Expert reviewer, Dr Alistair McNair, Consultant Gastroenterologist
Next review due May 2019

A gastroscopy is a procedure that allows a doctor to look inside your oesophagus (the tube that connects your mouth to your stomach), your stomach and part of your small intestine (duodenum).

You will meet the doctor carrying out your procedure to discuss your care. It may differ from what is described here as it will be designed to meet your individual needs.

Preparing for a gastroscopy

Your doctor will explain how to prepare for your procedure.

Your doctor will ask if you are taking anticoagulant medicines (medicines that prevent your blood clotting). These include heparin, aspirin, clopidogrel, warfarin and new medicines such as dabigatran and rivaroxaban. These may cause complications during the procedure. If you normally take other medicines, ask your doctor if you should still take them.

Gastroscopy is usually done as a day-case procedure in hospital. This means that you will be an outpatient and won't need to stay overnight. It may be possible to choose where you have your procedure. You might be told about units with a JAG accreditation, if this is an option for you. This comes from The Joint Advisory Group on Gastrointestinal Endoscopy (JAG), which is part of the Royal College of Physicians. If you’d like to find out more, visit their website for further information.

Your stomach must be completely empty during the test, so the hospital will give you fasting instructions. Typically, you must not eat or drink for four hours before your gastroscopy. However, it’s important to follow your doctor’s advice.

Before the procedure you will be given a choice of a local anaesthetic or a sedative (though you may have both). The local anaesthetic is a spray that numbs your throat area and reduces gagging. The sedative will help you relax; this is given as an injection at the start of the procedure. After you have swallowed the gastroscope (sometimes called an endoscope), you can receive additional sedation if necessary. Because of the way the sedatives work, you’ll be awake and you may remember very little about the procedure.

Your doctor will discuss with you what will happen before, during and after your procedure, and any pain you might have. This is your opportunity to understand what will happen. You can help yourself by preparing questions to ask about the risks, benefits and any alternatives to the procedure. This will help you to be informed, so you can sign a consent form for the procedure to go ahead.

What are the alternatives to a gastroscopy?

Depending on your symptoms, it may be possible to diagnose your condition using different or additional tests, such as an X-ray called a barium swallow, a CT scan, MRI scan or ultrasound scan.

What happens during a gastroscopy?

The procedure usually takes five to 10 minutes, though occasionally may be longer. The procedure will be carried out by a doctor, or sometimes a trained nurse.

Your nurse will ask you to take off your shirt or top and put on a hospital gown. They will also ask you to remove dentures or dental plates, contact lenses or glasses. There will be a series of brief checks to make sure the procedure is OK to go ahead.

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. Sedatives can sometimes affect your breathing, so while you are sedated your nurse will monitor your heart rate and the amount of oxygen in your blood through a sensor attached to your finger. There will be extra oxygen on hand, which the nurse can give you if you need it.

You will lie on your left side. Your doctor will place a guard into your mouth to protect your teeth. They will then carefully pass an instrument called a gastroscope through the opening of the guard into your mouth, until it rests on your tongue at the back of your throat. They will then ask you to swallow to allow the gastroscope to pass into your oesophagus and down towards your stomach.

To help with the examination, a nurse may use a suction tube to remove 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.

A camera lens at the tip of the gastroscope sends video images to a monitor. Your doctor will look at these images to examine the lining of your oesophagus, stomach and duodenum.

If necessary, your doctor can use the gastroscope to take biopsies (a small sample of tissue) or remove small growths of tissue called polyps. The samples will be sent to a laboratory for testing. Some other procedures can be carried out through the gastroscope, including stretching narrowed areas of your oesophagus, stomach or duodenum, and treating blood vessels or ulcers using injections or heat.

An image showing where a gastroscope is passed

What to expect afterwards

You will need to rest in a recovery area until the effects of the sedative have passed. You will be able to go home when you feel ready, usually between 30 minutes and one hour. You will need to arrange for someone to drive you home. You should have a friend or relative stay with you for the first 24 hours.

After a local anaesthetic, it usually takes around an hour before the feeling comes back into your mouth and throat. The team looking after you will offer you food and drink once the anaesthetic has worn off, and advise you on eating and drinking at home.

Before you leave the hospital, your doctor may discuss the general findings of the gastroscopy. They may also explain care plans or give instructions for your recovery. You will probably get a date for a follow-up appointment to discuss the findings in more detail. If biopsies were taken or you had polyps removed, this follow-up will be once the biopsy results are ready. Any results will also be sent to your GP.

Recovering from a gastroscopy

You shouldn’t need to take any pain relief after the procedure, although you may have a slightly sore throat when the local anaesthetic wears off.

Sedation temporarily affects your co-ordination and reasoning skills, so you must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards. If you’re in any doubt about driving, always follow your doctor's advice.

Most people have no problems after a gastroscopy, but you should see your doctor immediately if you:

  • feel very bloated
  • cough up or vomit blood
  • have blood in your faeces, or odd-coloured faeces
  • experience severe pain
  • have a fever
  • have problems breathing

What are the risks?

As with every procedure, there are some risks associated with gastroscopy. We have not included the chance of these happening as they are specific to you and differ for every person. Ask your doctor to explain how these risks apply to you.


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 uncommon, but include the following.

  • A reaction to the sedative, such as difficulty in breathing or heart problems.
  • Bleeding, particularly if a biopsy has been taken.
  • Damage or tears to your throat, oesophagus, stomach or duodenum. This may happen if a biopsy has been taken, a narrowing in your oesophagus has been stretched or a polyp has been removed.
  • Infection.

Frequently asked questions

  • Gagging, choking, or being unable to swallow are common and normal worries to have when having a gastroscopy. However, local anaesthetic and sedation can help you to relax and prevent this. You will be able to breathe normally throughout the procedure.


    During a gastroscopy, you will need to swallow the gastroscope to allow it to move down into your stomach. However, this won’t affect your breathing as it doesn’t block your airway.

    Before the procedure your doctor will offer to spray a local anaesthetic on to the back of your throat, which will numb your throat and mouth area. This will help to prevent any gagging that the gastroscope may cause as it passes down your throat. You will usually be offered a sedative as well, to help you relax.

    The gastroscope is quite narrow – between 8 and 11mm in diameter. If you do start to panic, your doctor or nurse will be able to help you and may ask you to breathe deeply and slowly. Your doctor will not force the gastroscope if you’re resisting it or panicking. Occasionally, your doctor may decide to stop the procedure.

  • Gastroscopy is usually done to investigate the cause of your gastrointestinal symptoms and provide a diagnosis. However, it's sometimes used to give certain treatments.


    The purpose of a gastroscopy is usually to find out what is causing your gastrointestinal symptoms, such as indigestion, repeated vomiting or vomiting blood.

    Your doctor may be able to do this simply by looking at the lining of your gastrointestinal system, or they may take a small sample of tissue (biopsy) during the procedure. These will be sent to a laboratory for testing.

    If your doctor finds any polyps (small growths of tissue), they will usually remove them during the procedure. This is done using special instruments passed inside the gastroscope.

    If you have bleeding from damaged tissue, the doctor may be able to stop the bleeding. This is done by passing instruments through the gastroscope to heat-seal (cauterise) the bleeding blood vessel or inject the tissue with a substance that stops it bleeding.

    Some other procedures can be carried out through the gastroscope, including stretching narrowed areas of your oesophagus, stomach or duodenum, and treating ulcers using injections or heat.

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  • Reviewed by Nick Ridgman, Lead Health Editor, Bupa Health Content Team, May 2016
    Expert reviewer, Dr Alistair McNair, Consultant Gastroenterologist
    Next review due May 2019

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