Colonoscopy

A colonoscopy is an examination to inspect the inner lining of the large bowel (rectum and colon) using a flexible tube with a camera at its tip. It is inserted via the anus and gently guided to the start of the large bowel (caecum). Carbon dioxide gas is used to inflate the bowel to allow a safe passage of the colonoscope through the bowel. If an abnormality is found a tissue biopsy can be taken through the colonoscope and sent for examination.

If polyps are found, these small growths of the bowel lining can be removed with either cautery (hot biopsy) or a wire loop device (snare). This allows tissue to be retrieved and sent for histological examination. Early detection and removal of polyps protects from developing colorectal cancer.

Preparation is required prior to colonoscopy to empty the bowel of its content. Failure to do this may result in an incomplete or inadequate examination and the need to repeat the procedure. The preparation involves drinking a "bowel prep" solution which has a laxative effect. This should be done at home as you will need to be close to the toilet for the duration of the preparation. During the preparation you are not allowed to eat any solid food. You are allowed clear fluids (apple juice, water, clear soup, etc.) until six hours prior to the procedure.

Only when your bowel motion is the consistency of clear liquid, is your preparation adequate. If your bowel motion is still dirty (brown) you may require further preparation or an enema prior to the colonoscopy. You should fast from six hours prior to the procedure. Take all medication as required with a sip of water during the fasting period.

When you arrive on the day of your colonoscopy you will change into a hospital gown and an intravenous line (drip) will be inserted into your arm. This will allow your doctor to give you intravenous fluid and medication. The procedure is done with sedation or a light anaesthetic.

The procedure takes approximately 30-45 minutes, but longer if polyps are removed or biopsies are taken. After the procedure you will need 1-2 hours to recover from the sedation  or anaesthetic. You should have minimal discomfort. You must not drive or operate  machinery after your procedure and you will need a family member or friend to take you home. You will need to take two days off for the procedure, one for the bowel preparation and the other for recovery from the sedation and procedure.

Colonoscopy is a safe procedure with a low risk of complications. The most significant risk of colonoscopy is a perforation of the bowel. The risk of this is approximately 1 in 1000. If a biopsy or polypectomy is performed the risk of bleeding from this is about 3 in 1000. In addition, although colonoscopy is the best test for detection of cancer there is a small risk of missing a small cancer. The risks and benefits of coloncoscopy should be discussed in detail with your doctor prior to proceeding with the test.

The specific details of your colonoscopy bowel preparation will be discussed and given to you at the time of your consultation.

Reviewed 2017