Health Corner

What is colorectal cancer?
According to the 2009 statistics from the Hospital Authority’s Hong Kong Cancer Registry, colorectal cancer ranks second among all cancers in Hong Kong in terms of incidence and mortality. Colorectal cancer primarily develops from intestinal polyps through a process that can be symptomless and takes about 10 years. Early detection and removal of polyps can reduce the chance of progression to cancer. Therefore, it is recommended that people aged 50 or above undergo regular colonoscopy screenings. Those with a family history of colorectal cancer or other high-risk factors should consider earlier screening (from age 40 or 10 years before the relative’s diagnosis) and more frequent examinations for prevention.

What is a colonoscopy?
Colonoscopy is an endoscopic examination of the lower digestive tract using a soft tube about 1.3 cm in diameter with a camera at the tip. It examines areas including the terminal ileum, cecum, colon, rectum, and anus to detect tumors, polyps, inflammation, or bleeding. If needed, doctors may take tissue samples for biopsy or remove polyps during the procedure.

Since most colorectal tumors develop from polyps, early detection and polyp removal help reduce disease incidence. As such, colonoscopy is an effective colorectal cancer prevention method.

Who should get a colonoscopy?

• People aged 50 and older

• Those with a family history of colorectal cancer

• Individuals with a history of colorectal polyps

• People with chronic diarrhea

• Those with blood in the stool

• People with changes in bowel habits (such as constipation or diarrhea)

What preparation is needed before a colonoscopy?

• The bowel must be thoroughly cleaned for clear observation, so patients take prescribed laxatives before the procedure.

• Patients with diabetes, hypertension, heart disease, kidney disease, those on low-salt diets, taking medications, or pregnant or breastfeeding women should inform healthcare providers and follow guidance carefully. Details of all medications, especially those affecting blood clotting or allergies, should be provided.

• Avoid high-fiber foods 3 days before the exam.

• Only consume liquids 1 day before the exam.

• Drink clear, fiber-free drinks up to 4 hours before the exam.

• Arrive 30 minutes early.

• Bring a companion—do not drive yourself home.

• For same-day gastroscopy, fast from solid and liquid foods for 6 hours beforehand.

• Healthcare staff will explain the procedure and risks, and patients must sign a consent form.

What is the procedure like?

• Remove metal objects, jewelry, or dentures.

• Lie on your side with knees bent.

• Sedation is given through an IV; the procedure usually takes 30–60 minutes depending on complexity.

• Afterward, rest in the recovery room until sedation wears off.

• Due to sedation, it’s safest to have a companion for the trip home.

• Avoid eating for 1–2 hours post-procedure.

• Some abdominal bloating or mild discomfort may occur.

• If bleeding, severe pain, or other serious symptoms occur, seek emergency care immediately.

This content is for educational purposes only. Please consult your doctor for personalized medical advice.