What is a Colonoscopy?

A colonoscopy is a procedure where a flexible telescope (colonoscope) is passed around the large intestine (colon and rectum) via the anus, to the portion of the colon where the small intestine enters. It allows the doctor to see the inside of the bowel on a video screen and to perform procedures such as a biopsy, removal of polyps, marking of polyps (with ink), and treatments for bleeding. The procedure takes 30 to 60 minutes.

How am I prepared?

In order to obtain clear views, 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.

What about my usual medications?

In general, these should all be taken as usual. Exception will include:

  • Warfarin or other blood thinning drugs
  • Aspirin or other anti-inflammatory drugs
  • Insulin or other diabetic tablets
  • Iron supplements
  • Any herbal drugs (you will need to check with the manufacturers as to what these contain).


The need to stop these medications will be discussed with Dr Petersen beforehand.

It is also necessary to inform the anaesthetist of all medications, past medical history, and any allergies.

Will I be awake during the procedure?

An anaesthetist will usually be present and you will have the opportunity to discuss this further with him/her. Although it is not normally described as a general anaesthetic, you will be heavily sedated and often will not recall the procedure.

What if something abnormal is found?

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

What are polyps?

A polyp is an abnormal growth on the inner lining of the bowel. Although they are not usually cancerous, most will grow into cancer with time. Removing polyps is an important means of preventing bowel cancer.

How will I know what is found at the colonoscopy?

The doctor will speak with you and/or your family members immediately after the procedure. A formal report is sent to your general practitioner and copies can easily be sent to any other doctors involved in your care. Usually you will have a follow up consultation one to two weeks after the procedure to confirm the colonoscopy results.

What are the risks?

Colonoscopy is a frequently performed and safe procedure. Complications are uncommon. Most studies report complications is less than 1 in 1000 examinations. Risk is increased when polyps are removed.

Important complications include:

  • Perforation of the bowel – this is usually evident soon after the procedure and 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 and your anaesthetist will monitor you during the procedure.

What can I expect after the procedure?

Because air is inflated into the bowel during the procedure, it is very common to feel bloated and have crampy “wind” pains. This may persist for up to 48 hours.

You will have a light meal as soon as the sedation has started to wear off.

Severe pain is not to be expected and you need to contact Dr Petersen by phoning 3831 0699.

Effects of Sedation/Safety Issues:

Even though you may feel OK after the procedure, small amounts of sedative will remain in your bloodstream. For this reason, you must not drive a car or operate machinery for 12 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 cautions with simple tasks around the house e.g. using knives, etc.

Responsible Person:

You must be taken home and cared for overnight by a responsible person.

How accurate is colonoscopy?

No investigations in medicine are perfect. Studies have shown colonoscopy to be more accurate than barium enema but up to 3% of cancers can be missed. Small polyps can be missed in up to 6% of cases. CT colonography is still being evaluated and radiological procedures have the downside that a colonoscopy will still be required if any abnormality is found.

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 my rooms if you have any questions. There will be a further opportunity to speak to Dr Petersen prior to the procedure.