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What is colonoscopy?

Colonoscopy is a safe and effective way of visually examining the lining of your lower gastrointestinal tract (colon and the end of your small intestine).

A colonoscope is a thin, flexible tube with a video camera and light at its end. Using various controls on the instrument, your specialist is able to guide the camera so as to carefully examine the lining of your bowel. Depending on the findings and the indication for the colonoscopy, biopsies (small tissue samples) may be taken, polyps (small growths) may be removed and in some instances, therapy may be delivered.

What is the reason for having a colonoscopy?

Colonoscopy can be performed for a variety of reasons, both to diagnose, evaluate, and treat conditions of the lower gastrointestinal tract. Common reasons for undergoing colonoscopy include a change in your bowel habit, rectal bleeding, and screening for colonic polyps or bowel cancer.

What are the risks of colonoscopy?

Colonoscopy is a generally safe procedure that is commonly performed and complications are rare.  Your doctor will discuss the risks and benefits with you and answer any question or concerns that you may have.

Common side-effects

Temporary side-effects following colonoscopy include a sense of abdominal bloating related to the use of air to inflate your bowel. You may also feel nauseated or sleepy due to the effects of the anaesthetic medications.


Perforation. 1:1,500 cases. Perforation is a hole or tear in the bowel wall that may require an operation to repair.

Bleeding. Bleeding can arise at a polypectomy or biopsy site. Most bleeding is minor and requires no treatment but occasionally (1 in 700) bleeding will require a repeat colonoscopy, blood transfusion, hospitalisation, or surgery.

Infection. The colonoscope is a reusable instrument that is stringently disinfected, however there is a very small risk of infection being introduced during the procedure.

Failure of procedure. The colonoscopy may be unsuccessful (e.g. technical issues or bowel preparation) and may need to be repeated.

Reaction to anaesthetic drugs. Rarely patients may have a reaction to the sedation.

Aspiration. Although uncommon, it is possible that whilst sedated you can vomit and aspirate the contents into your lungs.

Missed lesions. There is a chance that important lesions, in particular bowel cancers and polyps, may be missed at colonoscopy. The risk of missing a lesion is between 2% and 8%.

Death. Death is extremely rare (1 in 130,000), although is a remote possibility with any interventional procedure.

How do I prepare for the procedure?

Bowel preparation is required to empty the large bowel of faeces to ensure adequate visualisation of the lining of the bowel. If your bowel preparation in inadequate, the examination may be unsuccessful, and a further procedure will be required.

Please read our full Colonoscopy Preparation Instructions.

What do I do with my usual medications prior to the procedure?

Please inform your specialist if you are taking blood thinning or diabetic medications. You will be given specific instructions on the use of these medications prior to your procedure.

Your other regular medications should be continued unless your specialist provides you with specific instructions otherwise. Medications required on the morning of the procedure can be taken with a sip of water.

What happens on the day of the procedure?

You will be given an appointment time to come into hospital.  Prior to your procedure you will be seen by both nursing staff and your anaesthetic doctor, who will ask for further information regarding your past medical history, medications and any allergies that you may have. You will be asked to sign a consent form for the procedure if you have not already done so. You will also have a chance to see your Gastroenterologist prior to the procedure to discuss any questions that may have arisen.

What happens during the procedure?

We will make every effort to ensure that you are as comfortable as possible during your procedure. You will be asked to change into a hospital gown and then brought into the procedure room for your colonoscopy. A small drip needle will be inserted by your anesthetist, through which sedation will be given to make you comfortable during the test. Your vital signs (oxygen levels, blood pressure, and pulse) will be closely monitored whilst you are undergoing the procedure. Your specialist will examine your lower bowel using the colonoscope, and if necessary perform biopsies or removal of polyps.

How long does a colonoscopy take?

The time taken for colonoscopy varies, but is most often between 20 and 40 minutes. Colonoscopy is usually a day procedure so you will not need to stay in hospital overnight.

What happens after my colonoscopy?

You will be taken to the recovery area, where you will be closely observed by nursing staff as you recover from your anaesthetic. Once awake, you will be given something to eat and drink.  Your specialist will speak with you to inform you of your results and of the need for a follow-up test or appointment.

Going home after my colonoscopy?

You will be ready to go home from hospital around 2 hours after your procedure.

Due to the sedative medications given, you must not drive a car, operate heavy machinery or sign any important documents for 24 hours after the procedure.  Therefore, please arrange for someone to pick you up in order for you to go home.  You will also need a responsible adult to stay in the house with you the night after the procedure.

Most patients do not have any problems after colonoscopy, however if you experience any abdominal pain, rectal bleeding, fever or chills, or other concerning symptoms, then it is important that you seek medical attention immediately.

Further information about colonoscopy?

Further information on colonoscopy can be found through our information sheets or the Gastroenterological Society of Australia website:

GESA Colonoscopy Fact Sheet

Bowel preparation for colonoscopy information sheets