Colonoscopy Brochure

This A4 size brochure is produced by the Australian Government Department of Health and Ageing and the Gastroenterological Society of Australia. It is designed to provide information about the colonoscopy procedure.

Page last updated: 16 December 2018 (this page is generated automatically and reflects updates to other content within the website)

PDF printable version of Colonoscopy Brochure (PDF 143 KB)

Colonoscopy - Facts about

You have been encouraged to see your doctor in relation to your FOBT result. After a full consultation with your doctor, he or she may recommend that you have a colonoscopy. Colonoscopy is a procedure used to inspect the large bowel (colon).

This brochure is designed to provide you with some background information about colonoscopy, but your doctor will discuss colonoscopy with you in detail before you undergo the procedure. If you have any questions about colonoscopy, please ask your doctor.

How is the bowel prepared?

In order for your doctor to get the best possible view and make the colonoscopy easier, your large bowel needs to be cleaned out of all waste material. You will need a preparation kit which contains full instructions. Usually this involves a special diet for a day or two, consisting of no solid food, lots of clear fluids and laxatives the day before the procedure.

Take your regular medications on the day of the test.

Special considerations

The following medications should be stopped at least one week before the procedure: iron tablets, aspirin and anti arthritis drugs. Let your doctor know beforehand what medications you are taking, including over-the-counter items.

If you have diabetes or have heart valve disease or have a pacemaker implanted or are taking blood thinning tablets such as warfarin it is important to discuss this with your doctor before the colonoscopy is organised as special arrangements may be necessary.

You should have nothing to eat or drink for six hours before the procedure is done. However, you may have a sip of water with your regular medications.

You need to fast

Have nothing to eat or drink for six hours before the procedure is done. You should take your medications with a sip of water at the usual times.

Will I be given sedation or anaesthetic?

Yes. Before the procedure either a sedative injection or a light anaesthetic is given into the vein to make you comfortable, although you may still be awake throughout the procedure.

How is colonoscopy done?

The colonoscopy is performed while you lie on your side, although it is often necessary for you to lie on your back at some stage during the procedure. The instrument is inserted through the back passage. Most colonoscopies take between 20 and 45 minutes.

If you have any questions or concerns please talk to your doctor before the colonoscopy.

What is a polyp?

A polyp is a small growth attached to the bowel wall which over time can occasionally become a cancer. If polyps are found they are usually removed at the time of the examination. Most polyps are removed by placing a wire snare around the polyp and applying an electric current (diathermy).

If your doctor suspects that a polyp has already turned into a cancer, then usually a small sample, or biopsy, will be taken for examination. It will not be possible to discuss the removal with you during the examination as you will have had some sedation and may not be able to think clearly.

What happens after colonoscopy?

Following the procedure you will remain in the recovery area for approximately two hours until the effect of the sedation wears off. When you wake up you may feel a little bloated. This is due to the air that was inserted during the procedure. This will pass during the next hour or so. Very rarely, you may pass a small amount of blood. This is due to biopsies that have been taken and is of no concern. You may then go home. Because of the sedation given it is important that you do not drive a car, travel on public transport alone, operate machinery, sign legal documents or drink alcohol for 24 hours after your test.

It is strongly advised that a friend or relative takes you home and stays with you overnight.

Safety and risks

The colonoscope is completely cleaned between each patient to avoid the risk of transmission of serious diseases such as HIV/AIDS, hepatitis B or C. Even though colonoscopy has a high level of accuracy, there is a risk that an abnormality may not be detected. This risk is reduced if your bowel is well cleaned so the doctor has a good view. Serious complications of colonoscopy are uncommon at less than one in five hundred examinations. However complications can occur and include the following:
  • Intolerance of the bowel preparation. Some people develop dizziness, headaches or vomiting.
  • Reaction to the sedatives or anaesthetic. This is very uncommon but is of concern in people who have severe heart disease or lung disease.
  • Perforation (making a hole in the bowel wall).
  • Major bleeding from the bowel. This can occur as a result of polyps being removed.
If these serious complications occur you may require surgery or a blood transfusion.
  • Rare side effects can occur with any procedure. Death is a very remote possibility.
  • If you wish to have further details please discuss this with your doctor before the procedure.
  • If you have any of the following symptoms in the hours or days after colonoscopy you should contact the hospital or your doctor’s rooms immediately: severe abdominal pain, black tarry motions, persistent bleeding from the back passage, fever or other symptoms that cause you concern.


Your doctor will discuss the benefits and risks with you before you have a colonoscopy, and you have to give your permission before the colonoscopy can be performed. This should be discussed with your doctor or a staff member of the facility where you are having the procedure. If you have any questions in relation to the procedure, your doctor will be able to answer them. You can choose to have a colonoscopy in a public or private facility. If you have private health insurance, and are planning to have your colonoscopy as a private patient, you should talk with your doctor about where the procedure will take place and whether there will be any gap or out-of-pocket cost for you to pay to the doctor for the procedure. You should also check with your health fund before the procedure to find out what your health insurance will cover.

Getting your results

Your doctor will explain the results of your colonoscopy to you.

Your doctor will also be asked to provide the results of your colonoscopy to the National Bowel Cancer Screening Program Register. This information is protected by law (Privacy Act 1988) and your personal information will not be unlawfully disclosed.

Ask questions if you are not sure about any information you receive. You might like to take someone with you when you visit your doctor to discuss your procedure. Your doctor will be happy to answer any questions you have.

Where can I get more information?

You can get more information on:

The Program by telephoning the National Bowel Cancer Screening Program Information Line on 1800 118 868 or visiting the Cancer Screening website.

Bowel cancer by telephoning the Cancer Information Service on 13 11 20 or by visiting the Cancer Council Australia website.

This brochure has been developed in conjunction with the Digestive Health Foundation, the educational arm of the Gastroenterological Society of Australia website.

This brochure cannot be completely comprehensive and is intended as a guide only. The information given here is correct at the time of printing, but may change in the future. If you have further questions you should raise them with your doctor.

This page was last reviewed in March 2014.