Colonoscopy

What is colonoscopy?

A colonoscopy (scope) is the examination of the lower gastrointestinal tract to diagnose, and in some cases, treat changes. This procedure involves passing a colonoscope — a long, thin flexible tube with a 'video camera' at the tip — through the anus into the colon (large intestine, large bowel). It allows the doctor to inspect the colon and to perform specialised procedures such as taking biopsies for pathology and removal of polyps (abnormal growths which sometimes develop into cancer).

A colonoscopy is generally recommended if you have received a positive screening result from your Faecal Occult Blood Test (FOBT) through the National Bowel Cancer Screening Program.

Why have a colonoscopy?

Colonoscopy can detect polyps, inflamed tissues and cancers, such as colorectal cancer. It can help doctors diagnose unexplained changes in bowel habits, unexplained tiredness, abdominal pain, bleeding from the bowel and weight loss. In some individuals with a family history of colorectal cancer, it may be an appropriate test and may even help to prevent colon cancer through removing abnormalities before cancer can develop.

How do I prepare for colonoscopy?

For a colonoscopy to be successful, it is essential to empty the bowel thoroughly of all waste material. This is done by taking a bowel preparation that will cause diarrhoea (see below). If the colon is not clean, the doctor may not be able to examine the bowel lining properly, and you may have to return for another procedure.

A complete bowel preparation consists of:

1. Modifying your diet

   This usually involves you being asked to have a fibre free diet for several days leading up to your colonoscopy. You may be asked to avoid food that contains fibre, nuts and seeds. This improves the likelihood of a successful bowel preparation.
   

2. Taking a bowel preparation

   There are several bowel preparations (laxatives that cause diarrhoea and empty the colon). Depending on your medical condition, your doctor will recommend the right one for you.

   A complete bowel preparation is essential for an accurate and safe colonoscopy. Please follow the bowel preparation instructions exactly. If you have any questions regarding the making up or taking of your preparation, contact the number provided by your specialist for assistance.

3. Increasing your fluid intake

   Specific instructions will be given to you by your doctor.

You should inform the doctor of all medical conditions and any medications, vitamins or supplements taken regularly. Iron supplements are generally stopped a week before the procedure.

How is colonoscopy performed?

Sedation

For the procedure sedation is usually given. You may be vaguely aware of what is going on in the room, but generally you will have little recollection of the procedure. The doctor and medical staff will monitor your breathing, pulse and blood pressure during the procedure and will make you comfortable.

A colonoscopy itself usually takes between 20 and 45 minutes, however you will be at the hospital/clinic for at least a few hours on the day of your procedure.

Examination of the bowel

In the procedure room, the doctor will pass the scope through the anus and into the colon. A small camera in the end of the scope transmits a video image to a monitor, allowing the doctor to closely examine the colon lining.

Once the scope has reached the point where the small intestine joins the colon, it is withdrawn carefully and slowly so the lining of the colon can be examined thoroughly, again. You can see why it is very important for the colon to be clean prior to your procedure as this enables the colon wall can be examined properly.

Removal of polyps and biopsy

A polyp is a growth involving the lining of the bowel wall. They are common and are usually harmless, but a small proportion of them will develop into cancer. Removing them is an effective way of preventing cancer.

Small tissue samples (biopsies) of the colon may also be taken for examination under a microscope for signs of abnormalities.

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

You may feel a little bloated due to the air that is used to inflate the colon to allow adequate inspection of the lining. It generally passes within an hour or two.

Rarely you may pass a small amount of blood. This is often due to the tissue samples that have been taken and should settle.

Post-sedation considerations

It is very important that you do not drive a car, travel on public transport alone, operate machinery, sign legal documents or drink alcohol on the day of the colonoscopy. This is because of the sedation given during the procedure.

If you have had sedation, you will not legally be able to drive home. Your hospital discharge instructions will provide you with information on how long before you can drive again and if someone needs to stay with you after the procedure.

Full recovery is expected by the next day. It is important to read your discharge instructions carefully.

Are there any risks or side effects?

Although complications can occur, they are rare when the procedure is performed by doctors who are specially trained in colonoscopy.

In Australia, very few people experience serious side effects from colonoscopy and polypectomy (polyp removal).

The chance of complications depends on the exact procedure that is being performed and other factors including your general health.

Very rarely (one in 1,000 cases), the bowel lining may be torn. Your Specialist will decide what treatment is best for you to repair the tear, sometimes this involves an admission to hospital and an operation.

Occasionally, people may react to the bowel preparation medication and experience headaches or vomiting.

Reactions to the medications used for sedation are also possible, but again rare.

In a few cases, if the colonoscopy is not successfully completed it may need to be repeated.

If you have any of the following symptoms up to 14 days after the colonoscopy you should contact the hospital or your doctor's rooms immediately:

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

How accurate is a colonoscopy?

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

A colonoscopy can miss small polyps in the bowel in 2 to 8 per cent of cases. For bigger abnormalities such as cancer, the chance is much less, but still present.

If you have had a colonoscopy and abnormalities were found, your doctor may recommend repeating the procedure to monitor your colon every few years, depending on your individual circumstances and family history.

If you had no abnormalities, you are clear to wait for four to five years before resuming regular FOBT screening every two years, preferably through the National Bowel Cancer Screening Program (NBCSP) if you are eligible (aged 50–74 years).

The FOBT (Faecal Occult Blood Test) detects traces of blood in your poo that may be an early sign of bowel cancer or other abnormalities in the lining of your colon. FOBT kits are also available from some pharmacies, pathology laboratories or online, if you are not eligible for the NBCSP.

Sterilisation of the instruments

In accordance with the stringent guidelines published by the Gastroenterological Society of Australia (GESA) for infection control, the colonoscope and all instruments used during your procedure should be thoroughly cleaned or disposed of as outlined in the guidelines.

Who can I contact if I have any questions?

If you have any questions or need advice, please speak to your GP or your Specialist before the procedure.

Important points

• Colonoscopy is a procedure used to see inside the colon and rectum.
• Prior to the procedure, follow any required dietary changes and use a bowel preparation kit to empty all solids from the colon. Read and follow the instructions carefully.
  
• During colonoscopy sedation is generally used to keep you comfortable.
• The doctor can remove polyps and biopsy abnormal looking colon wall if found during the colonoscopy.
• Driving is not permitted for 24 hours after a colonoscopy to allow the sedative time to wear off, so you will need to arrange for someone to drive you home.
• It is advisable to have someone stay with you overnight after your colonoscopy, to ensure you are ok.

More information

You can find patient resources including this colonoscopy fact sheet from the Gastroenterological Society of Australia (GESA).