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In order to obtain a clear view, it is important that the bowel is thoroughly cleaned of all residue. Patients usually report that this is the most unpleasant part of the procedure. You will need to follow a special diet and drink a quantity of "bowel prep" solution. The procedure will take place in Brisbane and be completed by Dr Renaut.

So that a good view is obtained at the time of the procedure all faecal material should be removed from the colon and rectum. You will be restricted to clear fluids only for the whole day prior to your procedure up to midnight. From midnight through to two hours prior to the procedure you can drink water only. You must then be nil by mouth from then on until after the procedure. You will receive specific instructions about this well in advance of the procedure, including an admission time and an approximate time for the procedure itself. Additionally, comprehensive instructions, including potential side effects, are available.

What about my usual medications?

In general, these should all be taken as usual with a sip of water. Exceptions will include:

  • Warfarin or other blood thinning drugs
  • Insulin or other diabetic tablets.
  • Iron supplements.
  • Any herbal and naturopathic drugs - many of these contain unidentifiable substances in unknown quantities which make them potentially unsafe. They should be ceased at least one week prior to the procedures. You will need to check with the manufacturers as to what these contain.

Be sure to let us know about all your usual medications. The need to stop them will be discussed well in advance of the procedure.
It is also necessary to inform the anaesthetist of all medications, past medical history and any allergies. Please bring your medicines with you on the day of your procedure so that we can confirm the drugs you are taking. If you suffer from chronic sleep apnoea bring your CPAP machine with you.

Alternatives to colonoscopy

There are other methods available for visualising the large bowel. These are a barium enema and a special CT scan. Whilst these are generally of a lesser inconvenience to the patient in that they do not require sedation, they are purely diagnostic procedures that are often less accurate than a colonoscopy in identifying certain conditions. If a biopsy is required or polyps need to be removed, the patient will then require a colonoscopy to achieve this.

About colonoscopy

A colonoscopy is a flexible fibre-optic scope examination of the colon and rectum which is synonymous with the large bowel. This is a non-surgical procedure and allows visualisation of the internal aspect of the bowel and in particular identification of certain conditions and potential pathology. It also allows procedures to be performed such as biopsies and polyp removal. Whilst the last part of the small bowel can be visualised, it is generally not feasible or necessary to extend the passage of the scope as conditions affecting this part of the bowel are rare. The procedure takes about 30 minutes.
A colonoscopy is a procedure where a flexible scope (colonoscope) is passed through the large intestine (colon and rectum) via the anus. It allows Dr Renaut to see the inside of your bowel on a video screen and to perform procedures such as a biopsies and polyp removal within our Brisbane based practice. The procedure takes about 30 minutes.


There are numerous indications for performing a colonoscopy. The reasons in your particular case will be fully discussed prior to the procedure.

Will I be asleep during the procedure?

A light anaesthetic, sometimes referred to as a ‘twilight sedation’, will be administered for the colonoscopy. Although it is not normally described as a general anaesthetic, you will be heavily sedated and often will not recall the procedure. An anaesthetist will be present on the day and you will have the opportunity to discuss the procedure and any potential complications further with him/her.

What are polyps?

A polyp is an abnormal growth, usually benign (non-cancerous) on the inner lining of the bowel. Larger polyps may turn cancerous with time although this process usually takes several years. Removing polyps in those at risk is therefore an important means of preventing bowel cancer.

What if something abnormal is found?

If possible, it will be dealt with at the time of procedure. Polyps can often be removed, but if it is too large or if a cancer is found, biopsies can be taken.

How will I know what is found at the colonoscopy?

Your surgeon Dr Renaut will speak with you and/or your family members immediately after the colonoscopy. The results of any biopsies will be available a few days later and this information will be passed on to you by phone or Dr Renaut will see you for a follow up as necessary. He will send you home with a formal report which is a copy of the report that he sends to your referring doctor and/or GP. He will also discuss with you the need for a repeat examination.

How accurate is a colonoscopy?

No investigation in medicine is perfect, but a colonoscopy is generally very good at identifying the things that are important. Studies have shown colonoscopies to be more accurate than barium enema, but up to 3% of cancers can be missed. Small polyps can be missed in 6% of cases. Sometimes it is not possible to safely remove a large polyp and under these circumstances a bowel resection at a later date may be necessary. Very rarely it may fail to identify a potential source of bleeding. In about 2% of cases it is not possible to pass the scope through the whole length of the colon. This is usually due to anatomical variation. Under these circumstances it is safer to abandon the procedure and to proceed to a special scan that can examine the part of the colon that has not been seen at colonoscopy.
Currently, CT colonography is still being evaluated. The disadvantage of radiological procedures is that a colonoscopy will still be required if any abnormality is found.

What are the risks?

Colonoscopy is a frequently performed and safe procedure. Complications are uncommon. Most studies report a complication rate of less than 1 in 1000 examinations. The risks tend to be increased when polyps are removed. Important complications include:

  • Perforation of the bowel. This is rare, but will usually be evident soon after the procedure. It may require emergency surgery.
  • Bleeding can occur. This may be from the site of the polyp or biopsy, or related to 
    treatment for haemorrhoids. Very rarely, a blood transfusion may be required and surgery is only necessary in extreme cases.
  • Complications related to sedation are also uncommon.


With colonoscopy, complications are rare and generally minimal. However, it is important to keep in mind that no procedure is completely free of risks or complications.

You may experience some abdominal cramps either at the time of the procedure or afterwards and this is largely due to gaseous distension of the colon which is essential to enable a good view. This usually subsides fairly quickly after the procedure.

Bleeding can occasionally occur and this is more common if biopsies are taken or polyps removed. The bleeding may or may not be noticed by the patient when they next open their bowels. If it is noticed then the amount is usually small and the bleeding usually stops by itself without the need for further intervention. Significant bleeding can occur to the extent that the patient requires readmission to hospital. If this is the case, the patient may require a blood transfusion or a repeat colonoscopy. In rare cases an operation may be required.

A significant complication of colonoscopy is perforation of the bowel. This is rare. It occurs in about 1 in 10,000 colonoscopies but the rate increases if once again polyps are removed. If a perforation does occur it is often identified at the time. Alternatively, the patient may present several hours later with abdominal pain and signs of early peritonitis. This will almost certainly require an operation to repair the perforation which may involve a bowel resection and temporary colostomy but it should be stressed this is a rare occurrence.

Injury to other organs that are in close proximity to the colon, in particular the liver and spleen, can be injured, purely by process of pressure from within the colon. This has on occasion resulted in bleeding from that organ which may require an operation such as splenectomy. This is exceedingly rare.

Because the anaesthetic is light, complications relating to this are rare and are very much related to the existence of other conditions such as heart disease, chest disease, diabetes and obesity. As mentioned your anaesthetist will discuss these issues with you on the day, prior to the procedure.

Further questions

For most patients, the procedure is not nearly as unpleasant as they had imagined or been told by friends or relatives. Please contact our Brisbane rooms if you have any questions. There will be a further opportunity to speak to Dr Renaut prior to the procedure.

Colorectal Polyps - the various types and their management

Post-operative care following a colonoscopy procedure

Your surgeon will speak with you immediately after the procedure. The results of any biopsies taken will be available a few days later and this information will be passed on to you by phone or in a follow up consultation as necessary. You will be sent home with a formal report which is a copy of the report that is sent to your referring doctor and/or G.P.

The following day you should be completely back to normal and ready to resume your day to day activities.

Bowel function returns fairly quickly in particular the passage of flatus. A normal diet can be resumed almost straight away unless there are specific instructions to the contrary. If you do suffer one of the unusual complications such as excessive bleeding or pain or if you feel unwell, for more than a few hours then you should not hesitate to contact your specialist or G.P.

What can I expect after the colonoscopy?

The colon is inflated with air to distend it so that a good view can be obtained. Most of this air is sucked out upon withdrawal of the scope but a small amount of retained gas can cause a bloated feeling and some crampy "wind" pains. This usually passes quickly but may persist for a few hours. You will be able to have a light meal as soon as the sedation has started to wear off. Severe pain is not expected and you need to contact Dr Renaut if this is the case.

Effects of sedation and safety issues

Even though you may feel fine after the procedure, small amounts of sedative will remain in your bloodstream. For this reason, it is vital that you must not drive a car or operate machinery for 24 hours after the procedure. Failure to follow this advice carries the same implications as drink driving and is against the law. You should also not sign any contracts or make important decisions for 24 hours. You should not consume alcohol as the sedative effects will be increased. You should be cautious with simple tasks around the house e.g. using knives etc. You must be taken home from Brisbane Private Hospital by a responsible person and cared for overnight by a responsible adult.

Related Information

Read about Gastroscopy
Read about Colon Cancer
Read about Colorectal Cancer Screening Guidelines
Read about Colonic Polyps
Read about Diverticular Disease
Read about Rectal Cancer