Fecal Occult Blood Test (FOBT): Why It Is Done

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Why It Is Done

A fecal occult blood test (FOBT) is done:

• To find the presence of blood in the stool. Blood in the stool may be caused by hemorrhoids, anal fissure, colon polyps, colorectal cancer, and many other conditions that cause bleeding in the gastrointestinal tract.
• As a screening test for cancer of the colon and rectum (colorectal cancer). FOBT is a useful tool to screen for colorectal cancer because tissue or polyps with cancer changes are more likely to bleed than normal colon tissue. Polyps and cancers generally grow slowly and they may not bleed all the time. Sometimes blood in the stool is the only symptom of colorectal cancer. An FOBT helps find blood in the stool. More tests will need to be done to diagnose the cause of the bleeding. It is important to call your health professional if a home test shows blood in your stool. A home fecal occult blood test does not replace the need for a regular examination by your health professional.
• To help find the cause of abdominal pain.
• To check for the cause of anemia.
• As part of a routine physical examination for those with a higher chance of developing colorectal cancer, especially at age 50 and older.

Last updated:	August 11, 2008
Author:	Monica Rhodes
Reviewed By:	Kathleen Romito, MD - Family Medicine, Peter J. Kahrilas, MD - Gastroenterology
Editors:	Kathleen M. Ariss, MS, Tracy Landauer