Patient Information Leaflet


What is a Colonoscopy?

Colonoscopy is a test which allows the endoscopist to look inside your entire large intestine, from the lowest part, the rectum, all the way up through the colon to the lower end of the small intestine.

Why is this procedure done?

The procedure is indicated in the following

  • Unexplained changes in bowel habits.
  • Bleeding from the back passage.
  • Weight loss.
  • Chronic constipation or chronic diarrhoea.
  • History of polyps.
  • Screening for cancer.

Preparation for the procedure

Colonoscopy is usually done as an outpatient or day case. Before your procedure you will be asked to change into a hospital gown and to lie on your left side with your legs in a curled position. The procedure itself usually takes about 20-30 minutes. But, you should allow at least two to three hours for the whole appointment to prepare, give time for any sedative to work, for the colonoscopy itself, and to recover


  • You will normally have sedation, which is a medicine to help you to relax. This is given by injection. Whilst this will make you drowsy it does not ‘put you to sleep’ like a general anaesthetic.
  • Someone must stay with you for 24 hours following your procedure to look out for any complications
  • During this time, you are advised against doing the following: Drive a motor vehicle, Drink Alcohol, Operate Machinery OR Sign Legal Documents.

Preparing for the procedure

To allow a clear view the whole large bowel (colon)must be completely empty of waste material. It is essential that you drink the bowel preparation solution prescribed. Occasionally following the bowel preparation you may experience abdominal pain or cramps. If you are experiencing problems with the bowel preparation you can call the endoscopy unit.

Medicines and Medical Conditions

It is important you bring a list of your current medication with you so that you can give it to the nurse on arrival.

Iron tablets (Ferrous Sulphate)

If you are taking iron tablets please stop taking them for TWO WEEKS BEFORE the procedure. This is because iron coats the colon, making it difficult to see the lining.
Please inform the doctor if you are on the following medication:

Warfarin / Phenidione / Clopidogrel (Plavix), or any other blood thinning agent


It is important you bring a list of your current medication with you so that you can give it to the nurse on arrival.


If you are pregnant or breast-feeding please inform your doctor

How is it done?

  • The back passage will be examined using a finger before colonoscope is inserted.
  • During the procedure the endoscopist uses a colonoscope which is a thin, flexible, telescope. It is about as thick as the little finger. The colonoscopeis passed through the anus and into the colon. It can then be pushed all the way round the colon as far as the caecum.
    (where the small and large intestine meet).
  • The colonoscope contains fibre optic channels which allows light to shine down so the operator can see inside your colon. It also has a 'side channel' which allows the endoscopist to take small samples of tissue (a biopsy) from the inside lining of the Colon.

Biopsies do not hurt as the lining of the colon does not have the same pain sensation as your skin.

However you may experience some cramping as air is introduced through the scope and the scope is passed through twisty segments of the colon. The air is needed to permit the endoscopist to advance the scope along the colon. This may also make you feel bloated, and may cause you to pass wind.

What are the risks and complications?

Most colonoscopies are done without any problem.

  • If you have had a sedative you may feel tired or sleepy for several hours afterwards.
  • Bloating and abdominal discomfort last for few hours.
  • You may pass a small amount of blood from your anus if a biopsy was taken, or a polyp was removed. Occasionally, the colonoscopemay cause damage to the pypy, pyg colon. This may cause bleeding,( severe bleeding may occur in less than 1: 300 cases, which can require a blood transfusion and even less commonly surgery)
  • Perforation(making a hole in the lining of the bowel). This is an uncommon complication occurring in approximately 1 in 1000 cases, however risk increases if polypectomy or other therapy is performed. This may sometimes require an operation to repair the damage.
  • If any of the following occur within 48 hours after a colonoscopy, it is important that you consult a doctor immediately.
    • abdominal pain. (In particular if it becomes gradually worse, and is different or more intense to any 'usual' pains that you may have.)
    • fever (raised temperature).
    • passing a lot of blood from the back passage.

After the procedure

  • The endoscopist will talk to you at the end of the procedure, explaining what has been found. If a biopsy has been taken, further outpatient appointment may be necessary to discuss the results
  • Once you have returned home, or back to your ward you may begin to eat and drink normally and resume your normal medication, unless instructed otherwise by the Doctor