Colonoscopy is an investigatory procedure which allows the doctor to look at the inner lining of the large bowel (colon) by using a long flexible tube (the size of your index finger) with a light source and a tiny video camera at the end. The tube is passed carefully through the anus and the doctor looks inside the colon for pathologies such as inflammation, bleeding, polyps or tumours. Biopsies (small pieces of tissue) may be taken and polyps can be removed with tiny forceps during colonoscopy. Taking biopsies is painless and safe.
Who should have colonoscopy?
The procedure is indicated for:
- Per rectal bleeding
- Change of bowel habit
- Unexplained abdominal pain
- Suspected colonic polyps
- Suspected colonic cancer
- Colorectal cancer screening
Colorectal cancer screening – Do I need colonoscopy?
Colorectal cancer is the second most common cancer in Hong Kong after lung cancer. Because it starts as a polyp that transforms into cancer in 10-15 years, colorectal cancer is preventable when polyps are found and removed at early stages. A Hong Kong colorectal cancer screening study found that 1 in 8 asymptomatic adults older than 50 had adenomatous polyps in their colons. Their polyps may turn into cancer if not removed.
As most polyps are asymptomatic, those above the age of 45 should consider undergoing colonoscopy regularly to screen for colorectal cancer as a preventive measure. High risk individuals such as those with a family history of colorectal cancer may even consider an earlier test.
How to prepare for the procedure?
- Before the procedure, special instructions about diet (low residue diet), medications and how to clean the colon (with laxatives and/or enemas) will be given to you.
- Do not eat or drink anything for 8 hours before the procedure.
- If you are taking anticoagulants, discuss with your attending doctor before discontinuing the drug.
What happens when the procedure is performed?
- You will be given a "sedative" through an intravenous (IV) line before the procedure begins. This medication will put you to sleep through the procedure.
- Then, a thin and flexible instrument called a colonoscope is inserted into the anus and guided through the colon.
- The colonoscope has a tiny camera with light source at its tip that allows the doctor to see the inside of the colon on a television screen as the scope is withdrawn.
- The colonoscope allows the doctor to take a biopsy or remove polyps during the procedure.
- During colonoscopy, air will be passed through the tube to distend the bowel. It is normal to have wind like cramps and a feeling of wanting to go to the toilet, which will gradually subside. Do not feel embarrassed. The procedure will last for approximately 30 minutes.
Must I do anything special after the procedure is over?
- After the procedure, passing gas helps relieve cramps. Inform your doctor if the discomfort persists, or if you experience severe abdominal pain or passage of blood per rectum.
- You must be accompanied by an adult when you leave because the intravenous sedation might make you dizzy. You must not drive, ride a bicycle, operate any machinery or drink any alcoholic beverage within 24 hours after the procedure.
- You can resume normal diet after colonoscopy.
The Centre is managed by a team of dedicated and experienced endoscopists. It is equipped with state-of-the-art endoscopic imaging systems and the aim is to provide high quality services in the diagnosis and treatment of diseases of the gastrointestinal tract, biliary and pancreatic system as well as the respiratory system. If necessary, during the procedure, the patient can be sedated with the help of our experienced anaesthesiologists to minimize any discomfort he/she might encounter during the procedure.
Our specialist will tell you right after the procedure what is seen in your colon. If biopsies are taken, it will take 2 to 3 working days to complete the report. Your specialist or attending doctor will contact you for subsequent follow-up and treatment.