Friday, May 2, 2008


Colonoscopy refers to an examination whereby the entire inner lining of the large intestines is visualized using a flexible instrument inserted through the anus. The procedure is done under light sedation and is therefore performed without discomfort. As the large intestines is filled with feces, a 2-3 hour period of colon cleansing is performed before the examination in order to allow for unobstructed visualisation. The procedure is done as an outpatient and usually takes only about 20-30minutes to complete. Results are available immediately.

This is now the procedure of choice for the detection and diagnosis of diseases of the large intestines, ranging from cancer to benign growths ( eg polyps ) to unusual infections and inflammatory conditions ( eg Crohn’s Disease , ulcerative colitis ). If abnormalities are detected, tissue can be obtained for detailed microscopic examination. If growths are detected ( eg polyps ) , they can also be removed at the same time through the examining instrument, without the need for “open” operation.

Colonoscopy is a very powerful tool for large intestinal cancer screening and prevention. This now the most common cancer in Singapore. A normal examination gives re-assurance that the risk of developing large intestinal cancer should be minimal for the next 5-8 years. If polyps ( pre-cancer tumors ) are found, they can also be removed to prevent their transformation to cancer in the future. Generally, the risk of developing large intestinal cancer increases after the age of 45 years and this is the age when screening may be considered. Individuals with family members who have developed large intestinal cancer are at increased risk and should be screened earlier and regularly.

Other situations where colonoscopy is useful include

Evaluation of symptoms of possible large intestinal disease

- Abdominal pain
- Abdominal lump
- Lump or pain at the anus
- Vomiting or passage of blood in stools
- Prolonged diarrhoea with or without blood
- Pain on passing motion
- Feeling of incomplete bowel evacuation
- Constipation
- Change in bowel habits and stool characteristics ( eg fragmentation, small caliber stools )
- Unexplained weight loss
- Unexplained anaemia
- Unexplained abdominal swelling

Consultations for evaluation of abnormal blood tests and X-rays

- Elevated cancer markers ( eg CEA, CA19-9 )

- Low hemoglobin of unknown cause
- Positive stool blood test
- Abnormal Xrays eg Barium enemas, computer scans

Dr Cheong Wei Kuen
MBBS (Singapore), MRCP (UK), M Med (Int Med), FAMS (Gastroenterology)
Consultant Physician & Gastroenterologist
Mount Elizabeth Medical Centre
WK Cheong Gastrointestinal & Liver Specialists Pte Ltd