Frequently Asked Questions About the Fecal Occult Blood Test (FOBT)


What if my healthcare provider has never suggested a FOBT?

Adults ages 50 years and older should have tests to check for colorectal cancer on a regular basis. FOBT is one test that you could do to check for colorectal cancer and it should be done every year.


Since there are other tests that check for colorectal cancer, it is possible that your healthcare provider recommended one of the other tests. You might decide that FOBT is a better test for you, once you learn that it is an option.


If you are up to date with another screening test, it is possible that this one has not been suggested to you yet because you don’t need to be screened right now.


As you get older, you have more health concerns. Your doctor has a lot to talk to you about. If your doctor does not mention getting tested for colon cancer or told you about FOBT, don’t be afraid to ask about it.

Do I have to change my diet?

Depending on the type of FOBT kit you are given, you may or may not  need to change your diet.  Talk to your healthcare provider to see if you need to change your diet before doing the FOBT.

Do I have to stop taking medication?

No, in general you should not stop taking your medications; however, taking aspirin or blood thinners could lead to an abnormal (positive) test.  Tell your doctor about all the medications you are taking.

How do I store/keep my stools stool samples in the house?

Depending on the type of FOBT kit you are given, you will need to collect 1 to 3 consecutive stool samples, so the stool samples you collect will not need to be in your house for very long.


Very little stool is needed for each sample and each area where you place your stool sample is covered by a cardboard flap, or sealed in the sample tube


The FOBT kit comes with a foil-lined mailing envelope where you can keep your card or tube until it is ready to be mailed.

Are there times when I should not have FOBT?

There might be times that you should not have an FOBT. For example if you are experiencing symptoms of colorectal cancer, you should talk to your doctor before doing FOBT. FOBT is not recommended for people who have a family history of colorectal cancer (first degree relative – mother, father, sister, or brother – diagnosed before 60 years of age, or two first degree relatives diagnosed at any age), and for other people who are increased risk of developing colorectal cancer.

What do I do if the test is positive?

If the test is positive (abnormal), you will need to have a colonoscopy to determine what is causing the blood in your stool.


It is possible that you will have an abnormal test, but do not have cancer. For example, 5 out of 100 people who has had FOBT will have a positive result when they do not have cancer.


If the FOBT is positive it could be from a bleeding polyp. During the follow-up colonoscopy most polyps can be found and removed.

Does a negative result mean I do not have colorectal cancer?

A negative (normal) result means that your stool did not have any blood. However, these tests are not able to detect polyps or colorectal cancers that are not bleeding.  It is possible that a negative result might have happened even if someone really does have a polyp or colorectal cancer (link to false negative pictograph).


For example, 13 out of every 100 people who have FOBT will have a negative (normal) result when they do have cancer (false negative).

Is the stool test my doctor did in the office the same as FOBT for colorectal cancer screening?

No, that test is not the same as a FOBT to check for cancer. The FOBT you do for colorectal cancer screening is done in the privacy of your own home.

How long do I have to wait to get my test results?

Ask your healthcare provider how long they expect it will take to receive your test results from the laboratory. Also, when you get results, make sure to ask about your follow-up plan.

Does insurance cover the cost of FOBT?

Colorectal cancer screening is covered by most insurance plans and Medicare.  Check with your insurance provider or Medicare (1-800-MEDICARE) to find out which tests are covered for you.

How are the two types of FOBT tests similar and different?

There are two different Fecal Occult Blood Tests (FOBTs). Both look for hidden blood in the stool and both are done at home. Below is a table that describes the differences between the two tests:

Test How the test works Preparation Number of Samples
1-sample FOBT
  • Looks for hidden blood in the stool using a protein found in the blood.
  • The test only finds protein from human blood.
  • Requires only one sample
  •  No dietary restrictions
  • Requires a sample from one bowel movement
3-consecutive sample FOBT
  • Looks for hidden blood in the stool using a protein found in the blood.
  • The protein is not only from human blood.
  •  Certain foods must be stopped before the test
  • Requires a sample from three consecutive bowel movements


There are also some similarities between the two FOBTs:


  • Both tests are a less expensive option than colonoscopy to test for colorectal cancer
  • Both tests are covered by Medicare
  • Aspirin use must be avoided either type of FOBT to decrease the chance that the test will come back positive when in fact there is no blood in the stool from a polyp or colorectal cancer (false positive)
  • Both tests can be done at home