What is a colonoscopy?

A procedure to examine the inside lining of the large intestine (colon), which is done with an instrument called a colonoscope. This is a thin, flexible tube, which has a tiny camera and light on the end. You will need to take bowel preparation to clean out the colon, so that good views of the lining are obtained. Sedation or an anaesthetic is given for the procedure.

What are the benefits?

Colonoscopy is the most complete way to examine the colon and detect bowel cancer. Polyps (pre-cancerous growths) growing on the inside lining of the colon may be found. These can be removed by applying a heated wire loop to the base of the polyp. One third of patients will have at least a single small polyp (less than 1cm in diameter). Biopsies (tissue samples) of the inside lining may be taken, to aid in the diagnosis of inflammatory conditions of the bowel.

What are the risks?

Complications are rare.

• An abnormality may be missed. This happens about 1/20 times, but usually only tiny polyps are missed. This is more likely when the bowel is not adequately cleaned.
• Major bleeding occurs in about 1/2000 procedures. This is usually after a polyp is removed (1/100 bleed after removal of a polyp). Bleeding is usually minor, but major bleeding may require blood transfusion, admission to hospital and a repeat procedure to treat the bleeding point. Extremely rarely a special x-ray procedure or surgery may be needed.
• A small hole or perforation in the lining can occur (1/2000 procedures). The risk is highest amongst those with inflammatory disease of the bowel where there is narrowing and severe inflammation, or in the very frail and unwell. Those having a large polyp removed are at higher risk (1/200). Usually surgery is performed to repair the hole.
• Very frail and elderly patients may rarely get pneumonia from the stomach juices getting into the lung during the sedation.
• Reactions to the sedation are uncommon.
• The colonoscopy may not be completed if the bowel preparation is inadequate or where unusual anatomy makes passing the colonoscope too dangerous (1/100).

What happens after the colonoscopy?

Usually you will eat straight away. Most outpatients will be discharged on the same day. You will need someone to drive you, as you may be sleepy from the sedative you received. Avoid driving, operating machinery or drinking alcohol for 24 hours.

When you get home, if you notice heavy bleeding from your rectum OR red OR black stools, OR vomiting, OR severe abdominal pain, OR weakness OR dizziness, OR fever over 37.5 degrees, seek medical advice. These problems are not common, but if you become unwell, you will need to call the hospital to speak to a doctor or present to the Emergency Department.

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