accessed March 12, 2009.
4. Fecal occult blood test: The test. American Association for Clinical Chemistry. http://www.labtestsonline.org/understanding/analytes/fecal_occult_blood/test.html. Accessed March 12, 2009.
5. Bynum TE. Evaluation of occult gastrointestinal bleeding. http://www.uptodate.com/home/index.html. Accessed March 12, 2009.
6. Pignone M, et al. Meta-analysis of dietary restriction during fecal occult blood testing. Effective Clinical Practice. 2001;4:150.
7. Van Rossum LG, et al. Random comparison of guaiac and immunochemical fecal occult blood tests for colorectal cancer in a screening population. Gastroenterology. 2008;135:82.

MY00620

June 20, 2009

© 1998-2010 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "EmbodyHealth," "Enhance your life," and the triple-shield Mayo Clinic logo are trademarks of Mayo Foundation for Medical Education and Research.