What is Colonoscopy?

A Colonoscopy is a procedure to look inside the colon and examine its lining. Gastroenterologists are the colonoscopy specialists that perform this procedure. They have received special training to carry out this procedure and to diagnose colonic diseases. The colonoscope is a flexible tube that is long and thin, about the width of a finger. It is gently inserted through the anus and to visualise the entire colon and the last part of the small intestine (ileum) . The tube has a camera and light attached on the end, to allow the live viewing and visual images of the colon, which will be displayed on the screen. The examination is done under moderate sedation, which means the patient will not be conscious during the procedure.


The gastroenterologist passes the colonoscope through the anus into the colon until the start of the colon (caecum). The scope is then passed into the terminal ileum (the last part of the small intestine). The colon is washed clean and examined in detail. A colonoscopy usually takes 20 to 30 minutes, of which at least 10 minutes would be spent inspecting the colon during the scope removal. 


Procedures that are performed via instruments that are passed through the scope are indicated below:

  • Biopsies: Tissue samples can be obtained in a systematic manner or guided by enhanced imaging systems
  • Polypectomy: Precancerous growths can be removed with the use of snares.
  • Hemostasis: Various devices such as heater probes, clips and sprays can be used to stop internal bleeding 
  • Foreign body removal
  • Dilatation and Stenting: Blockages may be bypassed

Colonoscopy is used to investigate certain digestive symptoms, before diagnosing colon diseases.  These symptoms include:

  • Change of bowel habit, persistent diarrhoea or constipation
  • Blood or mucus in stool
  • Unexplained weight loss
  • Abdominal pain, discomfort or bloating
  • Iron deficiency anaemia

Colonoscopy is also the primary tool for colon cancer prevention. Colonoscopy is proven to decrease the risk of colon cancer in anyone above 45 years, or who has a family history of colon cancer or other risk factors. Colonoscopy prevents cancer by detecting precancerous growths called polyps. These can be removed in the procedure to prevent them from growing and becoming cancerous.


You should fast for at least 6 hours prior to your colonoscopy. You may drink only clear fluids up to 2 hours before the colonoscopy treatment procedure.

You will be given medication to clear your bowels to prepare for the procedure. This is known as bowel preparation. It is important to adhere to the instructions for bowel preparation.

In general, most medications can be continued before the colonoscopy with the exception of diabetic medications and blood thinners. Diabetic medications should be omitted during the fasting. You should check with your colonoscopy doctor if your blood thinner needs to be ceased prior to the procedure.

You will also be given medication that will make you sleepy. Therefore, you must not drive, work or make any important decision after the procedure. A Medical Certificate will be issued, and you should rest at home for the rest of the day.


A nurse will conduct pre-procedure checks, and bring you into the procedure room where an intravenous line will be inserted.


You will be positioned to lie on your left. Sedation will then be administered. After you have fallen asleep, the procedure will begin. It is likely that you will not remember any parts of the procedure. You will be breathing on your own and monitored closely during the procedure. Once the procedure has been completed, you will wake up gradually.


You will be cared for in a recovery area or room. You will be monitored until you have regained consciousness from the anaesthesia. The nurses will provide food and drink after post-procedure assessments. You should arrange for a family member to take discharge instructions and take you home. You should only resume going to work and/or drive the following day. It is common to have mild abdominal discomfort or bloating after a colonoscopy. This usually goes away after 24 hours.

Your colonoscopy doctor will fix an appointment to explain the colonoscopy treatment procedure and findings, including the results of any biopsies taken. He will then discuss the appropriate management plan.


Colonoscopy is a very safe examination. Complications are rare and overall occur in 0.1% of colonoscopies. These are often due to disease factors. Such complications include tearing of the colon wall, bleeding and anaesthetic adverse reactions. Unfortunately, emergency surgery or urgent hospitalisation may be required. The risk may be higher in complex cases or those involving interventions. Your doctor will advise you on the complications, precautions, and on what to do should these events occur.


Quality of colonoscopy is imperative and depends heavily on the specialist. A good specialist can complete a colonoscopy almost all the time, with good photo-documentation of landmarks, and comprehensive report writing using international nomenclature. In cancer screening, the specialist should be able to detect precancerous polyps in at least 25% of patients, and to remove these polyps according to the latest standards recommended for each polyp type and size. 

Hence, it is important to have good bowel preparation. Otherwise, the colonoscopy may fail to provide an accurate and complete diagnosis. A good quality control program will help assure patients that their colonoscopy meets the required international standards.


A colonoscopy is a hospital procedure and is covered under most hospitalisation plans. It is also Medisave deductible. Many companies’ health benefits and private health insurances cover colonoscopy treatment costs in Singapore, which may extend to the private sector. The Ministry of Health provides fee benchmarks and publishes the average fees in each hospital. Before any endoscopic procedure, a detailed financial counselling is done to help patients understand the cost breakdown. Patients should check with their insurance provider and do their own research before seeing a colonoscopy specialist.