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Waitematā DHB Gastroenterology Services

Public Service, Gastroenterology & Hepatology (Liver)


This is a procedure which allows the doctor to see inside your large bowel and examine the surfaces directly and take biopsies (samples of tissue) if needed.  Treatment of conditions can also be undertaken.
What to expect
The colonoscope is a flexible plastic-coated tube a little thicker than a ballpoint pen which has a tiny camera attached that sends images to a viewing screen. You will be given a sedative (medicine that will make you sleepy but is not a general anaesthetic). The tube is passed into the rectum (bottom) and gently moved along the large bowel.  The procedure takes from 10 minutes to 1 hour and your oxygen levels and pulse rate are monitored throughout.
Before the procedure
You will need to follow a special diet and take some laxatives (medicine to make you go to the toilet) over the days leading up to the test as the bowel needs to be completely clean for the procedure.
Risks of a colonoscopy are rare but include:     
  • bleeding if a biopsy is performed          
  • allergic reaction to the sedative
  • perforation (tearing) of the bowel wall.

The risk of a significant complication is about 1 in a 1000 procedures.

This page was last updated at 4:00PM on September 6, 2021.