A colonoscopy is an exam performed in order to view the inside of the colon (large intestine) and rectum, using a tool called a colonoscope. The colonoscope has a small camera attached to a flexible tube that can extend the length of the colon.

What should I expect to happen when a colonoscopy is performed? A colonoscopy is most often performed in a procedure room at your doctor’s office. It can also be performed in the outpatient department of a hospital or medical center.

• You will be asked to remove your street clothes and wear a hospital gown for the procedure.
• Generally a patient receives IV (administered through a vein) medicine to help relax. The medication allows you to feel no pain. You may be awake during the test and may even be able to speak. However, you will likely remember nothing.
• You will lie on your left side with your knees drawn towards your chest.
• The scope is gently inserted through the anus. It is carefully moved into the lowest part of the large intestine. The scope is slowly advanced as far as the lowest part of the small intestine.
• Air is inserted through the scope to provide a better view. Suction may be used to remove fluid or stool.
• The doctor gets a better view as the scope is moved back out. So, a more careful exam is done while the scope is being pulled back.
• Tissue samples (biopsy) or  polyps may be removed using tiny tools inserted through the scope. Photos may be taken using the camera at the end of the scope. If needed, procedures, such as laser therapy, are also done.

Why is a colonoscopy performed? A colonoscopy may be performed for the following reasons:

• As a screening for colorectal cancer. All adults beginning at age 45 or older are at average risk for colon cancer should be screened.
• Due to abdominal pain, changes in bowel movements, or weight loss
• Due to abnormal changes (polyps) found on sigmoidoscopy or x-ray tests (virtual colonoscopy, CT scan, or barium enema)
• Due to Anemia due to low iron (usually when no other cause has been found)
• Due to blood in the stool, or black, tarry stools
• As a follow-up of a past finding, such as polyps or colon cancer
• Due to inflammatory bowel disease (ulcerative colitis and Crohn disease)

If you have additional questions, always remember that your doctor is a partner in your health care. He or she can discuss any questions or concerns that you may have.