Notice: Users may be experiencing issues with displaying some pages on stanfordhealthcare.org. We are working closely with our technical teams to resolve the issue as quickly as possible. Thank you for your patience.
Most colon polyps are found during tests for colorectal cancer. Unless the polyps are large and cause bleeding or pain, the only way to know if you have polyps is to have tests that explore the inside of your colon.
Several tests can be used to detect colon polyps. The tests may be used to screen for colon polyps and colorectal cancer. They can also be used as follow-up tests after colon polyps have been removed. There are two basic types of tests—stool tests and tests that look inside your colon.
These tests include:
Fecal immunochemical test (FIT).
This test is done to look for microscopic amounts of blood in the stool. There aren't any restrictions on what you can eat before having this test. If the test is positive for blood in the stool, you will need to have a colonoscopy. This will help your doctor find the source of the blood and remove polyps if they are found.
Fecal occult blood test (FOBT).
This test also looks for blood in the stool. But it isn't as specific as the FIT. There are restrictions on what you can eat before having this test. If this test is positive for blood in the stool, you will need to have a colonoscopy.
Stool DNA test (sDNA/Cologuard).
This test looks at DNA in the stool to see if there are changes in the cells of the colon. Certain kinds of changes in cell DNA happen when you have cancer. If your test is abnormal, you will need to have a colonoscopy.
An abnormal result from a stool test doesn't mean that you have colorectal cancer. It might be a false-positive result. So the next step is to have a colonoscopy. After you've had it, you and your doctor will know whether or not you have cancer.
Tests that look inside your colon
These tests include:
It allows the doctor to look at the lower third of the colon. During a sigmoidoscopy exam, samples of any growths can be collected (biopsy). And precancerous and cancerous polyps can sometimes be removed. But if your doctor finds polyps, you will need to have a colonoscopy to check the upper part of your colon.
It lets the doctor inspect the entire colon for polyps and cancer. During the test, samples of any growths can be collected (biopsy). And precancerous and cancerous polyps usually can be removed.
CT colonography (virtual colonoscopy).
It uses X-rays to make a detailed picture of the colon to help the doctor look for polyps. If this test finds polyps, you will need to have a colonoscopy.
If a biopsy of polyps found during screening shows only hyperplastic polyps of any size, routine follow-up screening is all that is needed. These polyps don't become cancerous.
Most doctors agree that if you've had one or more adenomatous polyps removed, you probably need regular follow-up colonoscopy exams every few years. This type of polyp is more likely to turn into cancer. But that risk is still very low.
How often you need a colonoscopy may depend on the number and size of the polyps, your age, your health, and other risk factors that you may have for polyps. Talk with your doctor about the follow-up testing schedule that is right for you.