Colonoscopy/ Endoscopy

What is colonoscopy?

This procedure involves a colonoscope – a long, thin flexible tube with a ‘video camera’ at the tip – being passed through the rectum into the colon. It allows for inspection of the lining of the large intestine and also for procedures such as biopsies and removal of polyps.

What is colonoscopy?

Colonoscopy can detect inflamed tissue, ulcers and abnormal growths including polyps. The procedure is used to look for early signs of colorectal cancer and can help doctors diagnose unexplained changes in bowel habits, abdominal pain, weight loss and bleeding from the bowel. It also allows for treatment of certain conditions (eg. banding of bleeding haemorrhoids). In some individuals with a family history, this may also be an appropriate test to check for polyps and bowel cancer.

How do I prepare for colonoscopy?

For a successful colonoscopy, it is essential to empty the bowel thoroughly of all waste material, which can be done by taking a bowel preparation. Failure to do this prior to colonoscopy may mean it is not possible to see important markers or polyps, and you may have to return for another procedure.

A complete bowel preparation consists of:

1. Modifying your diet

This will involve following a special diet for several days prior to the colonoscopy

2. Taking a bowel preparation medication

This causes diarrhoea and empties the colon. The diarrhoea can cause irritation around your bottom.
Using a barrier cream (eg. Calmoseptine / Sudocream / Pawpaw ointment / Vaseline) around your anus will help prevent this. Moistened, alcohol-free wipes (eg. WetWipes / WetOnes) may be more soothing than regular toilet paper.
Occasionally, people may be intolerant to the bowel preparation medication and experience headaches or vomiting.

3. Increasing your fluid intake in the days prior to the procedure

Specific preparation instructions will be given to you.

Please inform your doctor of all medical conditions (eg. heart disease, diabetes, heart surgery or stents, pacemakers) and all medications (especially insulin and diabetes tablets, and blood thinners such as Warfarin, Aspirin, Clopidogrel, Eliquis, Xarelto, Pradaxa)

How is a colonoscopy performed?


Before the procedure a light anaesthetic (sedative) is given – you will not receive a full general anaesthetic. Very rarely, you may be slightly aware of what is going on in the room, but generally you won’t remember anything. For safety, an anaesthetist will administer the sedation, monitor your vital signs during the procedure and make you as comfortable as possible.

Examination of the bowel

Once sedated and lying in a comfortable position on your left side, the doctor inserts the flexible colonoscope (‘scope’) through the anus and slowly guides it into the colon. A small camera in the end of the scope transmits a video image to a monitor, allowing the doctor to carefully examine the intestinal lining. Once the scope has reached the opening to the small intestine, it is slowly withdrawn and the lining of the large intestine is carefully examined again.

Removal of polyps and biopsies

A polyp is a small tissue growth attached to the bowel wall. These are common in adults and are usually harmless. However most colorectal cancers begin as a polyp so removing them early is an effective way to prevent cancer. If polyps are found during the procedure they will usually be removed using tiny tools (‘snares’) passed through a channel in the scope. Small tissue samples or biopsies of the bowel may also be taken for examination. All samples taken are sent of for assessment under a microscope (histopathology).

What happens after a colonoscopy?

Following the procedure you will remain in the recovery area for an hour or two until the sedation medication wears off. You will be given something light to eat and drink once you are awake.

When you wake up you may feel a little bloated, but this should pass over the next hour or so. Very rarely you may pass a small amount of blood. This is often due to irritation of the anal canal on insertion of the scope or due to biopsies, and this shouldn’t concern you.

Because of the sedation given, it is very important that you do not drive a car, travel on public transport alone, operate machinery or sign legal documents on the same day after your procedure. It is strongly advised that an adult family member, relative or friend take you home and stay with you that night. Full recovery, and return to normal activity is expected by the next day.

Are there any risks or side-effects?

Although complications can occur, they are rare. In Australia, very few people experience serious side-effects from colonoscopy and polyp removal (less than 1 in 1000). The chance of complications depends on the exact type of procedure that is being performed and other factors including your general health.

Major bleeding after colonoscopy is rarely seen, but if occurs may require readmission to hospital, often a blood transfusion, and occasionally a repeat colonoscopy.

Very rarely (less than 1 in 2000-3000) the bowel lining may be injured/ torn. If this occurs you will be admitted to hospital for antibiotics. An operation may be required to repair it.

Reactions to the sedative are also possible, but again rare.

In a few cases, if the colonoscopy is not successfully completed (either due to poor preparation or technical difficulty) it may need to be repeated.

If you have any of the following symptoms in the hours or days after the colonoscopy you should contact your doctor’s rooms immediately or present to the nearest emergency department:

  • Severe abdominal pain
  • Black, tarry motions
  • Persistent bleeding from the anus
  • Fever
  • Other symptoms that cause you concern

How accurate is colonoscopy?

Colonoscopy provides the most accurate assessment of the lining of the colon. However, no test is perfect and there is a risk that an abnormality may not be detected.

A colonoscopy can miss serious lesions in the bowel in 2% – 8% of cases. For serious lesions such as cancer, the chance is extremely low, but still present. If you have any recurrent or persistent symptoms after your procedure, please advise your doctor.