Description of procedure
Colonoscopy is an examination of the entire large bowel (colon). It is performed by inserting a flexible camera/telescope through the bottom into the bowel. The endoscopist is then able to manoeuvre the camera around the entire large bowel. This allows the endoscopist to see any abnormality within the colon. Biopsies can be taken to help identify any abnormality. Polyps (benign growths which if left unchecked can grow into cancer over several years) can be removed. Colonoscopy is the gold standard for examining the lower bowel.
Colonoscopy is performed in an endoscopy unit. You will be asked to lie on your left hand side whilst the procedure is performed. You may be asked to change position at the request of the endoscopist but this will be explained at the time. There will be doctors and nurses present during the procedure who will be able to explain to you exactly what is happening.
Indications for colonoscopy
Colonoscopy is performed if there is any reason to consider that there might be an abnormality within the colon. The usual symptoms for which this applies would be a change in bowel habit, rectal bleeding or abdominal pain. Colonoscopy is also performed in individuals without symptoms if there is a strong family history of bowel cancer. Patients with inflammatory bowel disease often require colonoscopy to assess their disease and as part of a cancer surveillance programme.
Will it hurt?
Colonoscopy may be uncomfortable whilst the camera is negotiated around the bends in the large bowel. This often causes a temporary cramping discomfort. Air is used to inflate the bowel to allow good visualisation and this may cause an uncomfortable sensation of distension. With sedation (see below) most patients tolerate colonoscopy without problem. It is, however, sometimes best avoided in very elderly patients. Colnoscopy usually takes approximately 30-40 minutes.
Almost all patients undergoing colonoscopy have sedation. They are given both an injection to act as a pain killer and a second injection to help them relax. This is not a general anaesthetic but the patient may be drowsy and may not remember things clearly. After sedation you will require a period of recovery in the hospital of usually approximately one hour. You will need someone to escort you home and you should not drive, operate heavy machinery or drink for the next 24 hours.
Preparation is required for colonoscopy. Two days before the procedure you must adopt a low residue (low fibre) diet. From lunchtime on the day before the procedure the patient must adopt a liquid only diet. On the afternoon before the procedure you are required to take strong laxatives to empty the bowel so that it can be examined properly. This requires having easy access to a toilet and so it is usually recommended to take both the day of the procedure and the afternoon before off work. You will be provided will all the information required regarding the bowel preparation in plenty of time before the procedure.
Colonoscopy is a safe procedure. A common side effect is abdominal bloating which can last for a few hours after procedure. You may also feel a little out of sorts for the rest of the day due to the sedation.
There is also a very low risk (less then 1:1000) of causing internal bleeding (haemorrhage) or a tear in the bowel (perforation). These risks are extremely low but in theory if a perforation were to occur surgery might be required to repair it and therefore it is standard practice throughout the UK
to inform patients of this risk.
If there is a large polyp which needs to be removed then these risks do rise. However the endoscopist would usually discuss this with the patient before undertaking the procedure.