Colonoscopy is a surgery to examine the lining of the large intestine. Using a flexible endoscope that passes through the patient’s anus, the doctor can check if there is any inflammation, bleeding, ulcer, polyp or tumor in the large bowel and sometimes the distal small bowel as well. The doctor can also remove polyps or take a sample of the lining for testing. It is effective in screening of colorectal cancer, and also in cancer prevention, as it can remove polyps before they develop into cancer.    

You should consult your doctor whether you need a colonoscopy if you have family history of colon cancer, or symptoms such as:

• chronic persistent pain in the lower abdomen
• change in bowel habits; over 50 years old
• chronic diarrhoea or constipation
• feeling of incomplete bowel movement
• unexplained weight loss
• bleeding from the anus or blood in stool    
  

You should have no-fibre diet for 3-4 days before the surgery according to your doctor’s instruction. The doctor will instruct you to take a laxative to clear out the bowel, and may ask you to follow a clear liquid diet (e.g. clear broth, strained juices and sport drinks) before taking the laxative. Please follow the doctor’s instructions closely, because if your bowel is not completely empty, the doctor may not have a clear view of your bowel. In this case you might have to undergo the surgery again. If you experience any uncomfortable feeling that prevents you to continue with your preparation, please contact your doctor for advice.

You also need to sign a consent form to confirm that you understand the surgery and risks involved as explained by your doctor. You must inform your doctor if you have any chronic illness, drug allergy, or are taking any regular medication.

Firstly you will lie on your left side with your knees brought toward your chest. The doctor will give you a sedative injection, and maybe also painkiller. Then the doctor will gently insert the endoscope through the anus, and move it until it reaches the other end of the large intestine and sometimes up to the distal small bowel. Your abdomen may feel bloated and mild cramp after this process, but it usually disappears in a few hours. Nurses may adjust your posture so that the endoscope can be moved smoothly.  Monitored anaesthetic care (MAC) may be required for fragile elderly, young kids or teens. People used to alcoholic drinks or sleeping pills or those request absolute amnesia of the surgery may need MAC as well.

The endoscope is a thin tube-like instrument with fibreoptics. During the surgery, the doctor might pump in air for a better view. The whole surgery takes about 20-30 minutes if no major abnormality is found.    

You may need a short rest of half an hour at the clinic, depending on your dose of sedative. Therefore, we suggest you have an adult accompany when you leave the clinic. Also you should not drive or consume alcohol for 24 hours afterwards.

You can eat and drink normally about two hours after the surgery. Please make sure to drink plenty of liquid and eat a healthy meal to restore your energy.    

Colonoscopy is a generally safe surgery with low risk. Possible complications include reaction to the sedative, internal bleeding, tearing or rupturing of the colon wall; such cases are rare.