Colonoscopy is a procedure used to examine or inspect the bowel and allows for a variety of operations to be carried out through the colonoscope.  These operations may include taking small tissue samples (biopsies) and removal of polyps.  An alternative method of examining the large bowel is barium enema.  Colonoscopy has the advantage over barium enema of allowing tissue samples or biopsies to be taken.

The colonoscope is a long and highly flexible tube about the thickness of your index finger.  It is inserted through the rectum into the intestine to allow inspection of the whole large bowel. As cancer of the large bowel arises from pre-existing polyps (a benign wart-like growth), it is advisable that if any polyps are found they should be removed at the time of examination.  Most polyps can be burnt off (polypectomy) by placing a wire snare around the base and applying an electric current.

How Are You Prepared?

Prior to the colonoscopy you will be provided with a preparation kit containing full instructions.  For a few days before the procedure you will need to follow a low residue diet.  The night before the procedure you will need to take laxatives, and on either that evening or the morning of the procedure, you will need to drink a quantity of salty tasting solution which completely cleanses the colon.

You will be given a sedative through a vein in the arm before the procedure to make you more comfortable

Safety & Risks

For inspection of the bowel alone, complications of colonoscopy are uncommon.  Most surveys report complications in 1 in 1,000 examinations or less.  Complications which can occur include an intolerance of the bowel preparation solution or reaction to sedatives used.  Perforation (making a hole in the bowel) or major bleeding from the bowel is extremely rare but if it occurs, this may require surgery.

When operations such as removal of polyps are carried out at the time of examination, there is a slightly higher risk of perforation or bleeding from the site where the polyp has been removed.

Complications of sedation are uncommon and are usually avoided by administering oxygen during the procedure and monitoring oxygen levels in the blood.  Rarely however, in patients with severe cardiac or chest disease, serious sedation reactions can occur.

A number of rare side effects can occur with any endoscopic procedure.  Death is a remote possibility with any interventional procedure.  If you wish to have full details of rare complications, you should indicate to your doctor before the procedure that you wish for all possible complications to be fully discussed.

Because of the risk of cancer, it is recommended that all polyps found at the time of colonoscopy be removed.  However, it will not be possible to discuss the removal with you at the time of examination as you will be sedated.  Therefore, if you agree to having removal of any polyps found during the procedure, please sign the consent form.  If you have any queries or reservations about this, please inform you doctor.

In the unlikely event of haemorrhage occurring, blood transfusion may be necessary.


The sedative painkiller you are given before the procedure is very effective in reducing any discomfort.  However, it may also affect your memory for some time afterwards.  Even when the sedative appears to have worn off, you may find you are unable to recall details of your discussion with your doctor.  For this reason, a relative or friend should come with you if possible.  If you do not recall discussions following the procedure, you should contact your doctor.

If you have any severe abdominal pain, bleeding from the back passage, fever or other symptoms that cause you concern, you should contact your doctor immediately.


Dr Karihaloo practices from the second floor of the Lake Macquarie Specialist Medical Centre.

Level 2, Suite 1
Lake Macquarie Specialist Medical Centre
6-8 Sydney St, Gateshead NSW 2290

If you have any enquiries or to make an appointment phone (02) 4947 8177 or email