Colonoscopy is a test to examine the inside of the bowel using a long thin tube with a camera at its tip. Colonoscopy is done by specialist doctors called endoscopists.
The main purpose of colonoscopy is to look for cancer or polyps, which are abnormal growths that could become cancer. Adenomas are the most common types of polyps.
Doctors will arrange for someone to have a colonoscopy (also called ‘a scope’) if they have symptoms of possible bowel cancer, if they have had a previous bowel problem, if bowel cancer runs in their family, or if they have had an abnormal result on a test ('faecal occult blood testA test that can detect microscopic amounts of blood in stools.') done as part of the National Bowel Cancer Screening Program or via their general practitioner or pharmacist.
Regular colonoscopy repeated every few years is recommended for some people. These include people who have previously had cancer, people who have had pre-cancerous polyps removed, some people who have inflammatory bowel diseases (IBD) and people with a strong family history of bowel cancer.These guidelines contain information for doctors about how to do colonoscopy, how often to do it and repeat it, and how to care for people when cancer or other bowel disease is found. These guidelines are an update of the 2011 guidelines for surveillance colonoscopy, and follow on from the current national bowel (colorectal) cancer guidelines, which were updated in 2017.
Improvements in colonoscopy
All medical tests sometimes miss the medical condition they are designed to detect. Colonoscopy picks up the vast majority (approximately 95%) of cancers and adenomas. Some endoscopists are better at finding growths than others – it takes training and practice.
Doctors and medical technicians are continually improving techniques and methods to make colonoscopy safer and more efficient. Areas of improvement include:
- how the bowel is emptied and cleaned out before a colonoscopy, including what the person is allowed to eat before the procedure and the timing of the preparation doses
- the medical instruments (colonoscopes) used, including the type of camera, electronics, attachments that improve the doctor’s ability to find abnormal growths
- the use of different dyes to help abnormal growths show up on the camera
- the way the endoscopist performs the colonoscopy
- how findings are recorded
- training methods for endoscopists.
Other methods, such as computed tomography (CT) colonography, do not use a camera inside the bowel. CT colonographyAlso known as virtual colonoscopy. is a type of scan done from the outside of the body.
Colonoscopy in people who have previously had polyps removed
How often a person needs a colonoscopy depends on what was found on their last colonoscopy and on other tests. These help doctors judge their risk of bowel cancer during the next few years. There are several different types of polyps. A person’s risk of developing cancer depends on the type.
When a polyp is removed, the pathologist tests it to work out exactly which type it is. This involves examining it under a microscope to look at the types of cells.
The recommended time to a person’s next colonoscopy could range from 1 year to 10 years, depending on the pathology report. Some patients may not need any further colonoscopies.
Colonoscopy for people with bowel cancer
Bowel cancer is often found during colonoscopy, before having a surgical operation to remove the cancer. If a bowel cancer is found in another way, colonoscopy is usually then recommended to check the remainder of the bowel. Sometimes, if the cancer blocks the inside of the bowel and prevents the camera passing through, another type of scan, such as a CT colonographyAlso known as virtual colonoscopy., may be used.
In most people after surgery for bowel cancer, colonoscopy should be repeated 1 year later. In some cases (if it was not completed before the cancer operation), colonoscopy might need to be performed 3 to 6 months after surgery.
After bowel cancer surgery and the repeated colonoscopy 1 year later, most people need regular follow-up colonoscopies long term. This may be continued for as long as the person is expected to benefit from repeatedly having their bowel checked, while taking into account their estimated life expectancy. How often these follow-up colonoscopies are needed depends on how many and what type of polyps are found at the first colonoscopy after surgery. The timing recommended is then according to polyp follow-up guidelines.
Colonoscopy for people with inflammatory bowel disease (IBD)
Inflammatory bowel disease (IBD) is a long-term medical condition that involves continual or recurring attacks of painful inflammation in areas of the bowel. There are two types of IBD: ulcerative colitis and Crohn’s disease.
Regular colonoscopy is recommended for many people with IBD, if their type of IBD increases their risk of bowel cancer.
When signs of IBD are discovered during colonoscopy, samples (biopsies) of abnormal bowel lining are removed to be examined under a microscope by a pathologist. The pathologist’s report and the findings of the colonoscopy help doctors work out the best treatment for the person, including whether they have a higher risk of bowel cancer.
For people with IBD, when and how often to have colonoscopy depends on their individual circumstances. For some people with IBD, colonoscopy should start as soon as they get the diagnosis. For others, the first surveillance colonoscopy is recommended 8 years after the symptoms began. Colonoscopy should be repeated at intervals (often every 1, 3 or 5 years) depending on the individual’s risk of bowel cancer. At each colonoscopy, the lining of the bowel is carefully inspected and small pieces of bowel lining (biopsies) are often removed for testing by a pathologist. Some people with IBD do not have an increased risk of bowel cancer and don’t require colonoscopy for the purpose of preventing bowel cancer.
Any suspicious-looking growths are removed during the colonoscopy, if possible. If growths cannot be removed during colonoscopy, the person may need to have bowel surgery. Colonoscopy is repeated more frequently after growths have been removed.
The person’s doctors will continually reassess whether to remove abnormal growths or just keep checking them from time to time.
Coping with colonoscopy
Having a colonoscopy can be stressful. It is common for someone to be a little anxious when they are about to have a colonoscopy. Most people do not experience severe anxiety.
A colonoscopy is usually done while the person has been given a strong sedative or a light anaesthetic. This helps people feel calm and relaxed during the procedure.
Doctors and nurses should carefully explain what will happen and what to expect. Written information or a video before the day of the colonoscopy can help people know what to expect and might help people cope better. Some people prefer to get more detailed information than others.
Improving bowel health for people living in poorer and more remote areas
On average, poorer people and people living in rural and remote places are more likely to die from bowel cancer. This may be because they are missing out on the best quality care. Aboriginal and Torres Strait Islander people, people living in remote and regional areas, and people living in poorer areas are less likely than other Australian to have colonoscopies recommended for them after they have an abnormal result on the screening test.
Hospitals, specialists and GPs should make extra efforts to promote access for these people to get the follow-up they need, including access to clear information and colonoscopy.
- Cancer Council Australia Colorectal Cancer Guidelines Working Party. Clinical practice guidelines for the prevention, early detection and management of colorectal cancer. Sydney: Cancer Council Australia; 2017 Available from: https://wiki.cancer.org.au/australia/Guidelines:Colorectal_cancer.