A colonoscopy (koe-lun-OS-kuh-pee) is an exam used to look for changes — such as swollen, irritated tissues, polyps or cancer — in the large intestine (colon) and rectum.

During a colonoscopy, a long, flexible tube (colonoscope) is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the inside of the entire colon.

If necessary, polyps or other types of abnormal tissue can be removed through the scope during a colonoscopy. Tissue samples (biopsies) can be taken during a colonoscopy as well.

Why it’s done

Your doctor may recommend a colonoscopy to:

• • Investigate intestinal signs and symptoms. A colonoscopy can help your doctor explore possible causes of abdominal pain, rectal bleeding, chronic diarrhea and other intestinal problems.
• • Screen for colon cancer. If you’re age 45 or older and at average risk of colon cancer — you have no colon cancer risk factors other than age — your doctor may recommend a colonoscopy every 10 years. If you have other risk factors, your doctor may recommend a screen sooner. Colonoscopy is one of a few options for colon cancer screening. Talk with your doctor about the best options for you.
• • Look for more polyps. If you have had polyps before, your doctor may recommend a follow-up colonoscopy to look for and remove any additional polyps. This is done to reduce your risk of colon cancer.
• • Treat an issue. Sometimes, a colonoscopy may be done for treatment purposes, such as placing a stent or removing an object in your colon.

Risks

A colonoscopy poses few risks. Rarely, complications of a colonoscopy may include:

• • A reaction to the sedative used during the exam .
• • Bleeding from the site where a tissue sample (biopsy) was taken or a polyp or other abnormal tissue was removed
• • A tear in the colon or rectum wall (perforation)

After discussing the risks of colonoscopy with you, your doctor will ask you to sign a consent form giving permission for the procedure.