What is a colonoscopy?

A colonoscopy is a procedure that enables the doctor to see inside your large bowel/colon through your back passage. A fibreoptic tube (colonoscope) is used to visualize the surface of the bowel. The bowel is opened up ahead of this tube using gas insufflations. This is why you may feel bloated after the procedure and may pass wind. The colonoscope is also equipped with suction to help clear the bowel from liquid content allowing visualization of the surface.

Suction mainly works for liquid content which is why you are asked to prepare your bowel so that it only contains liquid motions. Suction channels can be easily blocked with seeds which is why we ask you to avoid foods with grains or seeds five days prior to your procedure.


A tissue sample or biopsy may be obtained at the time of colonoscopy. Polyps (growths) are removed (polypectomy). Biopsies and polyps are sent to the pathologist. This is done by passing special forceps, or snare through the colonoscope and removing the polyp from the bowel wall. Taking biopsies or removing polyps causes no discomfort.

What are the risks of colonoscopy?

Following a colonoscopy, bleeding can occur from a biopsy site or more commonly following a polypectomy. This usually stops on its own and does not require admission to hospital.

Significant bleeding requiring admission to hospital may occur in up to 2 in 100 patients.

Perforation is a hole in the bowel that may require surgery. The risk is small (1 in 1000).

Before your procedure

Preparation for your colonoscopy starts almost a week before with some dietary restrictions and possible changes to your medication which will doctor will discuss with you prior to your colonoscopy.

STOP eating anything with seeds, grains, wholemeal, nuts or dried fruits – 5 days before colonoscopy.

  • STOP all iron containing medication 5 days before your colonoscopy.
  • If you take the oral contraceptive pill, use alternative contraception for 7 days starting the day before colonoscopy as the pill’s absorption may be affected.
  • On the morning of your colonoscopy, take your regular medications with a sip of water even if fasting.
  • If you are on blood-thinning medication, these may have to be withheld prior to your procedure. Please discuss this with your doctor.
  • If you are a diabetic, your medication doses may be changed on the day before your colonoscopy. Please discuss this with your doctor.

Bowel preparation

For a colonoscopy to be successful, your bowel must be completely clean. This is achieved by carefully following the dietary restriction and drinking your bowel preparation.

Bowel preparation solution is purchased from the pharmacy without a prescription. It works by washing the bowel through giving you diarrhoea.

The type of bowel preparation depends on a number of factors including your age and whether you have any kidney / heart / liver disease. You may need an extended bowel preparation if you have had a failed colonoscopy or suffer from severe constipation.

Dietary restrictions and the bowel preparation schedule depend on the timing of your colonoscopy – Morning vs Afternoon procedure.

To find out which bowel preparation schedule you should follow, please answer the following questions. When you press “Submit”, you will be guided as to which bowel preparation option to download and follow.

Bowel Preparation Options

After your colonoscopy

Bloating of the stomach and passing wind for a while is normal. It is important to drink plenty of water daily to prevent constipation and ensure adequate fibre in diet. This also aids to replenish fluid loss lost during your bowel preparation.

Taking Panadol or drinking peppermint tea can relieve the symptoms of abdominal cramps. If persistent, notify the doctor. Rest and lying on the left side can assist in “wind” being expelled.