• COVID-19 Update

    In order to reduce the risk of spreading the COVID-19 infection and in accord with an Ontario Public Health order to stop elective procedures in the province, Dr. Reimer has cancelled all procedures until public health officials advise that it is appropriate to resume. We regret the inconvenience. For more details, please see this statement from the Ministry of Health about ramping down elective procedures. In case of urgent need, please ask your referring physician to send you to an in-hospital provider where certain non-elective procedures are still being performed if prerequisite conditions are met. Updated: March 22, 2020.

What to Expect

Having a Colonoscopy

We'll do our best to make it easy.

Do you Need a Colonoscopy?

In Canada, most people should begin their screening against colon cancer at age 50. In the USA, the American Cancer Society recommends starting at age 45. See their guidelines for who should start when. Some people are at higher risk and should begin sooner. These guidelines give several screening options, including colonoscopy.

Many colonoscopies are performed for symptom investigation. See your doctor if you have symptoms such as rectal bleeding, a change in bowel habits or abdominal pain. These symptoms could lead you to needing a colonoscopy.

The Experience

Most people say the hardest part is the bowel preparation. With sedation, most people find that the test is not uncomfortable and many are asleep during the procedure and do not remember it. Others are fully awake and remember everything, and are fascinated to see a part of their body they have never seen before. For a few people, it can be painful. These people often have advanced irritable bowel syndrome. In that case, one can always stop the colonoscopy part-way.

The Risks and Benefits

Colonoscopy is the best test to prevent colon cancer, but it is also the most invasive of the screening options. The risks of colonoscopy include:

  • the bowel preparation. Rare electrolyte abnormalities are possible. If you have renal disease, be sure to tell your physician.
  • cardiac and respiratory risks from the sedation.
  • a small risk of bleeding and infection.
  • the risk of bowel perforation (making a hole in the bowel with the colonoscope) is about 1 in 3,000 for a diagnostic procedure, but if polyps need to be removed, the risk increases. If a perforation occurs, surgery is sometimes needed. It is possible to reach the end of the large bowel 95% of the time. If the colonoscopy cannot be completed then a back-up test such as a virtual colonoscopy may be ordered to assess the remaining colon. There is a small rate of not seeing colonic lesions. People who have a history of abdominal surgery or bowel obstruction undergo a small risk that colonoscopy may cause a bowel obstruction.

The primary benefit of colonoscopy is that it helps keep you safe from colon cancer, and if you have symptoms, it may give you some answers as to what's going on.

The Procedure

You will need to take a bowel preparation starting the day before the colonoscopy. When you arrive at the clinic you will be registered. A nurse will place an intravenous catheter. You will then enter the procedure room where you will meet the physician. Most people fall asleep with the sedative medications and wake up once the test is completed. If you wish to watch the procedure or to have less or no sedation, please discuss this with your physician. After, you will rest in the recovery room for about an hour. We will give you a written summary of the results to take home with you. A report will be faxed to your referring physician (yes, you read that correctly, the illustrious fax machine is still deeply entrenched in health care!).

You cannot drive a motor vehicle or operate machinery or engage in other tasks that require attention for 24 hours after having sedation.


If you wish to discuss the results of your procedure or any biopsies taken during your colonoscopy, you may book an appointment with The Reimer Clinic. You may also discuss the findings with your family physician. Biopsy results will be available about three weeks after your procedure. Please contact us if you wish to have a copy.

We know there are many clinics and hospitals that provide colonoscopy care. Thanks for choosing us!

Colonoscopes prepared for use