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We offer Colonoscopy at both our Credit Valley Hospital and Mississauga Hospital locations.

Colonoscopy is a test where a doctor inserts a thin, flexible tube with a camera attached to it into your anus and moves it slowly into your rectum and colon. This allows the doctor to:

  • examine the lining of your colon (large intestine) for abnormalities or disease
  • take pictures of what is seen
  • take a small piece of tissue so that it can be examined under a microscope (this is called a biopsy)

A Colonoscopy can be used to diagnose:

  • cancers and other problems
  • the cause of unexplained changes in bowel habits
  • the cause of pain or bleeding located in the abdominal area

the reason for weight loss, chronic constipation, or diarrhea,


A referral from a doctor is required.​​

Resources for Patients & Their Families

Can I Take My Current Medications If I’m Having a Colonoscopy?
Most medications can be continued as usual, but some medications can interfere with the preparation or the examination. Tell your doctor about medications you're taking, particularly aspirin products, arthritis medications, anticoagulants (blood thinners), insulin or iron products. Also, be sure to mention allergies you have to medications.

How to Prepare for Your Colonoscopy
Your doctor will tell you what you can eat and what laxative to use. In general, preparing for a colonoscopy means taking a special laxative and only consuming clear fluids. Your colon must be completely clean for the procedure to be accurate and complete, so be sure to follow your doctor's instructions carefully.

What to Expect During Your Colonoscopy
You might feel pressure, bloating or cramping during the procedure, but colonoscopy rarely causes much discomfort. Your doctor will likely give you a sedative to help you relax and better tolerate any discomfort.

During the procedure you will lie on your side or back. Your doctor will slowly insert a flexible tube called a colonoscope into your anus. The colonoscope, which is about as thick as a finger, will slowly move through your large intestine to enable your doctor to examine the lining. Your doctor will examine the lining again as he or she slowly withdraws the colonoscope.

The procedure usually takes 10 to 15 minutes, although you should plan on two to three hours for waiting, preparation and recovery.

What If My Colonoscopy Shows Something Abnormal?
If your doctor thinks an area needs further evaluation, he or she might pass an instrument through the colonoscope to obtain a sample of the colon lining to be analyzed. This is called a biopsy. Biopsies are frequently done during colonoscopy and are used to diagnose various conditions.  

If your colonoscopy is being performed to identify sites of bleeding, your doctor might control the bleeding through the colonoscope by injecting medications or by coagulation (sealing off bleeding vessels with heat treatment). Your doctor might also find polyps during colonoscopy, and he or she will most likely remove them during the examination. Taking biopsies and removing polyps does not hurt.

What Are Polyps and Why Are They Removed?
Polyps are abnormal growths in the lining of the colon that are usually harmless (not cancerous). They vary in size from a tiny dot to several centimeters. After a polyp is removed, your doctor will have it analyzed and you will be told what the results are once they are available. Removing polyps does not hurt and is a way to help prevent colon cancer.

How Are Polyps Removed?
There are different ways to remove polyps. Your doctor may use an electrical current, wire loops called snares or biopsy instruments. Removing polyps does not hurt.

What Happens After a Colonoscopy
Your doctor will explain the results of the examination to you, although you will probably have to wait for the results of any biopsies performed.

If you have been given sedatives during the procedure, someone must drive you home and stay with you. Even if you feel alert after the procedure, your judgment and reflexes could be impaired for the rest of the day.

You might have some cramping or bloating because of the air introduced into the colon during the examination. This should disappear quickly when you pass gas.

You should be able to eat after the examination, but your doctor might restrict your diet and activities, especially if you have had polyps removed.

Are There Possible Complications of Colonoscopy?
Colonoscopy and polyp removal are generally safe, but complications are possible.

Bleeding might occur at the site of a biopsy or where a polyp was removed, but it is usually minor. Bleeding can stop on its own or be controlled through the colonoscope; it rarely requires follow-up treatment. Some patients might have a reaction to the sedatives or complications related to their heart or lung disease.

One possible complication is a perforation, or tear, through the bowel wall that could require surgery. Although complications after colonoscopy are uncommon, it is important to recognize early signs of possible complications, such as:

  • severe abdominal pain
  • fever and chills
  • significant rectal bleeding (blood that could fill a half cup measure)
If you notice any of these symptoms, contact your doctor or go to the nearest hospital. Note that bleeding can occur up to 10 days after the procedure.​