Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2008;77(7):1003-1004

See related article on colonoscopy surveillance.

What is a colonoscopy?

A colonoscopy (coh-lo-NOS-co-pee) is a test that checks the colon for cancer and other diseases. To do this, your doctor looks into your rectum and colon with a long flexible tube that has a tiny camera at the end of it. If your doctor finds growths, called polyps (PAW-lips), they can be removed. Sometimes these polyps are benign (buh-NINE), which means they are not harmful. But sometimes polyps are cancer or can turn into cancer.

Who should get one?

You should be tested for colon cancer at age 50 if you have no personal or family history of colon cancer. You should begin testing earlier than age 50 if you have a family history of colon cancer. The age you should begin getting tested depends on how many family members have had the disease and their ages when they were diagnosed. Your doctor will help you figure out when you should be tested.

If the results of your colonoscopy are normal, you don't need to have another one for 10 years. You will need to be screened more often if you have polyps removed or if you have had colon cancer. Your doctor will tell you when you should have your next test.

What if I have polyps removed that are not cancer?

You will need to have another colonoscopy if you have any polyps removed. How soon will depend on the type of polyps you had, how big they were, and how many you had.

You should have your next colonoscopy in five to 10 years if:

  • You only had one to two polyps, and

  • Each polyp was smaller than 1 cm (a little less than half an inch), and

  • They are adenomatous (ad-uh-NOM-uh-tus) polyps (a kind of polyp that sometimes turns into colon cancer)

You should have your next colonoscopy in three years if you had:

  • Three to 10 adenomatous polyps, or

  • Any adenomatous polyp larger than 1 cm, or

  • Any polyp that was in the precancer stage and was removed completely

You should have your next colonoscopy in less than three years if you had 10 or more adenomatous polyps at one time.

What if I have polyps removed that are cancer?

If you have polyps removed that were colon cancer, you will need another colonoscopy. How soon depends on if the polyp was removed during the colonoscopy or if you had surgery to remove it.

If you had a type of polyp called a sessile polyp, it may not have been completely removed during the colonoscopy. You will need to have another colonoscopy in two to six months to make sure that the polyp is completely gone.

If you had surgery to remove part or all of your colon, you will need another colonoscopy one year after the surgery.

Where can I get more information?

Your doctor

American Academy of Family Physicians

American Cancer Society

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