Gastroscopy & Colonoscopy

Why screening matters in Singapore

Colorectal cancer is the second most common cancer in Singapore, in both men and women. The Singapore Cancer Registry’s 2023 annual report records it as 15.8% of all cancers in males and 12.6% in females between 2019 and 2023, and one of the leading causes of cancer death. The critical fact for patients: most colorectal cancers develop from polyps — small growths that are harmless when found early and removed, and dangerous when left for years. Early-stage colorectal cancer very often has no symptoms at all, which is why screening — rather than waiting for symptoms — is how polyps are found and removed before they can become cancers.

What the procedures involve

A colonoscopy examines the entire large intestine using a flexible camera passed through the rectum. A gastroscopy examines the oesophagus, stomach and first part of the small intestine, passed through the mouth. Both are performed under sedation, both take roughly 15–30 minutes, and both are day procedures at Ministry of Health–accredited endoscopy centres.

They are diagnostic and therapeutic at once: small and moderately sized polyps found during a colonoscopy are removed in the same sitting, suspicious areas are biopsied, and certain causes of gastrointestinal bleeding can be treated endoscopically on the spot. Very large or complex polyps sometimes need a planned second procedure — a decision I explain at the time.

Who should be screened

• Adults aged 50 and above — routine screening, even without symptoms
• Those with a family history of colorectal cancer — screening should begin 10 years before the age at which the family member was diagnosed, and may need to be more frequent
• Anyone with symptoms or positive screening tests, including: rectal bleeding, a persistent change in bowel habit, unexplained weight loss, mucus in the stool, abdominal bloating or pain lasting more than two weeks, iron deficiency anaemia, a positive FIT/FOBT stool test, or inflammatory bowel disease. Raised tumour markers found on other tests are an indication for diagnostic colonoscopy rather than a screening tool in themselves

Repeat intervals depend on what is found — typically every 3 to 10 years, so most people need only two or three colonoscopies in a lifetime.

What to expect

Before: bowel preparation to empty the colon (newer preparations are far more manageable than their reputation), fasting for at least six hours, and a medication review — blood thinners in particular may need adjusting.

During: sedation is given for comfort — most patients sleep through the procedure. Polyps found are removed there and then where safe to do so.

After: you wake within 15–30 minutes and are discharged shortly after. Arrange for someone to take you home, and avoid driving or important decisions for the rest of the day. Mild bloating that settles with walking is common; persistent pain, bleeding or fever warrant immediate review. I explain the findings the same day, with biopsy results at follow-up.

When to see a doctor promptly

Fresh rectal bleeding, black stools, persistent vomiting, difficulty swallowing, or unintended weight loss should be assessed early rather than watched — these are the symptoms where an endoscopy earns its keep.