What is a colonoscopy?

A colonoscopy is a medical procedure that uses a flexible tube known as a colonoscope. The tube is gently inserted into your anus and passed through the rectum into the large bowel (colon).

The tube has a tiny camera and light at the end. The tube is long, thin and flexible. This means it can bend and move around the curves of your bowel to give a clear view of its entire length, which is displayed on a screen. This allows your doctor to examine your large bowel, and even take samples of tissue (biopsies) if necessary with special instruments attached to the colonoscope.

When is a colonoscopy recommended?

Your doctor or gastroenterologist may recommend a colonoscopy:

• to find the cause of gut-related problems such as abdominal pain or bleeding from the anus
• if you have a high risk of bowel problems due to chronic bowel disease or a family history of bowel disease, such as bowel cancer
• if your gastroenterologist suspects you might have polyps or inflamed tissues in your bowel
• to find the cause of unexplained weight loss or stool (poo) changes
• to follow up any suspicious findings of a previous colonoscopy
• if you have had a positive bowel cancer screening test (poo test)

Ask your doctor about your risk of developing bowel cancer.

Where can I get a colonoscopy?

You can have a colonoscopy at a public or private hospital or clinic.

If you are treated as a public patient in a public hospital, you won't usually have any out-of-pocket costs.

If you choose a private hospital or choose to be treated as a private patient in a public hospital you might have to pay, depending on your level of private health insurance. Ask your insurer out about any out-of-pocket costs, waiting periods, and what facilities are available.

How do I prepare for a colonoscopy?

Before a colonoscopy you need to prepare your bowel to make sure the procedure goes smoothly. Preparation can be different for each person and depending on your hospital's protocol.

Go over the instructions for your colonoscopy at least two weeks ahead of time. Make sure you know what to do with your diet and medicines, especially if you have:

• diabetes
• kidney disease
• high blood pressure
• heart or blood vessel conditions
• use blood thinners
• other serious medical conditions

You will receive instructions from your doctor or hospital before the procedure. It's important to follow these instructions so you don't have to redo the test. Here's what you need to know about the preparation process.

Dietary changes

A few days before the procedure, you may need to avoid high-fibre foods such as:

• fruits and vegetables
• brown rice
• wholegrain pasta
• cereal
• nuts and seeds

Instead, you can eat low-fibre foods such as:

• white rice and white bread
• chicken and fish
• yogurt and cheese
• potatoes and pumpkin

Your doctor may advise you to drink only clear fluids for 12 to 24 hours before the test. Examples of clear fluids are:

• water
• clear fruit juices without pulp — check with your clinic what is acceptable
• black tea or coffee (without milk)
• clear soup

It's important to drink plenty of fluids before your colonoscopy to avoid dehydration.

Bowel preparation

You may be prescribed medicine to take 12 to 18 hours before the procedure that. It causes watery diarrhoea that will help empty your bowel.

Sometimes, you might need to use an enema. This means inserting liquid into your rectum to wash out the lower bowel. The enema solution and any poo will be passed into the toilet.

You might have mild side effects from the bowel preparation such as:

• nausea
• bloating

Take a short break if you experience any mild side effects. More serious side effects include:

• dizziness
• fever
• severe headache

These side effects might mean you have dehydration or an allergic reaction to the bowel preparation. Contact your doctor if you have any serious side effects or if you cannot finish the bowel preparation.

Your regular medicines

Ask your doctor about whether to continue taking your regular medicines in the days before and after your procedure, especially if you take blood-thinning medicines.

This includes:

• prescribed medicines
• over-the-counter medicines
• herbs or supplements

What happens during a colonoscopy?

The colonoscopy usually takes less than 30 minutes. You will typically receive a general anaesthetic or sedation to minimise pain or discomfort. This means you won't usually remember the procedure.

During the procedure

You will lie on your left side and receive sedation before the procedure starts. The doctor will insert a thin, flexible tube into your bowel. The colonoscope has a light and camera to help the doctor see inside your bowel.

Air is pumped into your bowel to make it easier to see the bowel walls. Your doctor might remove any polyps (small tissue growths) they find, and take biopsies (small samples of tissue) to check for disease.

The procedure usually takes place as day surgery, so you won't need to stay overnight. You will stay in a recovery area until your sedation wears off.

After the procedure

After your colonoscopy your doctor will give you a short update. You may not get the full results until a later follow-up appointment.

You may feel sleepy after the procedure due to the sedation or anaesthetic. You will need somebody to help you get home. It is also a good idea to have someone stay with you the night after your procedure. Straight after sedation, you should not:

• drive a car
• travel alone on public transport
• use machinery
• sign legal documents
• drink alcohol

You should feel better the next day. Your doctor or nurse will give you instructions on how to look after yourself at home including:

• when to start taking your regular medicines again
• what to eat and drink
• what to do if you have any problems

What does a colonoscopy feel like?

A colonoscopy is a quick and generally painless procedure. Most people prefer to be sedated during a colonoscopy. This means you usually wake up in the recovery room without remembering the procedure.

Since you don't have pain nerves inside your bowel, you won't feel it if any polyps or tissue are removed. During the procedure, the doctor will inflate your bowel with air to help them get a good view of the bowel walls. This can cause bloating that usually resolves within 24 hours.

What side effects or complications can occur after a colonoscopy?

After a colonoscopy you might feel:

• tired from the sedation
• bloating because of trapped air in your bowel
• mild discomfort

If polyps were removed, you may have some mild bleeding from your rectum or in your bowel motions (poo). This can start straight away or within two weeks.

Complications during or after a colonoscopy are rare and include:

• bleeding
• perforation (poking a hole in your bowel)
• infection
• dehydration or an allergic reaction to the bowel preparation
• complications from medicines used for sedation

Call your doctor immediately if you have:

• a fever
• more than a tablespoon of rectal bleeding
• severe abdominal pain or bloating
• persistent nausea or vomiting
• extreme thirst
• dizziness
• headaches

It's also possible to have a polyp or cancerous growth in your bowel that isn't detected with colonoscopy. Despite this small risk, colonoscopy is still the best method available to screen for bowel cancer.

Are there alternatives to a colonoscopy?

A colonoscopy is the best way to check for bowel cancer. There are other tests such as a:

• Virtual colonoscopy — uses MRI or CT scans to create images of your bowel. It is not as accurate because it can't take tissue samples or see smaller issues. You will still need a colonoscopy if something abnormal is found.
• Flexible sigmoidoscopy — looks at the rectum and lower part of the bowel only. It's less thorough than a colonoscopy.
• Bowel screening test — is recommended every two years if you are at average or slightly above average risk of bowel cancer. This test checks your poo for tiny traces of blood that you can't see. Blood in your poo can be a sign of polyps or bowel cancer.

Resources and support

For more information on how to receive a bowel screening kit, visit the National Bowel Cancer Screening Program.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

Do you prefer to read in languages other than English?

The National Bowel Cancer Screening Program offers translated information in several languages.

Looking for information for Aboriginal and/or Torres Strait Islander people?

The Department of Health and Aged Care provides bowel screening information for Aboriginal and/or Torres Strait Islander families and communities

SA Health has culturally appropriate information on bowel screening for Aboriginal women and Aboriginal men.

Cancer Australia also has a range of bowel screening resources for Aboriginal and Torres Strait Islander people and health professionals.