When you need it—and when you don’t

Colonoscopy is the most accurate exam used to detect and prevent cancer of the colon and rectum.  It can find cancer early and save lives. But even a very good exam can be done too often. Here’s when you need it and when you don’t.

What is a colonoscopy?

A colonoscopy uses a flexible, lighted tube to view the colon and rectum. During the exam, doctors can spot and remove small growths, called polyps. They are common and usually harmless. But some polyps, called adenomas, may turn into cancer. Removing these polyps can prevent cancer from developing.

People who are not at high risk need the exam every 10 years.

The exam is very accurate, and colorectal cancer grows slowly.

  • If your exam doesn’t find adenomas or cancer and you don’t have a high risk for colon cancer, you probably won’t need another exam for 10 years.
  • If you have one or two low-risk adenomas removed, you probably won’t need another exam for five years.
  • If you have more serious adenomas, you may need another exam sooner than five years. Very high-risk patients may need the test in just one to three years.

Colonoscopy is safe, but risks can occur.

Colonoscopy can sometimes lead to:

  • Bleeding where a polyp was removed.
  • Reactions to the sedative.
  • Abdominal pain.
  • Small holes in the colon, called perforations.

People with heart and respiratory problems should be evaluated before colonoscopy. For people with these conditions, the procedure should be done in the right facility, with careful monitoring, because there can be serious complications. The benefits of colonoscopy are usually worth the risk. Discuss both the benefits and risks with your doctor.

The exam preparation is worth the effort.

Before your colonoscopy, you have to limit some medicines and foods. For one day, you drink clear liquids only and take laxatives, which may cause discomfort. It’s very important to follow the preparation instructions carefully so the test is as accurate as possible. During the exam, you’ll be given a sedative drug to make you sleep. This means someone will have to help you home. You will also be told not to drive, work, or make important decisions the day of your exam. You can usually return to your routine the next day.

The exam can increase your costs.

The exam is covered as preventive care by Medicare and most health plans. This means there is no co-pay if you have it every 10 years as a screening test. But under Medicare, you may have to pay for related costs, such as anesthesia. And if a polyp is found, you may be responsible for a co-pay or deductible regardless of your insurance. Talk to your insurance provider to find out what’s covered and what’s not. If you don’t have insurance, check if your community has programs to help you get an exam.

When should people get a colonoscopy?

Most people should get screened for colon cancer no later than age 50. If your colonoscopy doesn’t find any signs of cancer, you should have the exam again every 10 years. However, if you’re between 76 and 85, talk to your doctor about how often you should be screened.

Other people might need the exam more often, including those who have:

  • Inflammatory bowel disease.
  • Ulcerative colitis and Crohn’s disease.
  • A history of multiple, large, or high-risk adenomas.
  • A parent, sibling, or child who had colorectal cancer or adenomas.

Other screening tests for colorectal cancer.

If you are not at high risk for colon cancer, talk with your doctor about other exams and tests. Each has pros and cons. Also ask your health plan if it covers:

  • Flexible sigmoidoscopy.
  • Stool tests such as Fecal Immunochemical test, FOBT, and Cologuard.

If one of these finds a problem, you will need a colonoscopy for further evaluation.


This report is for you to use when talking with your healthcare provider. It is not a substitute for medical advice and treatment. Use of this report is at your own risk.

© 2018 ABIM Foundation. Developed in cooperation with the American Gastroenterological Association for Choosing Wisely, a project of the ABIM Foundation.