A gastroscopy is a test to examine the upper part of your digestive system. This is called the upper gastrointestinal tract. It includes your:

  • food pipe (oesophagus)
  • stomach
  • the first part of the small intestine (small bowel)

A specially trained doctor or nurse passes a thin, flexible tube through your mouth and down your food pipe. This tube has a light on the end.

The tube does not get in the way of your breathing at any time. It passes down your food pipe and not your windpipe. When we put in the tube, it passes the back of your throat. This makes you gag or retch, but that improves when the tube reaches your food pipe.

Sometimes, we take small samples of tissue and send them to be checked in a laboratory. This is called having a biopsy. The samples that we take are about the size of a match head and do not cause you any pain but you might feel a slight tugging sensation.

A gastroscopy is a quick procedure. It takes about 5 to 15 minutes.

If you need treatment during the gastroscopy, your doctor or specialist nurse tells you whether the procedure will take longer. They explain what to expect.

Why you might have a gastroscopy

A gastroscopy can help to monitor a long-term condition. It can also help to find the cause of your digestive symptoms, such as:

  • pain in your upper tummy (abdomen)
  • difficulty swallowing
  • indigestion that keeps happening
  • being sick (vomiting)
  • bleeding
  • heartburn

A gastroscopy can help to diagnose:

  • ulcers
  • inflammation
  • infection
  • helicobacter pylori (bacteria that can cause ulcers, a condition called gastritis when your stomach lining is inflamed and stomach cancer)
  • coeliac disease (when you cannot digest a protein called gluten)
  • cancer

We can also do a gastroscopy to check a digestive condition that we have previously diagnosed.

Risks of having a gastroscopy

A gastroscopy is a safe procedure and serious complications are rare.

Sometimes, the tube used during the test can damage the lining of the food pipe, stomach or intestine. This can cause:

  • bleeding
  • infection
  • rarely, a tear in the food pipe, stomach or intestine. If this happens, you might need to have a blood transfusion (where we give you blood from someone else), come into hospital or have surgery to treat the problem

There is also a small chance of damage to your teeth. This can happen if you bite hard on the mouth piece needed to keep your mouth open during the procedure. It is very rare.

Your doctor or specialist nurse discusses the possible complications with you before you sign the consent form.

Other options to a gastroscopy

Another option is to have a barium meal. This is when you have an X-ray after drinking some barium liquid (a white liquid that shows on X-rays).

As X-rays cannot go through barium, the outline of your stomach shows on the X-ray picture.

A barium test involves radiation and is less accurate than a gastroscopy. We cannot remove samples (biopsies) of the gut or polyps (small growths) during a barium meal. This means that you might still need a gastroscopy. You might also still need a gastroscopy if we find anything unusual.

We want to involve you in decisions about your care and treatment. If you decide to have a gastroscopy, we ask you to sign a consent form. This says that you agree to have the treatment and understand what it involves.

If you would like more information about our consent process, please speak to a member of staff caring for you.

Resource number: 2044/VER6
Last reviewed: July 2021
Next review: July 2024

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If you need to change or cancel your appointment, please call 020 7188 8887.

Questions, problems or concerns

Please contact the endoscopy unit staff for advice from Monday to Saturday, 9am to 5pm.

Nurse in charge: 020 7188 7188 ext 54059

St Thomas' reception desk: 020 7188 7188 ext 54046

In an emergency, out of hours

Out of hours means 6pm until 8am the next day and on Saturday or Sunday.

Phone 020 7188 7188 and ask to be put through to the on-call gastroenterology registrar (through an application called RotaWatch).

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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