Colonoscopy is the examination of the large bowel using a flexible tube containing a light and viewing fibres. The tube is about the size of an adult size middle finger. The tube is gently guided through the bowel allowing inspection of the inner wall of the bowel.

Pre-operative Instructions

Prior to the examination the doctor will prescribe a special low fibre diet and some medication to completely empty the bowel. This allows an adequate examination of the bowel wall. You should follow the instructions given to you to enable the examination to be as successful as possible.

You will be asked to take some ‘Dulcolax’ tablets prior to the procedure, and to commence your bowel preparation the afternoon before the procedure. The preparation will give you diarrhea and may make you feel nauseated.


An Intravenous needle will be inserted in your hand or arm and several medications will be given to help you relax and dull any pain you may feel. You will begin the procedure lying on your left side; however, it may be necessary to move several times during the procedure to enable the instrument to be guided through your bowel.

The examination usually takes less than one hour from the time you enter the examination room. The procedure is usually not painful but you may feel some discomfort like wind pains. This can be helped by taking slow deep breaths to help your body relax.

A polyp (a small growth in the bowel) may be found and the decision will be made to remove it or take samples. You are not going to feel this. The polyp is removed by passing a small wire around the lesion and excising it using an electric current.


There are some risks/complications which include:

  • Damage to the bowel causing leakage of bowel contents into the abdomen. Further surgery may be needed to repair the tear or puncture (perforation). This may require a longer stay in the hospital.
  • Abdominal pain following removal of polyp(s) and other symptoms (rapid pulse, fever) within 12 hours to 5 days after the procedure. Symptoms usually clear within 48 hours.
  • Damage to large blood vessels or oozing from the site where the polyp was removed, causing bleeding from the bowel. Rarely, further surgery and a blood transfusion may be necessary.
  • Abdominal bloating caused by air left in the large bowel following the procedure. There may be mild to severe pain, which usually settles with walking, and moving around to get rid of trapped air.
  • Very rarely heart and lung problems such as an increased heart rate. Emergency treatment may be necessary.
  • Bacteremia (infection in the blood). This may cause infection and possibly fever and chills and is more common for those with ill health.
  • Mild pain and discomfort in the abdomen for one or two days after the procedure.
  • Heart and lung problems following the injection of sedative into the vein. The person who has ill health is at greater risk.
  • Death is a complication from colonoscopy but is extremely unlikely but possible.