Colonoscopy is an endoscopic examination commonly performed to look at the inner lining (mucosa) of the large bowel (colon) and the portion of small bowel leading to it.

Colonoscopy is the most effective way to detect polyps in the large bowel and in most instances can remove the detected polyps in the same examination session. Certain types of polyps are known to be precursors of cancer, and their removal is now proven to be an effective cancer-prevention strategy.

All endoscopes used at the Centre is of High-Definition resolution and equipped with Narrow-Band Imaging (NBI), to facilitate detection and diagnosis of polyps.

How should you prepare for Colonoscopy?

To help the physician obtain a clear view to the inner lining of the gut, a change in diet and bowel cleansing are necessary before the examination. Low residue diet should be started three days before the examination. On the day before the examination, only fluid diet should be consumed.

Bowel cleansing with a laxative prescribed to you should be taken starting the day before the examination day.

Certain medications might affect the examination. For example, iron supplements form black stains in the large bowel that cannot be easily washed away with bowel cleansing agents, and should be avoided for at least one week before the examination. Blood-thinners such as aspirin, clopidogrel (Plavix) and warfarin might cause bleeding after polyp removal. Therefore it is very important that you inform our staff of all drugs and supplements taken by you.

What will happen during and after Colonoscopy?

You will receive medications to put you to sleep and ease any discomfort during the examination. The physician will then put a flexible endoscope into your large bowel. The whole procedure usually lasts 15 to 30 minutes.

After the procedure you will wake up, but still feel sleepy. Please take rest in the recovery area until you have regained full strength. You should not drive, operate heavy machinery, perform hazardous activities or sign legal documents on the day of examination as the drug effect takes time to completely wear off.

If you develop bleeding from the anus or severe abdominal pain in the ensuing days, please seek medical attention.

What if there is an abnormality on Colonoscopy?

The common finding during colonoscopic examination include polyp, inflammation, hemorrhoid, or cancer of the large bowel.

The term “polyp” simply describes an outgrowth from the colonic lining. Polyps are divided into various types according to their causes and behaviors. Adenomatous polyps are the ones with potential to change into cancer, and are the main target for cancer screening and prevention. However, it is not always possible to tell adenomatous polyps from non-adenomatous ones based on endoscopic examination alone. The physician will usually remove all polyps detected and submit them for microscopic examination, which would confirm the polyp types. In general, polyps should be followed up with another colonoscopy several years later; your physician will tell you the exact time frame based on the number and characteristics of the polyps found.

If a hemorrhoid is detected, it can be tackled with a special apparatus during the procedure, please discuss with your physician before the procedure if you would like to receive this treatment.

If other findings are detected, your physician may take biopsy and submit them for microscopic examination.

Type of PolypsRecommendation
HyperplasticRepeat examination in 7 to 10 years if asymptomatic
(Except those with family history)
Adenomatous * 
  • All low grade dysplasia
  • All less than 5mm in size
  • Repeat examination in 5 years if asymptomatic
  • 3 to 10 polyps
  • Polyp size more than 1cm
  • Moderate / High grade dysplasia
  • "Villour" subtype
  • Repeat examination 3 years later if asymptomatic
  • More than 10 polyps
  • Repeat examination within 3 years if asymptomatic

    *First degree relatives of those having adenomatous polyps should consider early screening