Colonoscopy is a procedure which enables the doctor to see inside your large bowel. Unlike a barium enema, which takes x-ray photographs, a colonoscopy lets the doctor see the surface inside the bowel directly and provides more detail and accuracy than x-rays.

The procedure is performed following extensive preparation of your bowel. The instrument used is a thin flexible tube containing a video camera. If necessary, small tissue samples (biopsies) can be taken during the examination, painlessly, for laboratory analysis. Polyps, wart-like growths that can evolve into bowel cancers, can also be removed using a snare wire. Simple food dyes are sometimes sprayed on the bowel to detect early polyps.

How accurate is a colonoscopy?

Colonoscopy is an important tool for the diagnosis and treatment of many diseases of the large bowel. Colonoscopy is an accurate, although not perfect test. Rarely small early malignancies can be missed. The risk of this is minimised by performing a full colonoscopy to the caecum or terminal ileum, and having a well prepared bowel. The current literature suggests approximately 1-3% (of cancers) are missed. The chance of developing a bowel cancer in the screening interval after a satisfactory colonoscopy is estimated at about 1 in 2000. This risk is composed of missed lesions, aggressive, rapidly growing lesions, and incompletely resected lesions. The following will help ensure the risk is minimized:

  1. Your bowel is very well cleaned.
    • It is important you take the bowel preparation correctly.

  2. A full colonoscopy to the terminal ileum is performed.
    • This is possible in about 98% of patients.

  3. The use of Indigo Carmine Dye.
    • This is sprayed in the bowel and probably improves the detection of flat polyps. Currently this is relatively new technique but in now used in most patients. Indigo Carmine is a harmless food dye.

Virtual Colonoscopy or Barium Enema

Colonoscopy is more accurate in detecting lesions than a barium enema or a "virtual colonoscopy". If a lesion is detected with these techniques a colonoscopy is still necessary. Virtual colonoscopy currently can miss up to 10-30% of significant polyps. No samples can be taken with these techniques.

Virtual colonoscopy is a special type of CT scan. It involves the same bowel preparation as a fiberoscopic colonoscopy and if any lesions are found, you will require a repeat full preparation prior to the colonoscopy procedure. Due to significant air placed in the bowel, 50% of patients find virtual colonoscopy uncomfortable. Virtual colonoscopy is, however, used for patients for whom colonoscopy is considered unsafe or incomplete. Virtual colonoscopy also involves exposure to X-Rays.

Faecal Occult Blood Testing

This is a useful screening test for colorectal cancer in people without symptoms. However, on its own it only detects approximately 30% of bowel cancer. If this test is positive, then you will need a colonoscopy. If you have symptoms of a bowel disorder, then this test is not the appropriate test.

Capsule Endoscopy

This capsule is designed, at this stage, for only looking at the small intestine. Very minimal views are obtained of the colon.

CT scan or MRI scan

This is excellent for detecting pathology within the abdomen predominantly involving the solid organs such as the liver, spleen and pancreas. It is not good for the detection of polyps. It can be useful for the detection of diverticulitis.

Colonoscopy is a very safe procedure for the majority of people. We go to great lengths to try and minimise risks and potential side effects. Below are some of the potential complications which can occur. Minor temporary changes in bowel habit and wind-type symptoms are common immediately after colonoscopy, and if you have any concerns you should contact your doctor or the hospital without delay.

Intolerance to colonic preparation

After taking the colonoscopy preparation, patients occasionally get abdominal cramping, nausea or vomiting. Rarely dizziness and fainting can occur. Very rarely patients can have palpitations or severe imbalance of body salts-electrolytes. In view of this, a responsible adult must be present in your home during the preparation. It is important that the instructions are followed carefully to minimise the risk of this problem.

Reaction to the anaesthetic

Serious reactions are rare. Complications can include: pain in the arm at the injection site, brusing or infection where the cannula is inserted, nausea and vomiting, altered heart rates, dizziness or fainting, allergic reaction, aspiration of vomit from the stomach into the lungs, heart attack, stroke and death (extremely rare).

If you have any questions please ask the anaesthetist prior to the procedure.


This is very rare following a standard colonoscopy and biopsy. The risk is increased if a polyp is removed. This occurs in approximately 1:1000 cases but up to 1-3% if very large flat polyps are removed. If bleeding occurs, this may require hospitalisation. Rarely a blood transfusion and operation is required to control the bleeding.

Patients on anti-platelet/blood-thinning medications need to consult their doctor prior to having their colonoscopy. If these are continued, then polyps may not be able to be removed during the procedure.


With a standard colonoscopy in a healthy bowel, without removal of polyps, the risks of perforation are approximately 1:10,000 procedures. The risks can be higher if your bowel is diseased (e.g severe diverticulosis).

If there is a perforation, this can present with severe pain following the procedure. This life threatening complication will require a prolonged hospital stay and usually an operation with possibly a colostomy bag for two months.

Acute diverticulitis can be exacerbated

A colonoscopy should not be performed within 4 weeks after an attack of diverticulitis.

Missing polyps and cancers

Colonoscopy and polypectomy reduces the risk of cancer but there are still a small percentage of procedures where a significant lesion is not detected (see section on "what is a colonoscopy").

Damage to other organs

Very rarely, damage can occur to the other organs during colonoscopy such as damage to the spleen. This is a very, very rare complication.


These are samples taken from the bowel to look for any inflammation or any other significant pathology.


Colonoscopy's great use is in the detection of colon cancer and colon polyps. Prior to the introduction of colonoscopies, removal of polyps required a major open abdominal operation, and required a 2 week stay in hospital and a longer convalescence. Most polyps now can be removed easily and safely without surgery.

Periodic colonoscopy is a very useful procedure for the follow up of patients with previous polyps or colon cancer. Regular colonoscopy can reduce the risk of developing bowel cancer by up to 90%. How frequent it is performed depends on your family history and previous history of significant polyps. Generally, this is within 3-5 years.

Polyps are abnormal growths of tissue on the bowel lining which vary in size. Most polyps can be removed at the time of the procedure. Polyps are usually removed because they may cause bleeding or can become a cancer. Although the majority of polyps are benign (not cancerous) a small percentage may contain an area of cancer or develop into a cancer if not removed.

Removal of a polyp often involves passing a snare (wire loop) through the colonoscope over the polyp and then cutting through the stem using an electrical current. The risks involved are small and far less risky than an operation or leaving the polyp to perhaps form a cancer. These risks range from severe bleeding (1% of large polyps), to perforating the colon, (less than 1 in 1 000 for polypectomy procedures). These risks are very rare but may require urgent treatment or even an operation. The risk of their occurrence is far outweighed by the advantages of removing the polyp.

Indigo Carime Dye Staining (if used)

This may be performed at the time of colonoscopy. It is harmless blue food dye that is sprayed onto the lining of the bowel. This can improve the detection of early and flat colonic polyps by up to 1 00%. You may notice blue/green discolouration of your bowel motions after this procedure.


If a bleeding point is identified at colonoscopy, this may require therapy with an injection, the use of diathermy (gold probe), an Argon plasma coagulator or metal clips to stop the bleeding.

Saline Injection

If a large, flat polyp is detected, then a cushion of salty water is injected into the base of he polyp to lift this up. This reduces the risk of damage or perforation to the underlying bowel when the polyp is removed.


If a polyp is detected with a large stalk, a special suture may be placed at the bottom of the stalk (endoloop) or a small metal clip (endoclip), to reduce the risk of bleeding after the polyp is removed.


If a polyp is detected with some worrying features, then a black ink marker is placed around the polyp site. This permanently marks the site so it can always be checked again in the future, or if the area of bowel requires surgery, then the surgeon will immediately identify the site where the polyp was removed.


If a narrowing within the bowel is identified, this occasionally will require stretching (Dilatation) with a special balloon that is passed through the colonoscope into this stricture and then inflated to stretch the narrowed area.

Prior to colonoscopy, patients with any health issues, or who take regular medications, are assessed by a nurse, or in complicated cases by Dr Holt. This is to help to minimise any risks and assist with understanding of the preparation process. Nurse assessments for open access patients occur through our rooms on Wednesday afternoons in Limestone street, or via St Andrew's hospital, if that is where your referral is directed by your general practitioner.


Most medications should be continued, as per normal, during your study. This is especially true for all blood pressure and heart medications. Take these right up to and including the day of the procedure (take with a small amount of water).
Those medications which may need to be altered are listed below:
You will be instructed by the nurse in regard to these at your pre-procedure assessment. If you are unsure, do not hesitate to contact us.

If you are a diabetic, special instructions will be given to you. Because ther will be periods of fasting during your preparation some medications are stopped prior to the procedure to avoid hypoglycaemia. This is especially important if you use insulin. Please notify our staff on booking if you are an insulin-dependent diabetic so we can arrange nurse assessment, and an early morning appointment.

Iron tablets
These should be ceased seven days before the procedure.

Aspirin or fish oil
These can be continued unless advised otherwise. Biopsies and polypectomies can be performed safely on aspirin.

Warfarin and other anticoagulants (blood thinners)
Therapy should be individualised by discussing this at the time of your pre-procedure consultation. If you continue with strong anticagulants up to the time of the procedure, then it is still safe to perform a colonoscopy, however polyps cannot be removed during the procedure due to the risk of bleeding.

Antiplatelet / Anticoagulant Agents include:

  • lscover/Plavix (Ciopidogrel)
  • Warfarin
  • Xeralto
  • Eloquis
  • Clexane
  • Aggrostot

Because these medications have a strong anti-platelet/anti-coagulant effect, they may need to be ceased prior to the colonoscopy. The amount of time these need to be ceased varies considerable with each medication. How to take these medications will be discussed at your pre-procedural appointment. Your cardiologist may need to be contacted in some cases. If you do cease these medications, aspirin may be substituted (if appropriate) . If the above medications are not ceased, then significant polyps will not be able to be removed at the time of the procedure.

Heart Problems

We will need to give you antibiotics during the colonoscopy for the following heart conditions:

  • Prosthetic heart valves/severe valve disease;
  • History of endocarditis;
  • Surgically constructed shunts.

Please inform us if you have a pacemaker. If you have an implanted defibrillator you should have your procedure in a major hospital. It may also be necessary to consult with your Cardiologist.

Recent Tests

You should not have a colonoscopy performed if you have had a barium enema or a barium meal in the last seven days. Please let us know if you have had these tests performed recently.

Colorectal cancer affects approximately 1 in 20 Australians. You can reduce, significantly, the risks of bowel cancer by:

1. Improving Diet
Reduce dietary fat. Increase fruit and vegetables, in particular, cruciferous vegetables (bok choy, broccoli, brussel sprouts, cabbage, and cauliflower). You should reduce the amounts of beer consumption, although moderate wine consumption may reduce your risks of bowel cancer. If you wish to take a supplement, then consider calcium, folic acid and possibly selenium vitamins which may reduce the risk of bowel cancer by 30-40%.

2. Increasing physical activity and stop smoking.

3. Regular faecal occult blood testing.

4. Regular screening colonoscopy with removal of polyps will reduce your risks of bowel cancer by 80-90%. The frequency of this depends on your family history and whether you have had polyps in the past.

You should have a colonoscopy performed if you develop symptoms of bleeding from the bowel, anaemia, change in bowel habit, especially a recent one; or recent onset of abdominal pain.

For a successful colonoscopy it is important that the bowels are thoroughly cleansed so that the lining is clearly seen. Poor preparation may result in the doctor being unable to examine the bowel properly and a repeat procedure may well be required.

THREE (3) days prior to a colonoscopy please commence a low fibre diet.

This diet reduces the amount of fibre in your colon to assist in achieving a thoroughly clean bowel. Please eat only what is available in the diet below. If you find that you do become constipated with the low fibre diet then take half a teaspoon of Epsom Salts in warm water, Coloxyl or Agarol (these laxatives do not contain fibre).

Bread and Cereal


White bread, refined breakfast cereals (Cornflakes, Special K, Rice Bubbles), plain cakes and biscuits made with white flour, white pasta or white rice.


Wholemeal, brown and rye breads, wholegrain cereals, cakes and biscuits containing nuts, dried fruits, wholemeal flour and oatmeal. Avoid wholemeal pasta and rice.

Fruit and Vegetables


Only boiled or mashed potatoes, pumpkin, carrot, marrow, squash, asparagus tips, strained fruit Juice, ripe bananas, stewed apples, pears and pawpaw. (NB Skins and seeds of these fruits and vegetables should not be eaten).


All other fruit and vegetables including salad vegetables.

Meat Group


Lean tender beef, veal, lamb, pork, poultry, fish and eggs.


Fatty and fried meats, highly seasoned meats and stews.



Tea, coffee, water, plain milk drinks, soft drinks, soya milk, strained fruit juices. Alcohol is allowed if desired.


Unstrained fruit juices and flavoured milk shakes.



Jellies, sugar, honey, custard and yoghurt.


Pies, quiches, pastry foods, jams, marmalade, peanut paste, dried fruit and nuts.

A good preparation greatly improves the accuracy of your test. Please continue your low fibre diet up until your procedure as directed. You will be supplied with written instructions for the preparation diet as well as the bowel preparation procedure itself. Ensure you follow this closely as residual dietary fibre can severely compromise the accuracy of the test. Occasionally, some people may require additional prep solution on the morning of the test. Notify hospital staff early if your preparation is not free of particulate material. If you have previously had problems with inadequate cleaning of the bowel please notify the nurse at your pre-procedural assessment.

Results Expected After Taking Bowel Preparation

You should have a relative or friend stay with you whilst taking your bowel preparation. Please inspect the toilet bowl to determine if your bowel motion has a clear yellow appearance. It should be free of any particle matter, although a small quantity of white fleck is acceptable. If you are unsure of the results, please call the Gastroenterologist's rooms for assistance. Occasionally, yellowish bile stained fluid will be noticeable the next morning on the day of your procedure.

What to Expect

The preparation produces watery diarrhoea over a short period. Therefore it is normal to feel lethargic and you will may feel chilled, particularly in winter after drinking the fluid. Drink hot clear fluids and wear warm clothing.

You may also experience some tenderness over the anal region from the frequent diarrhoea. Application of Lanolin cream or Vaseline to the anal region before drinking the prep will help to minimise discomfort. Patients with haemorrhoids may experience discomfort at the anus and therefore should use haemorrhoidal cream. Following preparation a warm bath may assist in soothing the anal discomfort. You will often feel a sense of bloating. Walking and the application of hot packs will usually ease this feeling. Usually the preparation is well tolerated; however you may find some problems.


This may occur for a number of reasons but often because the fluid is not passing from the stomach as quickly as expected. If you experience vomiting, stop drinking the fluid for 30 minutes and have a hot beverage. Then restart drinking. It is important you try to continue as the procedure can only be performed if your bowel is totally clean. A clean bowel can only be achieved by drinking the preparation. It is better to take longer to drink the preparation and not vomit than to try and keep to the time shedule and risk having a poor preparation. If despite everything vomiting persists, stop the prep and notify the doctor on call or a major Accident and Emergency Centre.


A degree of bloating is usual, however if you have experienced significant pain from the distension stop the preparation. If the bloating settles, then start the prep again. If pain and bloating persists or is severe, do not drink any more of the solution and contact the doctor as you may require an injection or even and x-ray, particularly if you have not had a bowel motion.

Failure to Have a Bowel Motion

Patients differ in timing between drinking the prep and when the diarrhoea commences. If you have followed the directions and consumed half the preparation with no results, stop the prep for 30 minutes and have a hot clear (eg black/green tea) beverage. Some people take a lot longer to pass the prep than others. However if you are not experiencing any pain, and bloating is minimal, then continue. Once the diarrhoea has commenced continue drinking the preparation.


This can occur after taking the bowel preparation. Be sure to be in a comfortable position when taking the bowel preparation and close to toilet amenities. Rarely fainting may occur.

Severe Pain and Vomiting

This is very unusual. If you have stopped the prep and the symptoms continue or you fail to improve it is wise to contact the doctor or a major Accident and Emergency Centre for advice as you may have an underlying condition that is causing the problem.

You will normally stay in the Recovery area until you have recovered and then you will be asked to go to the second stage recovery where you ill be seated and have a drink and light refreshments prior to being discharged. You are required to remain in the Clinical area until you are fully recovered. The Doctor will discuss the findings of the test with you before discharge and what type of follow-up treatment /appointments are required, if any. A report will be sent to your referring doctor as well as copies of any pathology results. A normal diet may be resumed immediately upon returning horne.

Following the procedure you can experience:

Bloating and Cramping

This normally settles within a few hours but if not then a medication such as Colofac or peppermint tea can help.


This can occasionally persist for a few days following the procedure. This normally settles within 24 hours and it is unusual to be longer than this. Occasionally, however, some patients get constipation for a few days following the procedure.

Haemorrhoidal Bleeding

This can occur following the procedure, and especially the preparation, due to flare-up of the haemorrhoids.


If you have severe symptoms, you would need to contact your GP, Dr Holt or present to a major Accident and Emergency Department of a hospital to be assessed.

You may notice after your procedure the blue dye that was used will show up in your bowel motions, this will settle within 24 hours.

After the Anaesthetic

The anaesthetic you are given before the procedure is very effective in reducing any discomfort. However, it may also affect your memory for some hours afterwards. Even when the sedative appears to have worn off, you may find you are unable to recall details of your discussion with the doctor. Arrange a follow-up appointment with your referring doctor or gastroenterologist if you are unclear as to the findings.

Due to the anaesthetic you have had, you are legally under the influence of a mind-altering drug. You must not drive a vehicle, operate heavy machinery or sign legal documents or place yourself in any hazardous situations for at least 24 hours after the procedure.

You should not take public transport or use a taxi to go home unless you have a responsible adult with you. It Is Important that a responsible adult accompanies you home and Is able to look after you for 12 hours after the procedure.