This information is for patients who are having an examination of the bowel known as a colonoscopy. It explains what is involved, and any significant risks that there may be.
Colonoscopy is an examination which allows visualisation of the lining of the large intestine or colon using a colonoscope, a flexible tube about the thickness of the little finger. Sometimes a sample of the lining of the bowel (a biopsy) is taken for laboratory examination. If polyps (projections of tissue rather like warts) are found, they can be removed during the examination. The procedure takes on average about 25 minutes. Normally you will be able to go home 45 minutes later.
• for this examination to be successful and allow a clear view of the colon, your bowel must be as empty as possible. It is very important to follow the advice given about bowel preparation for colonoscopy.
• if you are taking blood thinning medications (e.g. warfarin or other anticoagulants, clopidogrel or other anti-platelet agents) please inform us. You may continue to take other medications as normal, except iron tablets or stool bulking agents (eg. Fybogel, Movicol, Regulan, Proctofibe) which should be stopped one week before your examination.
• please bring a list of any medications you are currently taking; it is especially important to remember to bring any asthma inhalers or angina sprays with you.
• a nurse will check your details, blood pressure and pulse. If you are allergic to anything (medications, plasters, latex), please tell the nurse. Please let us know about any medication you may be taking or if you are allergic to any medications, plasters etc, latex etc.
• the procedure will be explained again and you will be asked to sign a consent form to confirm that you understand the examination and agree to go ahead with it.
• a small needle will usually be inserted into a vein and a sedative and painkiller given before the examination. This may make you feel more relaxed and sleepy and can affect your memory of the procedure.
• A small device for recording the pulse and breathing will be attached to your finger and you will be given oxygen.
• you are helped to lie in a comfortable position on your left side and then the colonoscope is be passed into your back passage and around the large bowel.
• air is passed into the bowel to expand it so the bowel lining can be seen more clearly. This may give you some discomfort, but it will not last long. Some may come out again as wind. Please do not worry about this, it is quite normal.
• you may feel as if you want to go to the toilet, but as the bowel is empty you do not need to worry about it actually happening. Any remaining fluid in the bowel will be removed by the colonoscope.
• a biopsy may be taken during the examination to be sent to the laboratory for further tests. Similarly, any polyps may be removed during the examination. You cannot feel biopsies or polyps being removed but you can sometimes visualise what is happening.
• you will return to the recovery area to rest for at least 30 minutes. Once recovered you may eat and drink as normal. You may still have a little wind.
• the result of the examination will be available before you go home. Any biopsy results will take longer.
• even though you feel fully awake after having sedation it is important to arrange for somebody to pick you up from the hospital, or if arranging transport home for somebody to be there to look after you. They can then deal with any problems that may arise, despite this being very unlikely.
• it is important that after sedation you do not attempt to drive for 24 hours.
This test is very safe, but very rarely there can be a problem:
• a reaction to the sedative. The sedative can affect your breathing making it more slow and shallow.
• this procedure is the gold standard for detection of colonic polyps and cancers and is better than CT scanning. There remains, however, a small risk of missing small lesions. It is unlikely to miss a cancer.
• when a biopsy is taken or a polyp is removed, there may often be a little bleeding which usually stops by itself. More serious bleeding is very rare.
• perforation, which is a tear in the wall of the colon. This will require a stay in hospital and treatment with antibiotics, and may require surgical repair. This is very rare (less than 1:1000).