Fecal Occult Blood Test (FOBT) Test
A fecal occult blood test (FOBT) checks for hidden blood in your stool, which can be a sign of bleeding in your digestive tract. It is often used to screen for colorectal cancer.
What this test measures
The test measures the presence of hidden (occult) blood in a stool sample. Blood in the stool can indicate bleeding in the digestive tract, which may be caused by conditions such as polyps, hemorrhoids, diverticulosis, ulcers, inflammatory bowel disease, or colorectal cancer.
What your results mean
Reference ranges vary by laboratory and by your age and sex. MedlinePlus does not publish a single normal range for this test — always read your result against the range printed on your own lab report and discuss it with your provider.
Higher-than-normal results
According to MedlinePlus, if your results show blood in your stool, it means you likely have bleeding somewhere in your digestive tract. This could be due to conditions such as ulcers, hemorrhoids, polyps, benign tumors, or colorectal cancer.
Frequently asked questions
What does a fecal occult blood test check for?
It checks for hidden blood in your stool that you cannot see with your eyes.
Why is this test done?
It is commonly used to screen for colorectal cancer before you have symptoms. It may also help find other causes of gastrointestinal bleeding or anemia.
Does a positive result mean I have cancer?
No. According to MedlinePlus, blood in the stool can be caused by many conditions, including ulcers, hemorrhoids, polyps, and benign tumors. More tests are needed to find the exact cause.
What happens if my test shows blood in my stool?
Your provider will likely recommend more tests, such as a colonoscopy, to find the location and cause of the bleeding.
Can this test diagnose a condition on its own?
No. MedlinePlus states that a fecal occult blood test alone cannot diagnose any condition. It is a screening tool that requires follow-up testing.
Related lab tests
Sources
- MedlinePlus: Fecal Occult Blood Test (FOBT) — NIH MedlinePlus
Last updated . Information is aggregated from official public sources and is not a substitute for professional medical care.