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MercyAscot Endoscopy

Private Service, Gastroenterology & Hepatology (Liver), General Surgery, Respiratory


Colonoscopy is a visual examination of the lining of your large bowel (colon) using a colonoscope (long, flexible tube with a small camera on the end). The colonoscope is passed into your rectum (bottom) and then moved slowly along the entire colon. A small video camera sends an image onto a video screen and photos can be taken. 

The doctor can look for any abnormalities and if necessary small tissue samples (biopsies) can be taken painlessly through the colonoscope using tiny biopsy forceps. The tissue samples are sent to the laboratory for examination under a microscope. Colonoscopy may also be used to remove polyps in the colon. Polyps (abnormal growths of tissue) can be removed with diathermy forceps or for large polyps a diathermy snare. This is done by passing a wire loop, like a lasso, over the polyp. The polyp is cut from the bowel lining using an electrical current (diathermy) which seals the tissue and stops bleeding. This current cannot be felt and causes no pain. The colonoscopy procedure can take between 10 and 60 minutes.

A colonoscopy may be suggested by your doctor if you have:

  • some alteration in bowel habit e.g. diarrhoea, constipation
  • unseen blood in the stool (occult)
  • bleeding from the bowel
  • anaemia
  • abdominal pain
  • family history of bowel cancer
  • abnormal barium x-ray
  • previous treatment for polyps, bowel cancer, colitis (inflammation of the colon).

  Risks + Complications from a simple colonoscopy examination are rare but can occur. They include:

  • perforation (tearing) of the bowel wall by the colonoscope can cause leakage into the abdomen especially after endoscopic therapies such as biopsies, polypectomy, dilatations
  • bleeding may occur from the site of the biopsy or polyp removal 
  • allergic reaction to the sedative
  • a polyp or lesion can be missed.

If you would like further clarification of these risks and  complications please discuss them with your specialist or nurse.

What to expect

It is important that the bowel is completely empty of faecal material for the procedure to be thorough and safe.  If it is not entirely clean certain areas may be obscured. The preparation for a colonoscopy procedure will involve modifications to your diet. There are more specific instructions about the preparation including a liquid diet for 1 to 2 days and a bowel laxative prior to the procedure. This means drinking oral laxative medication (to make you go to the toilet more) to empty the bowel. All the instructions are given in a written patient information brochure and support is available through the Endoscopy Unit. 

In addition, it is important to inform the Endoscopy Unit prior to your procedure if you have any of the following:

  • an allergy or bad reaction to medicines or anaesthetics
  • take medication to thin your blood including warfarin, aspirin or arthritis medication
  • prolonged bleeding/clotting disorders or excessive bleeding
  • diabetes
  • heart and lung problems including artificial heart valves
  • artificial hip or knee joint replacements
  • if you are pregnant or breast-feeding.

On admission into the Endoscopy Unit your medical history is recorded by a nurse and further information given in the form of a patient video and written material. A consent form is discussed and signed indicating that you understand the procedure,  the risks and complications involved and consent to have the procedure performed.

In the examination room you will be given medication (a sedative and a pain medication) to make you go into a light sleep. This will be given by a small injection into a vein in your arm or hand. The colonoscopy can take 10 to 60 minutes and you will be supported by two nurses. If required it may be necessary for the nurse to hold your hands and legs ensuring your safety. At all times your privacy and dignity will be respected. Your heart rate and oxygen levels will be monitored during the procedure. The endoscope is gently inserted into the bowel which is inflated with air to obtain a good view. The air may cause wind-like cramps but will pass. Sometimes you may be asked to roll onto your back or side or the nurse may press on your abdomen (abdominal pressure) to help the doctor guide the colonoscope. 

You will spend some time in the endoscopy recovery room after the procedure (probably 1 to 2 hours) to sleep off the sedative and to allow staff to monitor you (take your blood pressure and pulse recordings, etc). Because you have been sedated intravenously (given medication to make you sleep) you should not drive a car, operate machinery or make any important decisions for 12 hours as the sedation impairs your reflexes and judgement. Therefore you will need to arrange for someone else to drive you home. It is recommended to have an adult with you at home afterwards.

If biopsies are taken for examination, your GP and specialist will be sent the results within 5 to 7 working days. A  medical typed report of the procedure will be sent to your GP and specialist. Follow-up information and recommendations will be given by the specialist prior to discharge from the Endoscopy Unit.

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This page was last updated at 2:54PM on October 12, 2021.