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Fecal Occult Blood Test

  • Cynthia M. Johnson, MA
Publication Type:


Fecal Occult Blood Test

(FOBT; Stool Occult Blood Test)


A fecal occult blood test (FOBT) looks for blood in the stool.

Reasons for Test

The test is done to screen for colon and rectal cancers. It may also be done to look for causes of belly pain, diarrhea, vomiting, or lack of hunger.

Colon Cancer in the Rectal Wall.

Rectal cancerhttp://services.epnet.com/getimage.aspx?imageiid=72937293si2003.jpgsi2003.jpgNULLjpgsi2003.jpgNULL\\hgfiler01a\intellect\images\si2003.jpgNULL85NULL2008-11-07292400Copyright © Nucleus Medical Media, Inc.

Possible Complications

There are no major problems linked to having this test.

What to Expect

Problems To Look Out For

Call your doctor if you have new or worsening symptoms.

If you think you have an emergency, call for medical help right away.

Prior to Test

Your care team may meet with you to talk about:

  • Current medicines, herbs, and supplements that you take and whether you need to stop taking them before the test
  • Avoiding certain foods in the days leading up to the test
  • Not having the test during a menstrual cycle
  • Waiting until any hemorrhoids that you may have are no longer bleeding
  • Not using toilet bowl cleaners in the days before taking the test




  • Cobo-Cuenca, A.I., Laredo-Aguilera, J.A., et al. Temporal trends in fecal occult blood test: associated factors (2009-2017). International Journal of Environmental Research and Public Health, 2019; 16 (12): 2120.
  • Colorectal cancer screening. EBSCO DynaMed website. Available at: https://www.dynamed.com/prevention/colorectal-cancer-screening.
  • Colorectal cancer screening tests. American Cancer Society website. Available at: https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/screening-tests-used.html.
  • Fecal occult blood tests. Cancer.Net website. Available at: https://www.cancer.net/navigating-cancer-care/diagnosing-cancer/tests-and-procedures/fecal-occult-blood-tests.


  • Marcin Chwistek, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.