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Gastroscopy is a test to look inside the gullet (oesophagus), the stomach and the first part of the gut (small intestine) known as the duodenum.

Note: the information below is a general guide only. The arrangements, and the way tests are performed, may vary between different hospitals and areas. Always follow the instructions given by your doctor or local hospital.

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What is a gastroscopy?



A gastroscopy is a test where an operator - a doctor or nurse - looks into the upper part of your gut (the upper gastrointestinal tract).

The upper gut consists of the gullet (oesophagus), the stomach and the first part of the gut (small intestine) known as the duodenum. The operator uses an endoscope to look inside your gut. Therefore, the test is sometimes called endoscopy.

An endoscope is a thin, flexible telescope. It is about as thick as a little finger. The endoscope is passed through the mouth, down the food pipe into the oesophagus and down towards the stomach and duodenum.

The tip of the endoscope contains a light and a tiny video camera so the operator can see inside your gut.

The endoscope also has a side channel down which various instruments can pass. These can be manipulated by the operator. For example, the operator may take a small sample (biopsy) from the inside lining of the stomach by using a thin 'grabbing' instrument which is passed down a side channel.

Why do I need a gastroscopy?

A gastroscopy may be advised if you have symptoms such as:

  • Repeated (recurring) indigestion.

  • Recurring heartburn.

  • Pains in the upper tummy (abdomen).

  • Repeatedly being sick (vomiting).

  • Difficulty swallowing.

  • Other symptoms thought to be coming from the upper gut, stomach or oesophagus.

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What is a gastroscopy looking for?

What happens during a gastroscopy?

Gastroscopy is usually done as an outpatient 'day case'. It is a routine test which is commonly done. Before the test the operator will explain to you what is going to happen and ask you to sign a consent form. The operator may numb the back of your throat by spraying on some local anaesthetic, or give you an anaesthetic lozenge to suck. You may be given a sedative to help you to relax. This is usually given by an injection into a vein in the back of your hand. The sedative can make you drowsy but it does not put you to sleep completely. It is not a general anaesthetic.

You lie on your side on a couch. You are asked to put a plastic mouth guard between your teeth. This works to protect your teeth and stops you biting the endoscope. The operator will then ask you to swallow the first section of the endoscope. Modern endoscopes are quite thin but some people may find this difficult.

The operator then gently pushes it further down your gullet (oesophagus) and into your stomach and the first part of your gut (small intestine) known as your duodenum. The video camera at the tip of the endoscope sends pictures to a screen. The operator watches the screen for abnormalities of the oesophagus, stomach and duodenum. Air is passed down a channel in the endoscope into the stomach to make the stomach lining easier to see. This may cause you to feel bloated and want to belch.

The operator may take one or more small tissue samples (biopsies) of parts of the inside lining of the gut - depending on why the test is done and what they see. This is painless. The biopsy samples are sent to the laboratory for testing and to look at under the microscope. The endoscope is then gently pulled out.

How long does a gastroscopy take?

A gastroscopy usually takes about 10 minutes. However, you should allow at least two hours for the whole appointment. This is to prepare, give time for the sedative to work (if you have one), for the gastroscopy itself and to recover. A gastroscopy may be quite uncomfortable but it does not usually hurt.

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How do you prepare for a gastroscopy

You should receive instructions from the hospital department before your test. The sort of instructions given commonly include:

  • You should avoid eating or drinking for 4-6 hours before the test. The stomach needs to be empty. (Small sips of water may be allowed up to two hours before the test.)

  • If you have a sedative you will need somebody to accompany you home.

  • Advice about medication which may need to be stopped before the test.

What can I expect after a gastroscopy?

Most people are ready to go home after resting for half an hour or so.

If you have had a sedative - you may take a bit longer to be ready to go home. The sedative will normally make you feel quite pleasant and relaxed. However, you should not drive, operate machinery or drink alcohol for 24 hours after having the sedative. You will need somebody to accompany you home and to stay with you for 24 hours until the effects have fully worn off. Most people are able to resume normal activities after 24 hours.

The operator writes a report and sends it to the doctor who requested the gastroscopy. The result from any sample (biopsy) may take a few days, which can delay the report being sent. The operator may also tell you what he/she saw before you leave. However, if you have had a sedative you may not remember afterwards what you were told. Therefore, you may wish to have a relative or close friend with you who may be able to help remember what was said.

Is gastroscopy reliable?

Gastroscopy is a good test for seeing abnormalities in the upper gut. However, it is not foolproof. For example, gastroscopy may not detect a small number of cases of early ulcers or early cancer. Sometimes a repeat gastroscopy may be advised if symptoms persist or become worse, even if a previous gastroscopy was reported as normal.

Is a gastroscopy dangerous?

Most gastroscopies are done without any problem. Some people have a mildly sore throat for a day or so afterwards. You may feel tired or sleepy for several hours if you have a sedative. There is a slightly increased risk of developing a chest infection or pneumonia following a gastroscopy.

Occasionally, the endoscope causes some damage to the gut. This may cause bleeding, infection and rarely a hole (perforation). If any of the following occur within 48 hours after a gastroscopy, consult a doctor immediately:

  • Tummy (abdominal) pain. (In particular, if it becomes gradually worse, and is different from or more intense than any 'usual' indigestion pains or heartburn that you may have.)

  • Raised temperature (fever).

  • Difficulty breathing.

  • Bringing up (vomiting) blood.

A small number of people have a heart attack or stroke during, or soon after, a gastroscopy. These tend to be older people who are already in poor health. These serious complications are rare in most people who are otherwise reasonably healthy.

Rarely, some people have an allergic reaction to the sedation.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • Next review due: 27 Mar 2028
  • 29 Mar 2023 | Latest version

    Last updated by

    Dr Rosalyn Adleman, MRCGP

    Peer reviewed by

    Dr Rachel Hudson, MRCGP
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