What is a colonoscopy?

Colonoscopy is a procedure whereby a colonoscope (a flexible tube with a camera at the distal end) is passed through the rectum and colon to the terminal ileum. It allows the Gastroenterologist to carefully examine these areas as well as perform biopsies or remove polyps. This procedure may be performed to investigate symptoms such as rectal bleeding, anaemia, diarrhoea, constipation, abdominal pain, weight loss or a family history of bowel cancer.

How do I prepare for a colonoscopy?

For a successful colonoscopy, it is important that the colon is clean of all faecal material. This is achieved by taking a bowel preparation, modifying your diet, and increasing your fluid intake. The bowel preparation will flush out the colon resulting in diarrhoea, which should become clear when the colon is clean. Your Gastroenterologist will provide you with specific instructions for the bowel preparation, which can be purchased from your local pharmacist.  If the colon is not adequately clean, important abnormalities such as polyps could be missed, or you may have to repeat the procedure. 

An empty stomach is essential for a safe procedure, so you should have nothing to eat for at least six hours beforehand. You may drink ‘clear fluids’ only (i.e. water, clear fruit juice without pulp, cordial, black tea/coffee WITHOUT milk, sports drinks, soft drinks) up until two hours prior to your procedure. After that you must remain strictly nil by mouth (apart from a sip of water with any important regular medicines – but do not take any diabetic medications). Patients taking diabetic or blood thinning medications should inform their Gastroenterologist as they may require specific instructions.

How is a colonoscopy performed?

Deep sedation is administered by an anaesthetist prior to your procedure so that you are comfortable.  Once sedated and lying comfortably on your left side, a colonoscope is passed through the rectum and colon to the terminal ileum. A camera at the end of the scope transmits a video image to a monitor, allowing the Gastroenterologist to carefully examine the lining of your colon and perform interventions if necessary. If polyps (precancerous growths on the colon wall) are found during the procedure they will be removed using a small snare as this is an effective way to prevent colorectal cancer. Biopsies of the colon may also be taken for examination. The procedure takes approximately 20-30 minutes to complete.

What happens after a colonoscopy?

Following the procedure, you will remain in the recovery area for an hour or so until the sedation medication wears off. Your Gastroenterologist will briefly inform you of the findings of your procedure and if necessary, a follow-up appointment may be made to discuss the results in more detail. Because of the sedation medication given during the procedure, it is very important that you do not drive a car, travel on public transport or catch a taxi/uber alone, operate machinery, sign legal documents or drink alcohol within the first 24 hours after the procedure. After 24 hours you can return to work and resume normal activities. It is mandatory that a responsible adult accompanies you home after the procedure and stays with you overnight. 

What are the risks or side-effects?

Although complications can occur with any procedure, they are very uncommon after diagnostic colonoscopy. Common side-effects may include bloating or abdominal discomfort which should resolve within an hour or so. Occasionally you may pass a small amount of blood which does not require treatment. The risks of significant bleeding, perforation, splenic injury, or aspiration (chest infection) following diagnostic colonoscopy are estimated at 0.1%. Surgery may be required to repair a perforation. Other potential risks including but not limited to cardiopulmonary events and infection are rare. The rate of complications may be higher for patients undergoing therapeutic procedures. Whilst colonoscopy is an accurate way to examine the colon, it is possible that small but significant lesions may be missed. Like all medical procedures, there is a remote chance that a significant complication can result in death, however this is exceedingly rare (3 in 100,000 cases) following diagnostic colonoscopy.