What is the Purpose of Colonoscopy?

To examine the lower gastrointestinal tract (colon or large bowel), to remove polyps (small benign growths), inject bleeding blood vessels, and to take samples of tissue (biopsies) for examination by a pathologist. Colonoscopy is the most reliable method of bowel examination but small abnormalities including cancers can very occasionally be missed.

How are you Prepared?

Prior to the procedure you will be given a bowel preparation kit with instructions. The bowel preparation cleans the colon. Without this it is not possible to perform a full examination of the colon. Although the bowel preparation is unpleasant, it is very rare for it to be harmful. If you have had difficulties with the preparation in the past, or if you have severe heart, lung, or kidney disease you should discuss this with the doctor.

How is Colonoscopy Done?

A long, thin flexible tube is passed around the bowel from the anus. This takes about 15 minutes and is done under intravenous sedation (Midazolam, Fentanyl, and sometimes Propofol). Reactions to these medications are rare. After the procedure you must not drive or use machinery until the next day, or longer if you feel unsteady or tired the next day. If you object to the use of sedation please discuss.

Colonoscopies are done in a hospital, usually on a day case basis. You would be required to attend the hospital for about 3 hours if you have sedation for your colonoscopy. You will need to arrange transport to and from the hospital.

Are there Alternatives to Colonoscopy?

A barium enema x-ray of the bowel will give similar information but it is not as accurate for certain problems, it does not allow biopsies or removal of polyps. It does not require sedation or hospital admission.


Colonoscopy and polypectomy are very safe. Serious complications are rare. These include:

  • Reaction or sensitivity to medication used for sedation (this may affect your breathing briefly)
  • Perforation (puncture) of the lining of the bowel (about 1 patient in 2000-5000)
  • Bleeding - if blood vessels are injected or a polyp is removed (about 1 patient in 300-500)
  • Infection of the bowel, blood, and other organs
  • Heart attacks, cardiac arrest, blood clots, and breathing problems (very rare)
  • There are other very rare complications - please advise if you wish to be given more details

Everything will be done to minimise the risk of these complications. There are ways of detecting these complications early and specific treatments are available if they do arise. Very rarely there may be a need for hospitalisation, major surgery, intravenous feeding, or blood transfusion. Although death can result from complications of colonoscopy this is very rare.

Special Precautions will need to be taken:

  • if you suspect or know you are pregnant or if you are breastfeeding
  • have severe heart, lung, or kidney disease
  • have lymphoma, leukaemia, or you are receiving chemotherapy
  • if you have had heart valve disease, a pacemaker, aortic graft or other blood vessel graft
  • if you bleed very easily or if you take blood thinning tablets (warfarin), aspirin, or arthritis tablets
  • if you are allergic or sensitive to any medication