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What is a colonoscopy?

Colonoscopy is a procedure where a flexible tube about the size of the index finger is used to look inside the colon. It is performed by an endoscopist, who is a doctor with special training in endoscopy. This flexible tube, called the colonoscope, has a tiny video camera and a light source at its end. The high-quality and magnified image from the colonoscope is transmitted to a monitor so that the doctor can see even small changes in the lining.

What is a sigmoidoscopy?

A sigmoidoscope can be thought of as a shorter version of the colonoscope. There are 2 types, a rigid type made of a hollow metal tube, as well as a flexible type, much like the colonoscope. This is used to evaluate the lower part of the colon only.


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.

The colonoscopy allows the doctor to visualise the lining of the colon and come to a diagnosis of your condition. The colonoscope can also be used to treat certain conditions. This is the therapeutic function of the colonoscope.

The colonoscope is used to obtain a diagnosis for the following symptoms or conditions:

  1. Blood in your stools
  2. Abdominal pain
  3. Chronic diarrhoea
  4. Change in bowel habits
  5. Abnormality found on X-ray or a CT scan
  6. Screening for colon cancer
    For individuals with previous history or family history of polyps or colon cancer

The colonoscope can be used to treat the following conditions:

  1. remove small polyps (polypectomy)
  2. remove small and early stage colonic tumours
  3. stop bleeding from ulcers or tumours
  4. treat or dilate strictures (narrowed areas in the colon) via colonic stenting
  5. ligate piles / haemorrhoids

Your doctor will first take an informed consent during which he will describe the procedure, the benefits as well as the risks involved, as well as alternative methods to evaluate the colon. 

This excellent 3D medical animation produced by Nucleus Medical Media demon-strates a colonoscopy procedure.       

This is what the endoscopist sees during an ac-tual colonoscopy.

Our nurses will provide you with instructions on how to prepare yourself for the colonoscopy.

Prior to the colonoscopy, you will be prescribed some medications to thoroughly clean out the colon. It is essential that you complete this preparation fully as this will determine how well your doctor can examine your colon.

Our nurses will dispense the required medications for bowel cleansing. They will give you a detailed schedule on when to take these medications and how to coordinate them with your meals.

You will be asked not to eat or drink anything for six hours before the colonoscopy.

Following your registration, you will be led to a bed where you will be asked to change into a gown. An intravenous cannula will be placed into your hand to allow your doctor to administer the sedatives for your procedure. You will be sedated for the procedure so that you are comfortable throughout. Your parameters (blood pressure, heart rate and blood oxygen level) will be monitored.

You will be asked to lie on your left side. Once you are fully relaxed, your doctor will first do a rectal exam; then the lubricated colonoscope will be gently inserted.

As the scope is advanced, you may feel as if you need to pass motion, and because air is introduced to help advance the scope, you may feel some cramping or fullness. Our nurses may sometimes apply pressure on your abdomen to help the doctor in advancing the colonoscope. Generally, however, there is little or no discomfort.

The endoscope contains channels that allow the doctor to obtain biopsies (small pieces of tissue) and remove polyps (polypectomy). This does not hurt since the lining of the colon does not sense pain. Removal of such polyps is also an important way of preventing colon cancer.

The time needed for colonoscopy will vary, depending in part on what is found and what is done. On average, the procedure may take about 30 minutes.

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 for 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. In addition, your ability to make decisions may be impaired.

Although colonoscopy is a safe procedure, complications can occur. These include:

  1. Perforation or puncture of the colon walls
    This is rare and happens in about 1 in 1000 patients
  2. Bleeding

The alternatives include:

  1. Barium enema
  2. CT Colography.

Both these tests are X-ray tests of the colon. If any abnormalities are found, the patients will require a colonoscopy for further evaluation and to allow a biopsy to be taken.

The answer is yes. This allows patients to have both their upper and lower intestines evaluated on the same day. The risks of these procedures are not increased just because they are done on the same day. Both can be safely done on the same day.

The bill 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.

The doctor’s fees for a diagnostic colonoscopy performed during office hours by Nexus Surgical Associates doctors will be approximately S$800 to S$900 (excluding taxes).

For Singaporeans and Permanent Residents, Medisave may be used to pay part 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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