A colonoscopy is a procedure to examine the inner lining of the large intestine (colon) and rectum. Colonoscopies are performed with a colonoscope, a long and flexible tube about one metre long. The procedure usually takes around 30 minutes to complete, but it can vary depending on individual circumstances and the addition of necessary interventions.


A colonoscopy is required to check the causes of bowel symptoms or for abnormal growths (polyps or cancers) in the bowel. Your doctor may arrange a colonoscopy to investigate symptoms like abdominal pain, rectal bleeding, sudden weight loss, unexplained fatigue, or changes in bowel habits. Colonoscopies can also be a screening procedure for patients with a strong family history of bowel cancer.

Preoperative Instructions

Prior to the procedure, you will need to follow a specific diet and bowel preparation regimen to empty your colon. This usually involves consuming clear liquids and taking laxatives or enemas to clean out the colon. It is important to follow these instructions carefully to ensure a successful examination.


You will be given a sedative by the anaesthetist. The colonoscope is gently inserted into the rectum and advanced through the colon. The scope has a light and a camera at its tip, which allows the doctor to visualise the colon’s inner lining on a monitor.

Dr Moar may perform interventions during the procedure, such as taking biopsies (small tissue samples) or removing polyps.

Carbon dioxide gas, air or water may be used to expand the colon to get a better view. This may cause some temporary discomfort, such as bloating or cramping, but it usually subsides quickly.

The colonoscope is advanced through the entire colon until it reaches the cecum, which is the beginning of the large intestine, and then into the last part of the small bowel called the Terminal Ileum. Once this is done, the scope is withdrawn slowly to examine for polyps.

Postoperative Instructions

Once the procedure is complete, you will be moved to a recovery area where you will be monitored until the effects of the sedation wear off. It is important to have someone accompany you to drive you home as the sedation can temporarily impair your coordination and judgement.

After the recovery period, Dr Moar will discuss the findings of the colonoscopy with you. If any biopsies were taken or polyps removed, further analysis may be required, and you will be informed of the next steps.


The risks associated with colonoscopy are generally low, and the benefits of early detection and prevention of colorectal cancer outweigh the potential risks in most cases.

General risks include bleeding during or after the procedure, particularly if large polyps were removed or if patients need to be on blood thinning medication, or perforation (a hole) in the colon.

The specific risks can vary depending on individual factors, so it is essential to discuss any concerns or specific risks with your healthcare provider before undergoing the procedure.

Treatment Alternatives

If a colonoscopy is for some reason not possible, there are alternatives including a special CT scan (CT colonography) or a less complete examination of the rectum and distal colon (flexible sigmoidoscopy).