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Dual procedure—gastroscopy and colonoscopy (West Mid)

*Patients are no longer required to take a covid swab test before an endoscopy procedure. However, we will continue to assess patients on arrival. If you are symptomatic, we will ask you to take a covid swab test before your procedure takes place.

You have been advised by your GP or hospital doctor to have a dual gastroscopy and colonoscopy examination.

What is a gastroscopy?

The first procedure you will be having is a gastroscopy, also known as an OGD.  This is a test in which a long flexible telescope called an endoscope is passed through the mouth allowing the Endoscopist to look directly at the lining of the oesophagus (gullet), stomach and duodenum (small bowel).

What is a colonoscopy?

A colonoscopy is a diagnostic test in which a long flexible telescope called an endoscope is passed through the back passage (anus) allowing the doctor to look directly at the lining of the large bowel (colon).

Sometimes a biopsy - sample of tissue – is taken for analysis (testing) in the laboratory. The tissue is removed through the endoscope using tiny forceps. This is not painful.

Some people will require treatment through the endoscope to treat/prevent bleeding, or to dilate up the oesophagus. If this is needed the procedure will be explained and may take longer.

What options are available for the procedure?

There is a considerable variation in the way people react to this procedure and the sedation. General anaesthesia is not required. The procedure is safe but may be unpleasant and, at times, uncomfortable.

Throat spray: If you chose this option you will be fully awake during the examination. The endoscopist and nurses will talk you through it. A local anaesthetic spray will numb the back of the throat, helping the endoscope to go down.

Sedation via a needle: If you chose this option we will give you a sedative via a needle in your arm. This is not a general anaesthetic but will make you relaxed and may make you feel sleepy. If you have sedation you will need to rest on a trolley, in recovery area, for at least an hour afterwards until the effects of the sedation have worn off.

The nurses will give you written discharge information. This includes the advice that for 24 hours after sedation you should not drive, ride a bicycle, operate machinery, take sedatives, drink alcohol, or sign legal documents. If you are having sedation, you must organise for someone to take you home after the test and be with you for 24 hours.

Entonox (gas and air): If you chose this option you will be given Entonox to breathe in as needed during the procedure. The gas takes immediate effect and helps relieve discomfort but does not make you feel sleepy. If you chose this option you do not need an escort to take you home after.

What should I do before I come in?


You will receive a link via DrDoctor on your mobile phone soon. Please click on the link and complete your form remotely as soon as you can. If you do not have a smart phone you will not be able to access the link a nurse will call you or ask you to come in for a face to face pre-assessment


The success of the colonoscopy depends on how clean your colon is. Cleansing your colon before a colonoscopy is called bowel preparation. It involves drinking sachets of bowel preparation (laxative) to empty your bowels before your test. It is very important you read and follow the bowel preparation instructions and low fibre diet before your procedure. If your bowel is not empty enough your procedure may be cancelled and repeated on another occasion. 

Your prep will be posted to you once the nurses have a completed a telephone pre-assessment with you and you have confirmed your attendance. You may be asked to collect your prep from the unit should it not arrive on time.

If we are unable to contact you for the pre-assessment and you do not respond to texts or voicemails, your procedure will be cancelled and you may be discharged back to your GP.


If you are having sedation, remember to arrange for an adult to take you home after the test and be with you for 24 hours.


7 days before procedure – stop taking the following medicines

  • Omeprazole (Losec), Lansoprazole (Zoton), Esomeprazole (Nexium)
  • Iron tablets (including vitamin tablets that contain iron)
  • Bulking agents (Fybogel or Regulan).

4 days before procedure stop taking any constipating agents (loperamide, codeine phosphate etc). 

If you are diabetic please let us know in advance. 

If you are taking any of the following medicines, please inform a member of the Endoscopy team for further instructions:

  • Warfarin
  • Rivaroxaban
  • Apixaban
  • Dabigatra
  • Edoxaban
  • Clopidogrel
  • Prasugrel
  • Ticagrelor
  • Aspirin

Any other medication used to thin the blood (anti –coagulant).

2 days before procedure stop taking:

  • Ranitidine (Zantac)
  • Cimetidine (Tagamet)


You will need to follow a restrictive low fibre diet 4 days before your procedure.  Please see our separate dietary sheet. If the bowel is not empty enough, the procedure may be cancelled and repeated on another occasion.

Please avoid all high fibre foods; it is essential that your bowel is clear for an accurate diagnosis and treatment.  Abnormal changes may be tiny, so even small amounts of residual stool could potentially disguise something important.

What will happen when I come in?

On arrival to the endoscopy unit please report to reception where the receptionist will check your personal details. You will be asked to take a seat in the waiting area until you are collected by a nurse, and taken through to one of our admission rooms.  You do not need to bring anyone with you to your appointment, unless they are acting on your behalf e.g. interpreting for you.  Please leave any valuables at home, as we cannot be responsible for any valuables lost whilst you are in the unit.


On admission a nurse will review your pre-assessment form (Medical history and current medications) that you should have completed online or over the telephone.  We will take your blood pressure, pulse and ask you to get changed into a gown and dignity shorts. Dignity shorts are specially designed to maintain patient modesty before, during and after a procedure.


Prior to the test you will be seen by the endoscopist. This is an opportunity to discuss the test before you sign a consent form. Please ask any questions you may have. It is important that you understand what is going to happen.

What will happen during the test?

In the procedure room you will lie on a trolley (narrow bed), on your left side. Two nurses and the endoscopist will stay with you throughout both tests.

During the test you may be given oxygen through little prongs that fit just inside your nostrils. Your blood pressure, pulse and oxygen levels will also be monitored.


You will be asked to bite on a small plastic mouthpiece to help keep your mouth open. This will also help to protect your teeth during the test. Dentures have to be removed if they are loose.

When the endoscope is passed through your mouth it is likely to be uncomfortable. It may make you feel sick or you may retch. The endoscope will not interfere with your breathing.

During the test air is passed down the endoscope into your stomach to get a clear view. This may make you burp. The air is sucked out at the end of the test.  If you get a lot of saliva in your mouth, the nurse will clear it using a sucker (the sort of tube that is used when you go to the dentist).


There is a small risk of complications during the procedure. There is an extremely small risk of bleeding (haemorrhage) and a tear in the lining of the bowel (perforation) occurs in 1 in 1500. These complications are rare, but may require urgent treatment, blood transfusion or an operation. It may be necessary to remove polyps. If this happens, the risks are slightly higher, bleeding in 1 in 50 or a tear in 1 in 250.

Occasionally the procedure cannot be completed and we would normally recommend a special CT to look at the bowel (CT pneumocolon).

Do I need to be escorted home?

If you have sedation you must have an adult escort collect you from the unit and be with you for 24 hours. Please ensure the nurses have the contact details for your escort prior to the procedure. A nurse from the unit will call your escort once you are ready for collection.

Please note:  You will not be able to have sedation if you do not have an escort arranged to collect you. We cannot escort you home.

How long will I be in the endoscopy unit?

Both procedures are usually completed between 30-60 minutes; however please expect to be in the department for 2-3 hours – having pre-procedure checks, the procedure and for recovery after the procedure. 

Please note your appointment time in Endoscopy is approximate because some procedures may take longer than expected and emergency procedures need to take priority.

What happens to my medication?

We will talk to you before you go home about any changes/additions to your medications

After you go home

You may experience bloating and abdominal discomfort for a few hours after the test. This is because of the air that is used to expand and inflate your stomach and bowel during the test. These symptoms are often relieved by the passing of wind.

If you have had a polyp removed or a biopsy, you may experience a little bleeding from your back passage.

Some patients have told us that they experience discharge from their back passage or an urgent need to open their bowels after the procedure. You may therefore like to bring a change of underwear with you.

If the pain continues or are passing large amount of blood, or you have concerns or questions, please contact the Endoscopy Unit from 8am–6pm on 020 8321 2585/5191 - after 6pm call 020 8560 2121 and ask for the on call gastroenterologist.

This leaflet has been written by the staff working in the Endoscopy Unit at West Middlesex University Hospital. We hope you find it useful. If, after you have read it, you have any questions or concerns; please contact us on 020 8321 2585/5191.

If you would like to change your appointment time or date please contact the endoscopy booking team on 020 8321 5752 or email us

How to find us

The Endoscopy Unit is located on the ground floor of the Main Hospital Building in the East Wing.

Getting here:



Lucy Wilson