Having Your Colonoscopy

A colonoscopy is a test that examines your colon and rectum (large bowel). It is a soft, flexible tube that is one metre long and the size of your finger. A camera on the end of the tube displays an image on a monitor.

A screening colonoscopy is performed to identify growths in your colon called polyps. These polyps will be removed during the test if it is safe to do so. As some polyps eventually become colon cancer, it is important to remove polyps at an early stage to prevent most cases of colon cancer.

While many people who undergo screening colonoscopy have no symptoms, it is important to know that abdominal pain, rectal bleeding, or a change in bowel habits may suggest an advanced polyp or cancer. The goal of a screening colonoscopy, therefore, is to detect potential problems at an earlier stage - before symptoms may occur.

Colon cancer is very common. A person's lifetime risk of developing colon cancer is about 6%. This risk is higher if you have a personal history of colon polyps or a family history of colon cancer. Unfortunately, many people die from colon cancer. It is the second most common cause of cancer-related death - just behind lung cancer. Among people affected with cancer, only breast and prostate cancer are slightly more common than colon cancer. Therefore, if you are considering a mammogram for breast cancer or PSA test for prostate, you should think about colonoscopy for colon cancer screening.

A colonoscopy is usually a simple test that lasts approximately 15-20 minutes. Please arrive 30 minutes before the test and expect to be leave about 30-60 minutes after the test. An intravenous sedative will be given during the test to make you feel more relaxed. Most people are quite comfortable during the test. Any discomfort during the test is usually mild and transient. If you experience more symptoms, medication will be given if safe to do so.

Since medications are given for the colonoscopy, you will not be able to drive home. Please ensure that someone is available to drive you home or taxi arrangements have been made. The remainder of your day should be quite normal, but you might feel a bit lethargic. You will not be allowed to operate heavy machinery.

You will be asked to take a laxative to cleanse your colon on the day before the test. Certain medications should be discontinued prior to the test. Please have only clear fluids on the day before the test and avoid grains, seeds and roughage for 3 days prior to your test. You will be able to eat normally soon after the test.

A screening colonoscopy is very safe. The gastroenterologist who will be performing the tests is experienced and has special training in doing these procedures. However, as with any test, there are rare risks involved:

  1. The risk of perforation (a tear in your colon) is about 1 in 3000. In the unlikely event that this occurs, you may require surgery. Remember that the risk of having a large polyp or even cancer is greater than the risk of perforation.
  2. Bleeding is infrequent and can often be managed at the time of the colonoscopy. If excessive bleeding occurs within 14 days of the test, you should go to the emergency department.

It is important that you are aware of the different screening modalities that are available. Fecal occult blood stool testing and barium enema x-rays are less invasive tests, but are also less accurate (30-60%) than colonoscopy (94%) for detecting colon cancer. Furthermore, if abnormalities are found on stool testing or barium, a colonoscopy is usually required for further evaluation.

If you have any further questions about colonoscopy, please do not hesitate to ask.


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