Colonoscopy

Written by A/Prof Viraj Kariyawasam, Gastroenterologist

1. What is a Colonoscopy?

A colonoscopy is a procedure used to examine the lining of the large bowel (colon) and rectum. It is performed using a long, flexible tube with a camera on the end, allowing direct visual assessment of the bowel.

Colonoscopy is commonly used to investigate bowel symptoms and is the most accurate test for detecting bowel polyps, inflammation, and bowel cancer. It also allows treatment, such as removal of polyps, during the same procedure. It is also the gold standard test for bowel cancer screening and surveillance, particularly for people over the age of 45, those with a family history of bowel cancer, or patients with inflammatory bowel disease.

2. What Happens During a Colonoscopy?

Before a colonoscopy, the bowel must be completely cleaned using a special preparation prescribed by your doctor. This is a crucial step to ensure the bowel lining can be properly assessed. Adequate bowel preparation is essential, as poor preparation may result in missed lesions or the need to repeat the procedure.

On the day of the procedure, sedation is usually given through a vein to keep you comfortable. The colonoscope is gently passed through the back passage and guided around the colon. Air or carbon dioxide is used to inflate the bowel for better visibility. If polyps or abnormal areas are found, they can be removed or biopsied at the same time. The procedure usually takes 20 to 45 minutes.

3. Recovering From a Colonoscopy

After the procedure, you will be monitored until the sedation wears off. You may feel bloated or pass wind due to the air used during the examination. If polyps are removed, your doctor will advise on activity restrictions and follow-up intervals. Surveillance timing depends on findings and individual risk factors.

Because of sedation, you must not drive, operate machinery, or make important decisions for the rest of the day. Most people return to normal activities the following day. Your doctor will discuss the findings with you and advise when results of biopsies will be available.

4. Risks of Colonoscopy

Colonoscopy is a very safe procedure, and serious complications are uncommon. Potential risks include bleeding, particularly if a polyp is removed, reaction to sedation, or very rarely a tear in the bowel wall.

You should seek urgent medical attention if you develop severe abdominal pain, persistent bleeding, fever, or dizziness after the procedure.