Colonoscopy

Overview

A colonoscopy (koe-lun-OS-kuh-pee) is an exam used to detect changes or abnormalities 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 constipation, chronic diarrhea and other intestinal problems.
• Screen for colon cancer.
  If you’re age 50 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 or sometimes sooner to screen for colon cancer. Colonoscopy is one option for colon cancer screening. Talk with your doctor about your options.
• 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.

Risks

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

• Adverse 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 authorizing the procedure.

How you prepare

Before a colonoscopy, you’ll need to clean out (empty) your colon. Any residue in your colon may obscure the view of your colon and rectum during the exam.

To empty your colon, your doctor may ask you to:

• Follow a special diet the day before the exam.
  Typically, you won’t be able to eat solid food the day before the exam. Drinks may be limited to clear liquids — plain water, tea and coffee without milk or cream, broth, and carbonated beverages. Avoid red liquids, which can be confused with blood during the colonoscopy. You may not be able to eat or drink anything after midnight the night before the exam.
• Take a laxative.
  Your doctor will usually recommend taking a laxative, in either pill form or liquid form. You may be instructed to take the laxative the night before your colonoscopy, or you may be asked to use the laxative both the night before and the morning of the procedure.
• Use an enema kit.
  In some cases, you may need to use an over-the-counter enema kit — either the night before the exam or a few hours before the exam — to empty your colon. This is generally only effective in emptying the lower colon and is usually not recommended as a primary way of emptying your colon.
• Adjust your medications.
  Remind your doctor of your medications at least a week before the exam — especially if you have diabetes, high blood pressure or heart problems or if you take medications or supplements that contain iron.