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Patient information A-Z

Important information

Before your appointment

  • Please follow the enclosed bowel preparation instructions carefully. Your bowel must be completely empty to allow the endoscopist to have a clear view.
  • Stop taking iron tablets seven days before the procedure. All other medication (including aspirin) should be taken as normal.
  • If you are taking, Warfarin or Clopidogrel or other blood thinning medication. please contact the Endoscopy Nurses when you receive this information on 01223 216515. You may need to stop you medication prior to your procedure. It you take Aspirin only please continue.
  • If you have diabetes please read the advice at the bottom of this page.
  • If you have implanted cardiac device such as a Pacemaker or Implanted Cardioverter Defibrillator please contact the endoscopy unit on 01223 216515.
  • If you have any questions about the procedure or find that you cannot keep this appointment please contact the endoscopy office between 09:00 and 17:00 Monday to Friday, telephone 01223 257080.

On the day

  • Drink as much fluid as you can, even on the day of the procedure.
  • If you have an afternoon appointment, please remember to take the rest of the bowel preparation first thing in the morning.
  • If you want to have sedation please ensure you have arranged an escort to take you home. We cannot sedate you if you do not provide details of your escort.

At the hospital

  • Please come to the endoscopy department, on level three of the Addenbrooke’s Treatment Centre (ATC).
  • Use the ‘Car Park 2’. The car park is busy early in the morning; please allow yourself enough time to arrive in time for your appointment. Take your parking ticket to the Endoscopy reception desk to have your ticket stamped; this will enable you to have discounted parking.
  • Please note you need to arrive 30 minutes prior to your appointment time for your pre procedure check. The length of time you will be here will vary enormously but expect it to be anything from two to four hours or more. Please ask your admitting nurse for further information during your admission check.

What is a colonoscopy?

Illustration of a colonoscopy
Illustration of a colonoscopy

Your doctor has requested this procedure to help investigate and manage your medical condition.

Colonoscopy is an examination of the colon, also called the large bowel or intestine. The last part of the colon leads into the rectum where faeces (stools) are stored before passing out of the anus (back passage).

The procedure involves passing a narrow flexible instrument through the anus into the colon to examine the colon lining. This allows us to see if there are any problems such as inflammation or polyps (a polyp is a bit like a wart). The procedure usually takes thirty minutes but times vary considerably. If it takes longer, please do not worry.

Sometimes it is helpful for diagnosis to take a sample (biopsy) of the lining of the bowel. A small instrument, called forceps, passes through the colonoscope to ‘pinch’ out a tiny bit of the lining (about the size of a pinhead). This sample is sent to the laboratory for analysis. It is also possible to remove polyps in a similar way. Most people find this completely painless.

Getting ready for the procedure

Non-urgent advice: Bowel preparation

Start taking the bowel cleansing preparation the day before the procedure as instructed in the leaflets:

Bowel preparation with Plenvu– Morning appointment

Bowel preparation with Plenvu– Afternoon appointment

You should expect frequent bowel movements starting within three hours of the first dose of the bowel preparation. It is advisable to stay at home when you take the bowel preparation and stay close to a toilet; make sure you have plenty of fluids in the house before taking the preparation.

Additional information for people with a colostomy

If you have a colostomy, you may find the bowel preparation easier to manage if you use a drainable colostomy bag. These can be obtained by contacting the stoma care nurses on 01223 216505. If you have had a colostomy you may be able to have the procedure without sedation and hence will not need an escort. However, if you wish to have a sedative, you must arrange an escort to take you home.

On arrival to the department

Please register your arrival with the receptionist, they will ask for your pre-procedure questionnaire. Some patients may arrive after you but be seen quicker; we have seven procedure rooms all undertaking different procedures therefore patients are not seen in arrival order.

Before your procedure you will meet one of the nurses who will ask you some health questions, explain the procedure to you and ask you to sign a consent form.

Once this is completed, you will be escorted to a single sex changing area. You will be asked to change into a gown and ‘dignity shorts’ ready for the procedure. Your escort cannot wait with you from this point and can leave the department until you are ready to go home.

You can change your mind about having the procedure at any time.


For many people colonoscopy is completed using intravenous sedation; however, some patients will undertake the procedure using entonox (gas and air). Sometimes the procedure can be uncomfortable, for example, if there is diverticular disease present or if the bowel has many loops – these situations may not be predictable before the examination. The options are:

  1. No sedation: is not recommended for this procedure however
  2. Entonox: also known as ‘gas and air’ is used to stop discomfort during procedures. It provides quick relief and allows you to be in control. You can leave the department after 30 minutes and can continue with your normal activities.
  3. Intravenous sedation: This will be administered via a plastic tube called a cannula, which is inserted into a vein, and make you feel relaxed and sleepy but not unconscious (this is not a general anaesthetic). This option means you may not be aware of the procedure.

The disadvantages to this option are:

  • You will need to stay whilst you recover which may take up to an hour or more.
  • You will need to be escorted home; your procedure will be cancelled if you do not have an escort.
  • The injection will continue to have a mild sedative effect for up to 24 hours and may leave you unsteady on your feet for a while.

Non-urgent advice: If you choose sedation:

If you choose sedation, you must arrange for a responsible adult to collect you from the department and take you home. You will not be able to drive yourself. You cannot be collected in a taxi without your escort present.

Please provide reception with the contact details of your escort, they need to be available to collect you from 90 minutes after your appointment time.

If you are entitled to use hospital transport, an escort is not required. Please inform the department prior to your appointment if you have arranged hospital transport.

What happens during the procedure?

You will be collected from the changing room by either the Endoscopist or one of the nursing team who will escort you to the procedure room. The team in the procedure room will introduce themselves and ask you some questions; this is to confirm you are ready and prepared to continue with the procedure.

We will ask you to remove any glasses and we will make you comfortable on a couch, lying on your left side with your knees bent. For your comfort and reassurance, a trained nurse will stay with you throughout the procedure.

If you are having sedation, the Endoscopist will give you the injection and we will give you oxygen through a facemask and a plastic 'peg' will be placed on your finger to monitor your pulse and oxygen levels. If you have chosen entonox the nurse will explain how to use it before the procedure commences.

We will then gently pass a flexible endoscope through your anus into your colon (large bowel). Air is put into your colon, this can give you some wind-like pains, but they will not last long. At this time, you might feel like you need to go to the toilet. Because of the bowel preparation you gave yourself, your bowel will be empty and so you will only pass some wind.

There may be periods of discomfort as the tube goes around bends in the bowel. Usually these will ease once the bend has been passed. If you are finding the procedure more uncomfortable than you would like, please let the nurse know.

In order to make the procedure easier you may be asked to change position (for example roll onto your back). When the procedure is finished, the tube is removed quickly and easily.

Minimal restraint may be appropriate during either of the procedures. However if you make it clear that you are too uncomfortable the procedures will be stopped.

Potential risks

Taking the bowel preparation might prevent the absorption of the oral contraceptive pill. Additional contraceptive precautions should be taken until the next period begins.

Colonoscopy procedures carry a small risk (one in 1000 cases) of bleeding or perforation (tear) to the bowel. These are more likely to occur after the removal of a polyp. On very rare occasions, this may require an operation, which may involve making a temporary opening (called a stoma) in the abdomen to allow the passage of waste (faeces).

Removing a polyp can sometimes cause bleeding although this is usually stopped during the procedure. Occasionally bleeding may occur when a patient has gone home and, even more rarely, some of these people may need a blood transfusion. Another rare complication is an adverse reaction to the intravenous sedative and pain relief medication.

Like all tests, this procedure will not always show up all abnormalities and, on very rare occasions, a significant abnormality may not be identified. If you have any questions about this please ask either at the time of the procedure or the person who referred you.

After the procedure

If you are unsedated or had entonox, we will take you to recovery and ask you to rest for approximately 30 minutes. We will give you a drink before you get dressed.

If you had sedation, we will take you to a recovery area while the sedation wears off. When you are sufficiently awake, we will give you a drink before you get dressed. You can then go home; this may be up to an hour following the procedure.

We advise you not to drive, operate machinery, return to work, drink alcohol or sign legally binding documents for a 24-hour period after the procedure. We also advise you to have a responsible adult to stay with you for the next 12 hours. You can eat and drink as normal.

You may feel a little bloated and have some wind-like pains because of the air in your gut; these usually settle down quickly.

We will always do our best to respect your privacy and dignity, eg with the use of curtains. If you have any concerns, please speak to the department sister or charge nurse.

When will I know the result?

If you did not have sedation the endoscopist or endoscopy nurse will give you information during and immediately after the procedure. If you had sedation, we will tell you about the procedure in the recovery area when you are awake. If you would like more privacy, we will take you to a private room.

The sedation can affect your ability to remember any discussion. If you would like someone with you when you talk to the endoscopist or endoscopy nurse please inform the nurse looking after you who will arrange for you to be seen in a private room with your escort when they arrive.

The final results from biopsies or polyp removals will be given to you either by the healthcare professional who requested the procedure at a clinic appointment or by letter. These results can take several weeks to come through. You should discuss details of these results and any further treatment with that person.

After discharge

We will provide you with an information sheet on discharge which will detail who to contact if you require any assistance after the procedure.


In some cases, depending on individual factors such as the symptoms present and the presenting condition, the alternative to a colonoscopy is a Computerised Tomography (CT) colon scan.

For more information:

  • Contact the endoscopy office between 9:00 and 17:00 on 01223 257080.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151