Colonoscopy / Sigmoidoscopy

What is a Colonoscopy?

Colonoscopy is a test where an endoscopist (a doctor or nurse) looks into your colon. The colon is sometimes also called the large intestine or large bowel. This procedure 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. The procedure is used to diagnose the causes of unexplained changes in bowel habits. It is also used to look for polyps and early signs of cancer in the colon and rectum.

During the procedure the endoscopist uses a colonoscope which is a thin, flexible, telescope. It is about as thick as the little finger. The colonoscope is 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).

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. This is normal and there is no need to be embarrassed as the staff will expect this to happen.

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. You will usually be given a sedative to help you to relax. This is normally given by an injection into a vein in the back of your hand. The sedative can make you drowsy but it does not ‘put you to sleep’. It is not a general anaesthetic. 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 the sedative to work, for the colonoscopy itself, and to recover. A colonoscopy does not hurt, but it can be a little uncomfortable, particularly when the colonoscope is first passed into the anus.

Before 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 2 sachets of liquid bowel preparation to clear the bowel the day before the procedure and drink plenty of fluid. If you have a morning appointment, please follow the instructions inside the box. If you have an afternoon appointment, please follow the enclosed instructions.

Occasionally following the bowel preparation you may experience abdominal pain or a headache it is fine to take paracetamol or similar painkillers.

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

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.


If you are taking Warfarin tablets, please inform us as soon as possible, as our doctors may decide that it is necessary for you to stop taking your tablets for a limited time before the procedure.

Clopidogrel (Plavix)

If you are taking Clopidogrel, please inform the Gastroenterology Unit as soon as possible, as our doctors may decide that it is necessary for you to stop taking your tablets for a limited time before the procedure.


If you suffer from diabetes, please inform the Gastroenterology Unit as soon as possible, as it may be necessary to change the time of your appointment or be admitted to hospital a day before your procedure for treatment.


If you are pregnant or breast-feeding please contact the Gastroenterology Unit.


Enclosed is a consent form for you to read before you come for your appointment. This is to ensure that you understand the test and its implications/risks. Please bring it back with you. If you have any queries you can phone the unit or you will be able to ask a qualified member of staff when you sign the form before your procedure.

What are the risks and complications?

Most colonoscopies are done without any problem. You may feel tired or sleepy for several hours afterwards caused by the sedative. You may pass a small amount of blood from your anus if a biopsy was taken, or a polyp was removed.

Occasionally, the colonoscope may cause damage to the colon. This may cause bleeding, infection, and rarely, perforation. If any of the following occur within 48 hours after a colonoscopy, it is important that you consult a doctor immediately.

· abdominal pain.

· fever (raised temperature).

· passing a lot of blood from your anus

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 the results of this may take several days. Details of the results and any necessary treatment will be sent to your GP or a further outpatient appointment may be necessary.

You will be left to rest as you may feel sleepy if you have had sedation. If you chose to have sedation it is a good idea for the person taking you home to be with your when you speak to the endoscopist. If sedation has been used, people find they forget what has been said and may not even recollect having the test at all.

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.

If you have had sedation you must have someone to escort you home and stay with you for the 24 hours after your test. Following sedation you must not do any of the following for 24 hours:

– Drive a motor vehicle

– Drink Alcohol

– Operate Machinery

– Sign Legal Documents


What our patients say

We were very pleased to receive first class reassurance, advice, treatment, and aftercare. We would definitely recommend Dr. Campbell to anyone in need of an excellent Doctor. His secretary Sarah was also very helpful and most competent.

— Patient
BMI The Alexandra Hospital

Combining superb expert knowledge , outstanding technical skills (colonoscopic endoscopic mucosal resection), extremely good listening and communication skills with a down to earth practical approach to any difficulties, Dr Willert made me fully very safe and confident in his care. I am very pleased to have been referred to him with my problem.

— Patient
Spire Manchester Hospital