Colonoscopy is a form of endoscopic investigation in Singapore that is essentially a ‘camera test’ whereby the internal lining of the colon and rectum are directly visualised using a flexible scope (‘camera’) that is inserted through the anus. Through the scope, a small forceps or a snare can be introduced to allow biopsies and removal of polyps.
A colonoscopy should be considered in patients with suspicious symptoms. These symptoms include a change in bowel movement habits, the sensation of incomplete evacuation of stools, fresh blood in the stools, long-term abdominal pain, and unexplained loss of weight.
Any asymptomatic individual nearing the age of 50 and/or with a family history of colon cancer should also consider undergoing a colonoscopy.
Patients undergoing colonoscopy will be given sedative drugs to minimise discomfort and pain. The sedative drugs also have some amnesia effect to minimise memories of the event.
A colonoscopy is a safe and straightforward procedure. Most patients, regardless of age or underlying medical problems, can undergo the colonoscopy safely.
A CT colonoscopy scan is an alternative to a formal colonoscopy.
The advantage of a CT colonoscopy compared to a formal colonoscopy is the less invasive nature of the CT scan with minimal complications and discomfort. In addition, the CT colonoscopy offers an accuracy level that is only slightly inferior to a formal colonoscopy.
However, the CT colonoscopy still requires bowel preparation like a colonoscopy, and any abnormalities detected on the CT will still require a formal colonoscopy for confirmation and to perform biopsies. In addition, it is advisable to further perform a limited scope (flexible sigmoidoscopy) after a CT colonoscopy to avoid missed lesions in the rectum.
A formal colonoscopy is still the preferred option in most instances to investigate the colon.
The preparation for a colonoscopy is fairly straightforward. Three days prior to the procedure, the patient needs to minimise the intake of fibre in the diet. This is to reduce the bulk of the faeces to allow a clear view of the colon during the scope. Depending on the timing of the colonoscopy, bowel cleansing medications will need to be taken either on the evening before the scope or on the morning of the scope. Bowel cleansing will require the patient to make approximately 5-10 trips to the toilet to empty the colon. Good cleansing is achieved when there is a minimal passage of solid or liquid stools.
It is important to note that a colonoscopy is a very safe procedure. A typical restructured hospital regularly performs more than 50 colonoscopies in a week. The main complications related to colonic perforation and post-procedure bleeding.
The perforation rate ranges from 0.05-0.1% (0.5-1.0 perforation in 1000 colonoscopies) while the bleeding rate ranges from 0.25-1.0%. The higher range of the complication rate usually occurs in colonoscopies where polyp removal is performed. The risks associated with over-sedation is very low and is reversible with medications.
For a colonoscopy performed with a well-cleansed colon and adequate polyp removal, the next scope can be performed in 5 years. However, the endoscopist may recommend for an earlier interval colonoscopy in circumstances such as inadequate colon cleansing, presence of multiple polyps and after removal of large polyps (usually 1cm and larger).