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What is a colonoscopy?

A colonoscopy is a test to look at the lining of the large bowel or colon. Colonoscopy is done by a colonoscopy specialist. It should take between 30 and 45 minutes, although the whole appointment may take around two hours.
During this test, the specialist uses a thin flexible tube (a colonoscope) with a tiny camera on the end to look inside your bowel. The tube is about the width of your little finger and is passed through the anus (back passage) into the bowel.

Why do I need a colonoscopy?

This test looks at the large bowel to make sure there are no diseases in your large bowel that could be causing you to be unwell, for example inflammation of the bowel called colitis. We look for polyps in the bowel, as we know that removing these polyps when they are small, reduces your risk of developing bowel cancer in the future. We can also detect bowel cancers with this test.
The doctor doing the test will normally be able to give you preliminary results on the day.

Is the test painful?

Having the test can make you feel uncomfortable, and to help with this, you can have “gas and air” (Entonox) which is a quick acting form of pain relief and is out of your system very quickly.
You will be able to drive home straight after the test if you have this form of pain killer. However, some people need something stronger, and in this situation, you can be given sedation. This can make you feel a little bit sleepy. The sedative is usually given by injection into your arm and may make you drowsy. You may be less alert than usual for up to 24 hours.

So, if you have the sedative, it is important that you:

  • don’t drive home - have someone pick you up from the hospital
  • don’t drink alcohol for 24 hours
  • don’t operate machinery

Should I take all my normal medication before the test?

You should have had a chance to discuss any medications you are taking with one of our nurses or doctors before your procedure. If you are taking anti- platelet medication or anticoagulant medication to prevent the formation of blood clots (such as aspirin or clopidogrel, warfarin, rivaroxiban or dabigatran); sedatives, chronic pain medication, or medications for diabetes, please let the doctor or nurse know in good time before the date of your procedure. You should continue to take all of your medications as normal, unless you have been told otherwise by the doctor or endoscopy nurse.

Are there any alternatives to a colonoscopy?

This test is the best test to look at the lining of your bowel. However, please note that occasionally the colonscopy may need to be abandoned or may be incomplete. This can happen if you find the procedure too uncomfortable or if the bowel preparation did not empty your bowel completely. In this case, the test may need to be repeated or we may suggest an alternative procedure. The most common test to request is a CT scan to look specifically at the large bowel. This is called a CT pneumocolon.

Are there any risks with a colonoscopy?

A colonoscopy is usually safe but in rare cases it can cause harm to the bowel. About 1 person in every 400 has bleeding after their colonoscopy but it is usually easy to stop. Rarely, the bleeding is more difficult to stop and means that the person needs to be admitted to hospital.

This happens to about 1 in every 2000 people having a colonoscopy. Even more rarely, colonoscopy can cause a small tear in the bowel. This happens to about 1 in every 2500 people having a colonoscopy.
If you have bleeding that is difficult to stop or a tear in your bowel, you will be admitted to hospital straightaway. Some people will need surgery to repair their bowel.

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