A gastroscopy is a procedure which allows us to look directly at the upper part of your digestive system – the oesophagus (or food pipe), stomach and duodenum (the first part of the small bowel). The test is sometimes called an endoscopy or an OGD (oesophago-gastro-duodenoscopy). The endoscopist passes a thin, flexible tube with a very small camera at the end (called a gastroscope or endoscope) through your mouth and into your stomach. The procedure takes about five to ten minutes. The endoscopist may take a small tissue sample.
Gastroscopy is a test which helps your doctor find the cause of symptoms including:
- Indigestion
- Heartburn
- Losing weight without trying
- Being sick (vomiting)
- Anaemia
- Difficulty swallowing
- A lump in the throat
Before you agree to this procedure, you will have the opportunity to speak with the endoscopist so that you are aware of the reason the procedure is being done, the alternatives and the problems that can occur. For most people a gastroscopy is a simple and safe procedure. Unusual complications do sometimes occur and include chest infections, damage or perforation (a hole) in the oesophagus, stomach or duodenum wall, allergy to sedative medication, bleeding or damage to teeth. Although gastroscopy is the best procedure to help diagnose many problems, no procedure is perfect. There is a small risk that we might miss a lesion or other important finding during your procedure.
If you decide not to have the procedure it is very important that you inform the Endoscopy Unit as soon as possible and also the clinician who requested it. If the procedure is not performed then it is possible that the cause of your symptoms will not be diagnosed.
Sometimes a CT scan can be performed as an alternative to gastroscopy or you may have a barium swallow test (where the barium will coat your digestive system and show up the outline of the organs on an X-ray). However, these tests often provide different information and are often done as well as a gastroscopy. One disadvantage is that tissue samples cannot be taken with a scan, whereas this can be done with a gastroscopy.
Please do not eat for six hours before the procedure and do not drink four hours before the procedure (this includes milk in any drink). You may drink sips of water up to two hours before the gastroscopy. If you are also having a colonoscopy you should stop eating as instructed in the colonoscopy information leaflet. Please bring a list of all the medications you are currently taking with you on the day of your gastroscopy.
If you would like sedation for the gastroscopy, please arrange for someone to take you home and be with you for 24 hours after the procedure.
If you are taking any blood thinning medications such as warfarin, clopidogrel, rivaroxaban, apixaban or any others you should continue these unless we give you specific instructions about stopping them.
If you are diabetic and take insulin, it is important that you continue taking your insulin but it is suggested that you reduce your doses on the night before and on the day of the test. If you take diabetic tablets, please do not take them on the day of the gastroscopy until after it has been done.
Please continue taking acid reducing medications such as omeprazole and lansoprazole unless you are told to stop them.
When you arrive at the Endoscopy Unit please report to the reception. From there a nurse will take you to admissions, check your personal details, check your blood pressure, and you will be asked to change into a hospital gown. When it is time for your gastroscopy you will be taken to the consenting room where you will meet the endoscopist and be asked to sign a consent form.
Sometimes due to emergencies and other unforeseen circumstances your appointment may be delayed. We try our best to see everyone on time but please understand that delays can occur and we ask for your patience in these circumstances.
By law we must ask you to sign a consent form. This confirms that you agree to have the procedure and understand what it involves. The endoscopist will explain all the risks, benefits and alternatives before he or she asks you to sign the consent form. This is also an opportunity for you to ask the endoscopist any questions you may have regarding the procedure.
At this stage you will be asked whether you would like sedation or throat spray to numb the back of the throat. Throat spray does not sedate you and therefore you will be able to go home directly after the procedure. Sedation helps to relax you and is given via a needle in the back of the hand or arm. You will feel sleepy but you will not be unconscious and are usually aware of what is going on around you.
From there, we will take you into one of the endoscopy rooms. You will be able to take your belongings with you or they may be left with friends or relatives. Friends and relatives can wait in the waiting room.
If you are having throat spray, a local anaesthetic will be sprayed onto the back of your throat and you will then be asked to lie on the trolley, on your left side.
After a few seconds your throat will go numb, which can sometimes feel a little unpleasant. You will also need to remove glasses or dentures if you have them. One of the nurses will attach some equipment to you so we can monitor your blood pressure and your oxygen levels.
If you are having sedation, the endoscopist will administer the sedation via a small needle in the back of your hand. This will take a few minutes to work. You may also be given a small amount of oxygen during the procedure.
The endoscopist will start the procedure by passing the camera into your mouth. The endoscopist will put air into the stomach to make it easier to see the stomach lining.
It should not be painful but it may feel uncomfortable. The pressure of the endoscope on the back of the throat can be uncomfortable, as can air in the stomach.
If you have had sedation you will be taken to the recovery area. You will be kept there for approximately one hour so the effects of the sedation can wear off. Your blood pressure and oxygen levels will be monitored during this time.
If you have had throat spray, the nurse will accompany you to the discharge lounge and you will be able go home immediately. Unless you are unsteady on your feet or usually require assistance with walking and travelling, you will be able to go home unaccompanied. You will need to wait until the numb feeling has worn off before eating and drinking.
In both cases, one of the doctors or nurses will come to explain the results of your gastroscopy. We will give you an advice sheet for aftercare and details of who to contact should you have any problems.
If you have had sedation you must bring someone with you who can to take you home and stay with for 24 hours after the procedure.
Once you arrive home you may eat and drink as normal.
Do read 'Do I continue taking my medicines?' regarding medication.
Do ask for an interpreter if you require one, hospital policy states family or friends cannot interpret on behalf of the patient.
Do ensure you have someone to take you home and stay with you after the procedure, if you would like to have sedation.
Do not drink milk four hours before the procedure.
Do not bring large sums of money or valuables to the hospital as we cannot accept responsibility for loss or damage.
Do not drive for 24 hours if you are having sedation. Please have someone to take you home in a car, taxi or public transport.
Do not drink alcohol for 24 hours after sedation is given.
Do not drive a car or operate heavy machinery for 24 hours after sedation is given.
If you have any problems after the procedure such as bleeding, black tarry stools or abdominal pain please contact us as soon as possible.
Contact information is provided below.
Endoscopy Booking Team (Monday to Friday 09:00-17:00)
Direct line: 020 3456 7022
Switchboard: 08451 555 000 / 020 3456 7890 ext. 67022
E-mail: uclh.
Endoscopy Recovery (Monday to Friday 09:00-17:00)
Direct line: 020 3447 3282
Switchboard: 08451 555 000 / 020 3456 7890 ext. 73282
Address: Endoscopy Unit, University College Hospital, 2nd Floor Podium, 235 Euston Road, London, NW1 2BU
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Page last updated: 16 June 2025
Review due: 01 June 2027