Occult blood is blood in your feces that cannot be seen by the eye. It can be caused by bleeding in the body between your stomach and anus.
This test is done to find colon cancer at an early stage. It can also be used to find blood in your stool if you are having belly pain, diarrhea, vomiting, lack of hunger, or other problems.
The test may be needed as a routine screen for colon cancer for people who are at risk. Men and women should be screened every year after age 50. People with a personal or family history of polyps or colon cancer should be screened earlier.
The test may also be done if your doctor thinks that you have an intestinal infection or swelling.
A small sample of your stool is needed.
The sample can be taken by a doctor in the office or at home using a kit. The kit is the preferred method.
If your doctor takes the sample in the office, you will be asked to lower your pants and bend over. The doctor or nurse will wear gloves. A small sample of stool will be taken during a digital exam. This is a quick test with little pain.
You may also be given a kit to collect a sample at home. When you are ready to have a bowel movement, you will set up the kit according to the instructions. The kit should let you to collect 3 samples of stool within a week. Some kits have a disposable container into which you can pass your bowel movement. Other kits might have paper or plastic wrap that you can lay in the toilet to help keep your stool from getting in the water.
Use the thin wooden sticks in the kit to pick up a small amount of stool and smear it onto the card. People who do not have hemorrhoids may be allowed to smear the stool onto the card with stool from toilet paper. Seal and return the samples to the office.
You will not have any problems from this test.
It will take several days to get your results.
Only about half of colon cancer tumors shed enough blood to be found on this test. Blood in your stool can be from:
Talk to your doctor about your test results. A test may point to an illness that you do not have. It can also miss an illness that you may have. The doctor will check your symptoms and all test results before making a diagnosis.
Colorectal cancer screening. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T114074/Colorectal-cancer-screening. Updated November 30, 2018. Accessed May 21, 2019.
Last reviewed March 2019 by EBSCO Medical Review BoardJames P. Cornell, MD