What is a colonoscopy?

Colonoscopy is a procedure that examines the lining of the colon and rectum, and therefore is able to diagnose diseases of the colon and rectum. The colon, or large intestine, is the last portion of your digestive tract. It starts at the caecum and ends at the rectum. The colon is about 1.5 metres long. Checking the colon and rectum has become very important as colorectal cancer is the number 1 cancer in Singapore as well as in many developed countries. The colonoscopy is the most effective test for colon cancer.


Colonoscopy can detect cancerous growths, as well as detect and remove pre-cancerous polyps. By removing such pre-cancerous polyps, we can potentially prevent cancer.


This procedure uses a highly advanced flexible tube called the colonoscope. The colonoscope has a light source and a tiny high-definition video camera attached at its end.


The doctor will insert this flexible tube, which is about the diameter of the index finger, through the anus into the large intestine. You will be given some drugs to make you sleep and hence you will be quite comfortable during the procedure. You may not even be aware of the procedure.


As the doctor inserts in the colonoscope, he will be watching a monitor. The images from the camera are transmitted and magnified onto a high-definition monitor. This allows the doctor to see exactly the inside of your colon and rectum, including very small abnormalities due to the magnification.


Besides diagnosing diseases, the colonoscope can be used to treat certain problems. It can be used to stop bleeding from ulcers or tumours.  It can be combined with rubber band ligation of piles. It can even be used to perform minor surgery such as cutting out small tumours like polyps or even early cancer.

When would the doctor recommend a colonoscopy to a patient?

Some of the common symptoms or problems that will cause the doctor to recommend a colonoscopy includes:


Lower abdominal pain

Irregular bowel habit

Change of bowel habit

Change of stool consistency

Chronic constipation

Recurrent diarrhoea

Bleeding in the stools

Stools becoming pencil-thin in diameter

Feeling of incomplete evacuation after passing motion

Mucus-like discharge from the anus

Persistent ulcers or infection around the anus

Unexplained weight loss

Unexplained appetite loss

Anaemia (the patient’s haemoglobin level is low)

Screening for colon cancer in high-risk individuals

Faecal occult blood test positive for blood


How is a colonoscopy like?   

Before the Colonoscopy 
  • The doctor will first take an informed consent during which he / she will describe the procedure, the benefits as well as the risks involved, as well as alternative methods to check the colon.
  • Prior to the colonoscopy, you will be prescribed some medications to thoroughly clean out the colon. By cleansing the colon, the doctor will have a good view of your colon. It is essential that you complete this preparation fully as this will determine how well your doctor can examine your colon.
  • You will be asked not to eat or drink anything from two to six hours before the colonoscopy.
During the colonoscopy
  • The colonoscopy is typically performed at the Endoscopy Centre.
  • At the Endoscopy Centre, the nurse will insert an intravenous cannula into a vein at your hand so as to allow us to administer the drugs to sedate you.
  • Your parameters (blood pressure, heart rate and blood oxygen level) will be monitored before, during and after the procedure.
  • You will be asked to lie on your left side.
  • Once you are fully sedated, your doctor will gently pass the scope into your colon.
  • As the scope is advanced, air will be introduced so as to allow the doctor to see better. You may therefore experience bloating. You may also feel as if you need to pass motion as the scope advances in your colon. Our nurses may sometimes apply pressure on your abdomen to help the doctor in advancing the colonoscope. Otherwise you should feel little or no discomfort.
  • The colonoscope has channels that allow the doctor to obtain biopsies (small pieces of tissue) or perform other treatments (such as removal of polyps), depending on what is found during the examination.
  • The time needed for a colonoscopy will vary, depending in part on what is found and what is done. On average, the procedure takes about 30 minutes.


After the colonoscopy
  • Colonoscopy is usually performed as a Day Surgery procedure.
  • The most common discomfort after colonoscopy is a sensation of bloating, which should disappear by 24 hours.
  • You will need to stay at the Recovery area for monitoring for at least 1 hour. Some light refreshments will be served once you are fully awake.
  • When you are fully awake, your doctor will discuss with you the findings of the colonoscopy. This may be done in the Endoscopy Centre or in our Nexus clinic. Otherwise, an early date will be given to you to return for a consult with your doctor.
  • It is essential for you to arrange for a friend or family member to accompany you home. Although you will be awake by the time of discharge, the sedatives may have a lingering effect.

Is a colonoscopy a safe procedure?

The colonoscopy is a very safe procedure. Nonetheless, although very rare, complications can occur. The overall complication rate is about 2-3 in 1000 patients. These complications include bleeding, perforation or injury of the colon walls.

How much does a colonoscopy cost?

The estimated cost for a colonoscopy is divided into 2 components: the doctor’s fees and the hospital fees. The hospital fees refer to charges levied by the hospital for the use of the instruments as well as the ward / bed and nursing care.


The doctor’s fees for a diagnostic colonoscopy performed during office hours by Nexus Surgical Associates doctors will be approximately S$1000 to S$1500 (excluding taxes).


For Singaporeans and Permanent Residents, Medisave may be used to pay part of or all of the bill (conditions apply). As for patients wishing to claim from their health insurance policies, it is best to enquire with your insurance agents first.

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