Gastroscopy – The Procedure Explained

The aim of this leaflet is to help you make a choice about having a gastroscopy. It describes how a gastroscopy is carried out and explains the benefits and risks.

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Procedure Information

Please read this leaflet as soon as possible and well in advance of your appointment. If you do not follow the advice on how to prepare for your procedure it may not be possible to do it and you may have to return on another day.

Please bring this leaflet and consent form with you when you attend for your appointment.

Helpline or enquiries (8.30am to 5.00pm Monday to Friday)

For appointments and general enquiries

Boston           01205 445072

Grantham      01476 464366 / 01205 445072

Lincoln           01522 573849

Louth              01522 573849 / 01507 631415 / 631437

For procedure related enquiries (8.30am to 6.00pm Monday to Friday)

Boston           01205 446559

Grantham      01476 464085

Lincoln           01522 573016 / 01522 512512 ext 458669

Louth              01507 631236

For more information please see:

Aim of the leaflet

The aim of this leaflet is to help you make a choice about having a gastroscopy. It describes how a gastroscopy is carried out and explains the benefits and risks.

It is important that you follow the instructions about stopping food and drink before the test. This is for your safety. If you do not follow the advice given it may not be possible to do your procedure and you may have to return on another day.


You have been advised to have an investigation known as a gastroscopy.

If you are unable to keep your appointment, please notify the department as soon as possible as your appointment may be used for someone else. The booking team will arrange another date and time for you. Please bring this booklet with you when you attend.

Enclosed with this information leaflet is a consent form. Your signature is needed for the test to go ahead.

The consent form is an important document.  Please read it carefully together with the information in this leaflet. Please bring both the consent form and leaflet with you to your appointment.

We may contact you a few days before your appointment to discuss the procedure and preparation in more detail. You will also be given the opportunity to ask questions in the department when you attend for your appointment.

In case of any problems please contact the relevant endoscopy unit (telephone numbers are given on page 2 of this booklet).

What is a gastroscopy?

The procedure is called OesophagoGastroDuodenoscopy (OGD) known more simply as gastroscopy or endoscopy.

It involves looking at the upper part of the gut which includes the oesophagus (food pipe), stomach and the first part of your small bowel (duodenum) with a narrow flexible tube called a gastroscope. The scope is about the thickness of a little finger and is passed through the mouth and down into the stomach. The procedure is performed by, or under the supervision of, a specially trained doctor or nurse (endoscopist). A light and camera at the end of the gastroscope relay pictures onto a television screen.

Samples of tissue (biopsies) may be taken during the test. This is done through the scope. It does not cause any pain and the samples are kept to be looked at under a microscope in the lab. Photographs may be taken for your clinical records and may be used for teaching purposes.

The procedure generally takes 5 to 10 minutes.

We aim to make the procedure as comfortable as possible for you. Some people choose to have sedation (injected into a vein), while others prefer to only have local anaesthetic throat spray. More information about sedation and throat spray can be found later in this leaflet.

What are the benefits of having a gastroscopy?

If you have been troubled by symptoms the cause may be found and help decide if you need treatment or further tests.

Gastroscopy can also be done:

  • as a follow up check for certain conditions affecting the stomach or oesophagus
  • if a scan or x-ray has shown there may be something wrong in the upper part of the gut, to allow a closer look at the area

What are the risks of the procedure?

Complications are rare. These may be linked to the procedure itself or the sedation medicine.

Sore throat, damage to teeth or bridgework (to reduce this risk your teeth will be protected with a mouth guard).

Sometimes the procedure cannot be completed and a repeat test or an alternative test is needed.

Perforation or tear of the lining of the stomach or oesophagus (about 1 for every 9000 cases). If this happens you may need an operation.

Bleeding may happen when a biopsy is taken. It usually stops on its own but may need cauterization or injection treatment. In some cases a blood transfusion may be needed.

There is a small chance that a cancer may not be seen.

Sedation can sometimes cause problems with breathing, heart rate and blood pressure. If any of these problems do occur, they are usually short lived. Careful monitoring by a specially trained endoscopy nurse means that potential problems are picked up early and dealt with quickly. The sedation can also cause small food particles to fall into the lungs which can trigger an infection (aspiration pneumonia). That is why it is important for your stomach to be empty (see advice below on preparing for the investigation).

In extremely rare cases the procedure can lead to death. Current evidence suggest this may happen in around 1 in every 10,000 examinations.

What are the alternatives?

A barium meal x-ray is an alternative test but this involves some radiation exposure. It does not give the same information as a gastroscopy and biopsies cannot be taken.

Preparing for the investigation

Eating and drinking

For your safety, to reduce the risk of complications and give clear views, your stomach must be empty. Do not have anything to eat for at least 6 hours before the test and only have a light meal before this time. You may have small amounts of water up to 2 hours before your appointment time but other fluids such as milk are NOT allowed (even in tea and coffee) as they coat the stomach. You should have nothing to drink for at least 2 hours before the test.  If you do not follow this advice, your procedure will be rearranged.

If you are having a colonoscopy or flexible sigmoidoscopy at the same appointment as your gastroscopy, please follow the bowel preparation instructions given. You may drink water up to 2 hours before your appointment time.

What if I take regular medication?

Your routine medication should be taken as usual with a small amount of water.

Acid reducing medication (PPIs)

It is useful if you stop taking tablets that reduce the acid in your stomach for 2 weeks before the gastroscopy.

If your symptoms make this difficult or if you are having a follow-up gastroscopy to check the healing of an ulcer or Barrett’s Oesophagus, then please continue your acid reducing medication right up to the procedure.

Blood thinning medication (anticoagulants)

Sometimes these medications need to be stopped and if this is the case the person who referred you for the test should have given you clear instructions. If you are unsure please contact your consultant’s secretary. For your safety, if the correct instructions are not followed, it may not be possible to do the gastroscopy and you may have to return on another day.

Warfarin: unless you have been advised to stop this medication, continue taking it and have your INR checked within the week before the test. The procedure may be cancelled if your INR has not been checked within the last 7 days. It should be within your target range. If you have been advised to stop your Warfarin you should do so for 5 full days before the procedure (take your last dose 6 days before the procedure) and have your INR checked the day before the procedure. It needs to be less than 1.5 for the procedure to go ahead. IMPORTANT: please bring your yellow book to the appointment.

Dabigatran, Rivaroxaban, Apixaban, Edoxoban: please do not take on the morning of the procedure. If you have been advised to stop taking this medication you should take your last dose 3 days before the procedure.

Clopidogrel (Plavix), Prasugrel, Ticagrelor: these medications can generally be continued but if you have been advised to stop you should do so for 7 full days before the procedure (take your last dose 8 days before the procedure).


If you have diabetes controlled on insulin or tablets, please make sure the relevant endoscopy appointments’ team is aware so that the appointment can be made towards the beginning of the list. You will find more advice later in this leaflet.

Throat spray and conscious sedation

Anaesthetic throat spray and conscious sedation are available to improve your comfort during the procedure. Some people choose to undergo the procedure with throat spray alone.

Anaesthetic throat spray

This is a local anaesthetic spray which numbs the back of the throat. It has an effect very much like a dental injection.

If you choose to have only throat spray you can go home on your own almost immediately after the procedure. You are allowed to drive and may carry on as normal, but must not eat or drink for about an hour afterwards until the sensation in your throat is back to normal. You will be given more detailed instructions after the procedure.

Intravenous conscious sedation

The sedation is administered into a vein in your hand or arm just before the start of the procedure. This will not make you go to sleep but should help you to feel more relaxed. It is important that you are awake for the procedure so that you are able to follow simple instructions.

Please note if you have sedation into the vein, you will need someone to accompany you home and stay for at least 4 hours and if possible overnight. You are not allowed to take part in the following activities for 24 hours afterwards:

  • drive a vehicle
  • go to work
  • look after children on your own
  • operate heavy/dangerous machinery (including a cooker)
  • drink alcohol
  • sign legally binding documents

What happens when I arrive?

When you arrive for your appointment please book in at reception.

It is our aim for you to be seen as soon as possible after your arrival. However, if the department is very busy your appointment may be delayed. The department looks after emergency patients who will be seen first if needed.

A nurse will take you through to the admission room and ask you about your general health to check if you are fit to have the procedure. You will also be asked about your plans for getting home afterwards.

The nurse will make sure you understand the procedure and discuss any further concerns or questions you may have. If you are happy to go ahead, you will be asked to sign your consent form.

Your blood pressure and heart rate will be checked and if you are having sedation a cannula (small plastic tube) will be inserted into a vein (sometimes this is done in the procedure room).

What will happen during the procedure?

The nurse will take you through to the procedure room where you will be able to ask any final questions. If you have any dentures or tongue piercings you will be asked to remove them. Any remaining teeth will be protected by a small plastic mouth guard which will be inserted just before the examination commences.

A local anaesthetic will be sprayed onto the back of your throat. It works quickly and will make your tongue and throat feel numb.

You will be asked to lie on your left side and a probe will be placed on your finger to monitor your oxygen levels. You will receive oxygen through the nose and if you are having sedation it will be given into the cannula in your vein. Any saliva or other secretions produced during the procedure will be removed using a small suction tube, like the one used at the dentist.

The endoscopist will pass the gastroscope into your mouth, down your oesophagus into your stomach and then into your small bowel. Your wind pipe is deliberately avoided so you will be able to breathe normally throughout.

What will happen after the procedure?

You will be taken to a recovery area where your heart rate, oxygen levels and blood pressure will be monitored. Before you leave the department, the nurse or doctor will explain the findings and if any medication or further tests are required.

For safety, following the throat spray, you must not have anything to eat or drink for about an hour after the procedure until the sensation in your mouth and throat has returned to normal.

It is strongly advised that your first drink after the procedure is cold and that you sip it to ensure you do not choke. You will be given more detailed advice about this after the procedure.

You may have a sore throat from the insertion of the tube which can last up to 48 hours. This will wear off but simple lozenges may help. You may also feel bloated if some of the air has remained in your stomach. To help this, sit upright and if possible walk around.

Pain relieving tablets, such as paracetamol, may be taken according to the manufacturer’s instructions.

Most people who opt out of sedation are able to return to work after the procedure. This varies from person to person.  If you have sedation you are advised not to return to work for 24 hours afterwards.

Guidance for people with diabetes

Treatment by diet alone

If you control your diabetes with diet alone, you simply need to follow the instructions given earlier in this booklet to prepare for your gastroscopy.

Treatment with tablets and/or insulin

You may need to adjust your diabetes medication on the day of the procedure to reduce the risk of hypoglycaemia (‘hypo’ or low blood sugar level). As a result your blood sugar may be a little higher than usual but this is only temporary to maintain your blood sugars during the procedure and you should be back to your usual level within 24 to 48 hours. If needed please contact the Specialist Diabetes Nursing Team on 01522 573074 well in advance of the appointment for advice.

Carrying glucose to treat hypoglycaemia

On the day of the procedure carry glucose tablets in case of hypoglycaemia. These are absorbed quickly through the tissues of the mouth and if sucked they will not interfere with the procedure. If you have symptoms of low blood sugar suck 4 to 6 tablets initially (do not chew), followed by a further 4 to 6 if your blood sugar is still low after 10 minutes.

Blood glucose monitoring

If you usually test your blood sugar level, check it as usual on the morning of the procedure and bring your equipment with you to the appointment. If you do not usually test your blood, do not worry, your blood sugar will be checked when you arrive for the procedure.

Please report to the nursing staff if you have needed glucose before arriving for your appointment and tell them immediately if you feel ‘hypo’ at any time during your visit.

What must I remember?

  • If you are unable to keep your appointment please notify the endoscopy department as soon as possible. Telephone numbers are given at the beginning of this leaflet.
  • Follow the instructions about stopping food and drink or your procedure may be postponed.
  • It is our aim for you to be seen as soon as possible after your arrival. However, the department is very busy and your appointment may be delayed. If emergencies occur, thesepatients will be seen before less urgent cases.
  • If you have opted for sedation into the vein please arrange for someone to collect you and for someone to stay overnight if possible. Your activities afterwards are limited for 24 hours afterwards (see section on sedation above).
  • The hospital cannot accept any responsibility for the loss or damage to personal property during your time on the premises.

If you have any questions or concerns, or are worried about any symptoms you experience after the test, you may ring the enquiry numbers on page 2 of this booklet. Out of hours please contact the NHS non-emergency service on 111.