2
Which test?
Choosing a screening test
There is more than one way to screen. The best test is the one you will actually do. Talk with your doctor about your risk and which test suits you.
The main tests
| Test | What it is | How often, if normal |
|---|---|---|
| Colonoscopy | Looks at the whole colon. Polyps are removed during the same exam. | Every 10 years |
| FIT stool test | A stool sample at home, checked for hidden blood. | Every year |
| High-sensitivity guaiac stool test | A stool sample at home, checked for hidden blood. | Every year |
| Stool DNA or RNA test | A stool sample at home, checked for blood and genetic changes. | Every 3 years |
| CT colonography | A CT scan of the colon. Needs a prep. | Every 5 years |
| Flexible sigmoidoscopy | Looks at the lower part of the colon only. | Every 5 years |
| Blood test | Not a preferred test. Misses most precancerous polyps. For people who won't do any of the tests above. | Ask your doctor |
Good to know
- Any abnormal result needs a colonoscopy. If a stool test, scan or blood test finds something, a colonoscopy is the next step. Screening isn't complete until it is done.
- Only a colonoscopy can remove polyps during the test itself.
- Higher risk? If cancer or advanced polyps run in your family, or you have had polyps before, your doctor will usually recommend a colonoscopy.
- Cost: most health plans cover screening with no copay. Ask your plan what it covers, including a follow-up colonoscopy after an abnormal stool test.