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You have been advised to have a colonoscopy to help find the cause of your symptoms. This advice sheet has been prepared from talking to patients who have had the test. It may not answer all your questions so if you have any worries please donít hesitate to ask. The staff who are doing the test will be available to answer any queries. Not every hospital does things in the exactly the same way.

What is a Colonoscopy?

Colonoscopy is a test which allows the doctor to look directly at the lining of the large bowel (the colon). In order to do the test a colonoscope is carefully passed through the anus into the large bowel. The colonoscope is a long flexible tube, about the thickness of your index finger, with a bright light at the end. Looking down the tube, the doctor gets a clear view of the lining of the bowel and can check whether or not any disease is present. Sometimes the doctor takes a biopsy Ė a sample of the lining for examination in the laboratory. A small piece of tissue is removed painlessly through the colonoscope, using ting forceps.

It is also possible to remove polyps during the colonoscopy. Polyps are abnormal projections of tissue, rather like warts, which the doctor will want to examine in more detail.

What should you expect?

Before the test

To allow a clear view, the colon must be completely empty of waste material. If it is not, certain areas may be obscured and the test may have to be repeated. The hospital will give you detailed instructions about clearing the colon. It is important to take all of the laxative prescribed and also considerably increase your intake of clear fluids on the day before the examination, which will help clean the bowel. When you come to the department, a doctor will explain the test to you and will usually ask you to sign a consent form. This is to ensure that you understand the test and its implications. Please tell the doctor or nurse if you have had any allergies or bad reactions to drugs or other tests. They will also want to know about any previous endoscopy you may have had, or of any other medical conditions which you may suffer from and any medication which you may be taking. If you have any worries or questions at this stage donít be afraid to ask. The staff will want you to be as relaxed as possible for the test and will not mind answering your queries.

You will be asked to take off your trousers or skirt and to put on a hospital gown. You may also be asked to remove any jewelery or metal objects in case a special piece of equipment, called a diathermy unit, is used.

During the test

In the examination room you will be made comfortable on a couch, resting on your left side, with your knees slightly bent. A nurse will stay with you throughout the test. The doctor may give you a sedative injection to make you sleepy and relaxed. The nurse will probably attach a small device to your finger or thumb, in order to record your pulse rate and monitor your general condition during the examination. When the tube has been gently inserted through the anus into the large bowel, air will be passed through it to distend the colon to give a clearer view of the lining. This may give you some wind-like pains but they will not last long. You may get the sensation of wanting to go to the toilet, but as the bowel is empty, there is no danger of this happening. You may pass some wind but, although this is embarrassing, remember the staff do understand what is causing it. It usually takes up to thirty minutes for the colon to be examined, but the test sometimes lasts longer. X-ray equipment may also be used. When the examination is finished, the tube is removed quickly and easily.

After the test
You will be left to rest in the unit for at least thirty minutes. You may feel a little bloated with wind pains but these usually settle quite quickly.

Going Home
If you are going home after the test it is essential that someone comes to pick you up. Once home, it is important to rest quietly for the remainder of the day. Sedation lasts longer than you think, so you should not:

  • Drive a car
  • Operate machinery
  • Drink alcohol

The effects of the test and injection should have worn off by the next day when patients are able to resume normal activities.

When do I know the result?
In many cases the doctor will be able to tell you the results of the test as soon as you are awake. However, if a sample (biopsy) has been taken or polyps have been removed for examination, the results may take several days.

It is a good idea to have someone with you when you speak to the doctor after the test. Because of the sedation, many people find they forget everything that has been said to them. Details of the results and any necessary treatment should be discussed with your general practitioner or hospital specialist Ė whoever recommended you to have the test.

Further general information Your doctors and specialist nurses are in an ideal position to give you relevant information on your disease and treatment as they know your individual circumstances. Cancerbackup has a help line (0808 800 1234) and a prize winning video available in English, Italian, Urdu, Bengali, Gujarati & Hindi explaining Radiotherapy & Chemotherapy. has over 500 pages describing cancer, its management, practical tips and tool which patients, their carers and their doctors have found helpful during the cancer journey.

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