Expert reviewer, Dr Ian Arnott, Consultant Gastroenterologist
Next review due November 2021

A gastroscopy is a procedure that looks inside your oesophagus (gullet), your stomach and the first part of your small intestine (duodenum). It’s a type of endoscopy, which means it’s carried out using a narrow, flexible tube called an endoscope. This has a light at the end, and a camera to allow your doctor to see images of your insides on a video monitor.

You might also hear a gastroscopy being called an ‘upper gastrointestinal endoscopy’ or an ‘oesophago-gastro-duodenoscopy (OGD)’.

Why a gastroscopy is used

A gastroscopy can be used to investigate symptoms you may be having. It can also be used to diagnose certain medical conditions or as a treatment. You can find out how a gastroscopy is carried out in the section below on ‘What happens during a gastroscopy?’.

Your doctor may recommend you have a gastroscopy to find out why you’re having certain symptoms. These include:

  • indigestion (acid reflux or discomfort in your upper tummy) that doesn’t go away with treatment
  • difficulty or pain when you swallow (dysphagia)
  • pain in your upper abdomen (tummy)
  • being sick (vomiting) repeatedly
  • vomiting blood or having very dark tar-like blood in your faeces (melaena)

A gastroscopy helps your doctor to confirm or rule out suspected medical conditions such as peptic ulcers, coeliac disease, Barrett’s oesophagus, and cancer of the oesophagus or stomach cancer. In some cases, your doctor may take small samples of tissue (a biopsy) during the endoscopy.

Although a gastroscopy is usually done to diagnose the cause of your symptoms, your doctor can also use a gastroscopy to carry out certain treatments. These include stopping bleeding, removing small growths and widening your oesophagus if it has become narrowed. For more information, see our FAQ below: Can my doctor treat my condition during a gastroscopy?

Preparing for a gastroscopy

A gastroscopy is usually done as a day-case procedure in hospital. This means that you’ll be an outpatient and won't need to stay overnight. Before your gastroscopy, you’ll be given information about what is involved and how to prepare for it.

Before coming to hospital

The information you receive will tell you if you can continue with any regular medicines you’re taking, or if you should stop them for a short while before your procedure. It’s important to follow any advice you’re given. If you don’t, it may not be possible to perform the procedure.

If you’re taking certain medicines (called proton pump inhibitors) that reduce your stomach acid, you may be asked to stop them two weeks beforehand. This is because they might stop your doctor getting a true picture of whether or not there are problems in your gullet or stomach.

It’s particularly important to let your doctor or the hospital team know if you’re taking anticoagulant or antiplatelet medicines (medicines that prevent your blood clotting). These include heparin, aspirin, clopidogrel, warfarin and new medicines such as dabigatran and rivaroxaban. Your doctor will tell you if you should continue taking them – this might depend on which medicine you take. If you continue to take medicines that should be stopped, you may still be able to have a gastroscopy. But you probably won’t be able to have a biopsy or a treatment procedure

You should arrange for someone to take you home, and preferably stay with you for 24 hours afterwards.

On the day

Your stomach must be completely empty during the test, so you’ll probably be asked not to eat or drink anything for six hours before your gastroscopy. However, it’s important to follow your doctor’s advice.

Tell your doctor about any medicines you’re taking, whether they’ve been prescribed or you’ve bought them over the counter.

Your doctor will discuss with you what will happen before, during and after your procedure, and any discomfort you might have. They’ll ask if you wish to have a local anaesthetic or sedation or both. The local anaesthetic is a spray that numbs your throat area. The sedative will make you drowsy, and is given as an injection at the start of the procedure.

Ask your doctor to explain the pros and cons of each type of anaesthesia. For instance, you may be more comfortable with a sedative, but you’ll need to have someone to take you home and keep an eye on you afterwards. If you choose to have the local anaesthetic spray, it may feel a little more uncomfortable at the time, but you won’t be drowsy afterwards.

This discussion with your doctor is your chance to ask questions so that you understand what will happen. Once you understand the procedure and if you agree to have it, your doctor may ask you to sign a consent form.

What happens during a gastroscopy?

A gastroscopy usually only takes five to 10 minutes, though occasionally it may be longer. The procedure will be carried out by a doctor or a specialist nurse.

Your nurse will ask you to take off your shirt or top and put on a hospital gown. They’ll also ask you to remove any dentures or dental plates and your glasses. If you wear contact lenses, you can leave them in.

If you’re having a local anaesthetic, the doctor will spray your throat just before the procedure. If you're having a sedative, this is given through a fine tube (cannula) into a vein in your arm. While you’re sedated, your nurse will monitor your heart rate and the amount of oxygen in your blood through a sensor attached to your finger.

You’ll be asked to lie on your left side. Your doctor will place a guard into your mouth to protect your teeth. They’ll then pass the gastroscope through the opening of the guard into your mouth, until it rests on your tongue at the back of your throat. You’ll then be asked to swallow to allow the gastroscope to pass into your oesophagus and down towards your stomach. This part of the procedure may be uncomfortable for about 20 seconds, and it’s usual to gag once or twice. The discomfort usually soon passes.

To help with the examination, a nurse may use a suction tube to remove any excess saliva from your mouth. Your doctor will also inflate your stomach with air through the gastroscope. This makes it easier to examine the lining of your stomach.

Your doctor will look at images from the gastroscope on a monitor to examine the lining of your oesophagus, stomach and duodenum.

If necessary, your doctor can use the gastroscope to take a biopsy (a small sample of tissue). The samples will be sent to a laboratory for testing.

Some treatments can be carried out through the gastroscope. For more information, see our FAQ below: Can my doctor treat my condition during a gastroscopy?

An image showing where a gastroscope is passed

What to expect after a gastroscopy

After your gastroscopy, you’ll need to rest in a recovery area until the effects of the sedative have passed. You’ll be able to go home when you feel ready, usually after 30 minutes to an hour. Someone else should drive you home.

If you had a local anaesthetic throat spray, you won’t be able to eat or drink until it wears off in about an hour. After that you can eat normally.

Before you leave the hospital, you’ll be given advice about your recovery, and what to do if you have any problems. It’s OK to ask questions if you have any concerns.

Your doctor or specialist nurse may discuss the general findings of the gastroscopy with you before you leave. You may find it best to have a friend or family member there as well, because having a sedative can affect your memory.

Ask your doctor how and when you’ll get your results. You may get a date for a follow-up appointment to discuss the findings in more detail. If biopsies were taken, this follow-up appointment will be planned for when the biopsy results are ready (usually within two weeks). Or your results will be sent in a letter to your GP (and you may get a copy of this letter).

Recovering from a gastroscopy

After your gastroscopy, you may have a slightly sore throat when the local anaesthetic wears off. This can last for one or two days. You can eat and drink as normal once the anaesthetic wears off – about an hour after your gastroscopy.

If you’ve had a sedative, you must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards. It’s best to have a friend or relative stay with you for the first 24 hours, while you rest.

Most people have no problems after a gastroscopy, but you should seek medical attention immediately if you:

  • cough up or vomit blood (which may look like coffee grounds)
  • have blood in your poo (faeces) or odd-coloured faeces
  • have severe pain in your abdomen (tummy) or pain that gets worse
  • have a raised temperature
  • have problems breathing

If you have these symptoms, tell the doctor you see that you have recently had a gastroscopy.

What are the alternatives to a gastroscopy?

The alternative to a gastroscopy is a test called a barium swallow and meal. This involves drinking a special liquid which coats the inside of your oesophagus and stomach and shows up on X-rays. You can find out more from our information on barium swallow and meal.

However, unlike a gastroscopy, a barium swallow and meal doesn’t allow your doctor to take a sample of any abnormal tissue they see.

You can ask your doctor whether this may be an option for you.

What are the risks of having a gastroscopy?

As with every procedure, there are some risks associated with having a gastroscopy.


These are the unwanted but mostly temporary effects you may get after having the procedure.

After having a gastroscopy, you may have a sore throat or stomach discomfort for a few hours. You may feel bloated, but this usually passes quite quickly.


This is when problems occur during or after the procedure. Complications of gastroscopy are very uncommon – the vast majority of patients have no problems at all.

When complications do happen, they may include the following.

  • A reaction to the sedative, such as difficulty in breathing or heart problems. This is the most likely complication.
  • Bleeding, perhaps from where a biopsy is taken or a polyp removed. It’s possible that you may need an operation to stop the bleeding.
  • Damage or tears (perforation) to your throat, oesophagus, stomach or duodenum. This is rare, but if it this happens, you may need an operation to repair the damage.

Complications are more likely if gastroscopy includes a treatment procedure. See our FAQ below: Can my doctor treat my condition during a gastroscopy?

Ask your doctor how these risks might apply to you in your particular circumstances.

Frequently asked questions

  • It’s quite natural to be concerned about gagging, choking, or being unable to swallow when having a gastroscopy. But try not to worry – local anaesthesia and sedation can help you to relax and prevent this.

    You’ll need to swallow the gastroscope to let it move down into your stomach. But you’ll be able to breathe normally throughout the procedure because your airway won’t be blocked.

    Your doctor will offer to spray a local anaesthetic on to the back of your throat, to numb your throat and mouth area. This will help to reduce any gagging that the gastroscope may cause as it passes down your throat. But be aware that most people will gag a few times. You’ll usually be offered a sedative as well, to help you relax and make you drowsy.

    No one will force you to carry on with the gastroscopy if you decide that you really can’t tolerate it. But remember that the procedure usually only lasts between five and 10 minutes. And your medical team will do all they can to help you through it.

  • A gastroscopy is usually done to investigate the cause of your gastrointestinal symptoms and give a diagnosis. However, one of the benefits of gastroscopy is that it can also be used to give certain treatments.

    Treatments you may have during a gastroscopy include the following.

    • Removal of a swallowed object (foreign body) that has become stuck.
    • Stopping bleeding from damaged tissue such as an ulcer. Instruments passed through the gastroscope can stop bleeding in various ways. These include applying clips, heat-sealing, and injecting the tissue with a substance that stops it bleeding (sclerotherapy).
    • Stretching (dilating) narrowed areas of your oesophagus, stomach or duodenum, with a small balloon passed through the gastroscope.
    • Removing polyps (small benign growths) or other growths your doctor is concerned about. This is done using special instruments passed inside the gastroscope.

  • Yes, if you need to. Doctors usually try to avoid doing any procedures during pregnancy, especially during the first three months when the baby is developing. But in some circumstances your doctor may recommend you have a gastroscopy even though you’re pregnant. They’ll only do this if they think the benefits outweigh any potential harms to you and your unborn baby.

    There isn’t enough evidence yet to know for sure if a gastroscopy could harm your unborn baby. But if you have a gastroscopy during pregnancy, your doctor will take precautions to keep you and the baby safe. They’ll do the procedure as quickly as possible, and give you the minimum amount of sedative medicine. You’ll lie in such a way that the baby doesn’t press on your major abdominal blood vessel, so reducing blood supply to the placenta. And the baby’s heart rate may be monitored.

    If your doctor recommends you have a gastroscopy, ask them to explain why they believe this is the best option for you. It is your choice whether or not to go ahead after discussion with your doctor.

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  • Reviewed by Dr Kristina Routh, Freelance Health Editor, November 2018
    Expert reviewer, Dr Ian Arnott, Consultant Gastroenterologist
    Next review due November 2021

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