A colonoscopy is a crucial 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.

Why Is It Done?

Your doctor may recommend a colonoscopy to:

  • Investigate intestinal signs and symptoms: It 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 45 or older and at average risk of colon cancer, your doctor may recommend a colonoscopy every 10 years or sometimes sooner. If you have other risk factors, your doctor may recommend screening sooner. Colonoscopy is considered the most effective screening test for colon cancer.
  • Look for more polyps: If you have had polyps before, your doctor may recommend a follow-up colonoscopy to look for and remove any new polyps. This is done to reduce your risk of colon cancer.

How to 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.
  • Take a laxative: Your doctor will usually recommend taking a laxative, either in pill form or liquid form.
  • Adjust your medications: Remind your doctor of your medications at least a week before the exam.

What to Expect

During the procedure, you'll likely be given a mild sedative, sometimes combined with pain medication, to minimize any discomfort.

The doctor inserts the colonoscope into your rectum. The scope is long enough to reach the entire length of your colon. It contains a light and a tube that allows the doctor to pump air or carbon dioxide into your colon. The air or carbon dioxide inflates the colon, which provides a better view of the lining of the colon.

When the scope is moved or air is introduced, you may feel abdominal cramping or the urge to have a bowel movement. The exam typically takes about 30 to 60 minutes.

After the Procedure

After the exam, it takes about an hour to begin to recover from the sedative. You'll need someone to take you home because it can take up to a day for the full effects of the sedative to wear off. Don't drive or make important decisions or go back to work for the rest of the day.

Colonoscopy is a powerful preventive tool. Don't delay your screening; it could save your life.