Colonoscopy is the examination of your colon (large bowel) using a colonoscope (long, flexible tube with a camera on the end). The colonoscope is passed into your rectum (bottom) and then moved slowly along the entire colon, while images from the camera are displayed on a television monitor. The procedure takes from 10 minutes to an hour. Sometimes a small tissue sample (biopsy) will need to be taken during the procedure for later examination at a laboratory.

A colonoscopy may help diagnose conditions such as polyps (small growths of tissue projecting into the bowel), tumours, ulcerative colitis (inflammation of the colon) and diverticulitis (inflammation of sacs that form on the walls of the colon).

Colonoscopy may also be used to remove polyps in the colon.

Risks of a colonoscopy are rare but include: bleeding if a biopsy is performed; allergic reaction to the sedative; perforation (tearing) of the bowel wall.

What to expect

It is important that the bowel is completely empty before the procedure takes place. This means that you will only be able to have liquids on the day before, and will probably have to take some oral laxative medication (to make you go to the toilet more).

When you are ready for the procedure, you will be given medication (a sedative) to make you go into a light sleep. This will be given by an injection into a vein in your arm or hand.

The colonoscopy will usually take 15 – 30 minutes, but you will probably sleep for another 30 minutes. Because you have been sedated (given medication to make you sleep) it is important that you arrange for someone else to drive you home.

Some patients may experience discomfort after the procedure, due to air remaining in the colon.