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Diagnostic endoscopy of the stomach

Page last reviewed: 13/07/2011

A diagnostic gastroscopy is a general term to describe a diagnosis that is made inside the upper gastrointestinal tract using a piece of equipment called an endoscope.

Diagnostic gastroscopy is also known as diagnostic endoscopy of the stomach and oesophagogastroduodenoscopy (OGD).

The gastrointestinal tract

The gastrointestinal (GI) tract is the medical term for the digestive system. The upper GI tract consists of:

  • the mouth
  • the oesophagus (also known as the gullet) - the tube that runs from the mouth, down the throat and into the stomach
  • the stomach
  • the duodenum - the first section of the small intestine

What is an endoscope?

An endoscope is a thin, flexible tube that is about the width of your little finger. The endoscope has a light and a camera on one end. The camera is used to relay images of the inside of your body to a television monitor.

A diagnostic gastroscopy is often used to investigate symptoms of the upper GI tract, such as:

  • difficulties and/or pain when swallowing (dysphagia)
  • persistent abdominal pain

A diagnostic gastroscopy is a very common procedure.


A diagnostic gastroscopy is usually a very safe procedure. Serious complications are rare, occurring in about one in every 1,000 cases.

Possible complications of a diagnostic gastroscopy include:

  • infection
  • bleeding
  • perforation of the GI tract

Alternatives/Additional tests to upper GI endoscopy

Barium swallow or meal

This involves drinking a white liquid containing barium sulphate. It coats your upper GI tract so that it shows up on an X-ray. There are fewer risks with a barium swallow than with an upper GI endoscopy, but it is not as successful in spotting problems because the doctor cannot do a biopsy.

Acidity test

A thin tube is passed through your nose and into your oesophagus, where it is left for 24 hours. The tube measures how acidic your oesophagus is. The results are displayed electronically.

Radiolabeled technetium

Compounds containing radioactive atoms are introduced into the body to show how an organ is working.

Page last reviewed: 13/07/2011

A diagnostic gastroscopy is usually recommended if your symptoms suggest that you have a condition that affects your upper gastrointestinal (GI) tract.

Symptoms that are often investigated using a diagnostic gastroscopy include:

  • difficulties and/or pain when swallowing (dysphagia)
  • persistent abdominal pain
  • persistent nausea and vomiting
  • unexplained weight loss

A diagnostic gastroscopy can also be used if your GP suspects that you have bleeding inside your GI tract. Persistent bleeding can significantly reduce the number of red blood cells in your body. This is known as anaemia.

Symptoms of anaemia include:

  • fatigue
  • breathlessness (dyspnoea)
  • pale skin
  • irregular heart beats

In some cases, bleeding inside the GI tract can be sudden and massive, and cause symptoms such as:

  • vomiting blood - the blood can appear bright red or have a darker, grainy appearance similar to coffee granules
  • passing stools (faeces) - which are very dark in colour or 'tar-like'
  • a sudden, sharp pain in your abdomen (stomach) that gets steadily worse

These symptoms usually require immediate investigation with a diagnostic gastroscopy.

Confirming a diagnosis

A diagnostic gastroscopy is also used to help confirm (or rule out) the suspected diagnosis of certain GI conditions, such as those listed below.

  • Peptic ulcer (also known as stomach ulcer) - open sores that develop on the lining of your stomach.
  • Gastro-oesophageal reflux disease (GORD) - a condition where stomach acid leaks back up into the oesophagus.
  • Barrett's oesophagus - a condition where abnormal cells develop on the lining of the oesophagus.
  • Portal hypertension - a condition where the blood pressure inside the liver is abnormally high. This leads to the development of abnormally swollen veins (varices) on the lining of the stomach and oesophagus.
  • Cancers of the upper GI tract, such as stomach cancer and oesophageal cancer - the endoscope can be used to remove samples of suspected cancerous tissue for testing, which is known as a biopsy.

Page last reviewed: 13/07/2011

Diagnostic gastroscopy is a non-invasive procedure, which means that it does not involve making major incisions (cuts) into the body. Therefore, it is usually suitable for most people, even if their health is not particularly good.

However, there may be a few circumstances where a diagnostic gastroscopy is not recommended. These include:

  • if you have an unhealed perforation inside your GI tract
  • if you have recently had a heart attack
  • if you have recently had head or neck surgery (in this situation, it is usually recommended that you wait until you have fully recovered from the effects of the surgery).

Page last reviewed: 13/07/2011

Preparing for a diagnostic gastroscopy

You will usually receive written information about how to prepare for a diagnostic gastroscopy, along with your appointment letter. If there is anything that you feel needs to be clarified, call the hospital.

If you are referred for an endoscopy, you will need to stop taking any prescribed medicines for dyspepsia (indigestion) at least two weeks beforehand. This is because they can mask some of the problems that could show up. You can continue to take antacids up until your endoscopy.

You will be asked not to eat or drink anything for six hours before having your endoscopy. It is important that your stomach is empty so that the person who is performing the endoscopy can see the whole area clearly.

If you wish, you can choose to have the procedure carried out under sedation (see below) in order to help prevent food or fluid from passing into your lungs.


A diagnostic gastroscopy is not a particularly painful procedure, although some people may find it slightly uncomfortable. Therefore, you can choose the type of anaesthetic that is used during the procedure:

  • local anaesthetic spray is used to numb the back of your throat
  • sedation makes you very drowsy so that you have little or no awareness of the gastroscopy being carried out.

If you choose to have sedation, you will need to arrange for someone to bring you home after the procedure and to stay with you for at least 12 hours afterwards.

Even if you feel very alert, the sedative can stay in your blood for around 24 hours. You may have further episodes of drowsiness during this period. Therefore, during this time, do not:

  • drive a vehicle
  • operate heavy machinery
  • drink any alcohol

If you choose to have a local anaesthetic, you can leave hospital as soon as the procedure has been completed, and you can resume your normal activities within 1-2 hours.

The procedure

A diagnostic gastroscopy is usually done at the endoscopy unit at your local hospital (although some larger GP surgeries may also offer endoscopic services).

A diagnostic gastroscopy is usually performed on an out-patient basis, which means that you will not have to stay overnight in hospital. If, however, you choose to have a sedative and you live alone, you may have to stay in overnight.

A diagnostic gastroscopy can be performed by:

  • a gastroenterologist (a specialist in disorders of the digestive tract)
  • a surgeon
  • a endoscopist (a doctor who has received special training in using an endoscope)
  • a clinical nurse who has received specialist training in endoscopies

A nurse will talk you through the procedure to make sure that you understand why you are having it. They will ask you questions to ensure that you are properly prepared for the procedure and that you understand any associated risks. You will also be asked to sign a consent form.

At the start of the procedure, you will be asked to lie on a bed or X-ray couch, on your left-hand side. This allows the endoscopist to pass the scope more easily into your stomach. You will be given a plastic mouth guard to stop your teeth from being damaged by the endoscope as it goes down, and to stop you biting on it.

If you choose to have your gastroscopy carried out under sedation, the sedative will be injected into your arm. The medication will make you relaxed and drowsy, but you will be awake enough to follow any instructions.

If you choose to have a local anaesthetic, the back of your throat may be sprayed to numb it, or you may be given an anaesthetic lozenge to suck on.

Once the sedative or throat spray has worked, the doctor will put the endoscope in your mouth and you will be asked to swallow the first part of the tube. It may be a little uncomfortable to swallow, but there will be plenty of room for you to breathe around the scope and through your nose.

The doctor will gently and carefully feed the tube down into your stomach, and a short way beyond your stomach and into your intestine. You will be asked to breathe through your nose.

Once the endoscope is in your stomach, air is blown into your stomach to allow the endoscopist to see any patches of redness, holes, lumps, blockages, or other abnormalities on a television monitor.

If any areas of abnormality are detected, a biopsy will be taken (a tissue sample from the abnormal-looking area) to send to the laboratory for closer inspection under a microscope. During the biopsy, you will not feel anything.

Once any necessary samples have been taken, the doctor will remove the endoscope by pulling it back out of your gullet and through your mouth.

After the test, you will need to rest for a while. If you have had a sedative, you may not remember much, if anything, about the test after you come round.


If you have had a local anaesthetic, your doctor should be able to discuss the results and implications of the gastroscopy before you leave hospital. However, if you have had a biopsy, you will usually have to wait for seven days to get the results.

If you were sedated, you will probably still be too drowsy to understand any information. A further appointment will be made so that you can discuss the results with the doctor. Alternatively, the results of the gastroscopy may be sent to your GP.

Page last reviewed: 13/07/2011

A diagnostic gastroscopy has an excellent safety record. Serious complications are rare, occurring in 1 in 1,000 cases.

Complications of a diagnostic gastroscopy include:

  • adverse effects of sedation
  • infection
  • perforation
  • bleeding


Sedation is usually a safe procedure, although it can occasionally cause complications. Complications associated with sedation can range from mild to serious, including:

  • nausea
  • vomiting
  • a burning sensation at the site of the injection
  • small particles of food that fall into the lungs and trigger an infection (aspiration pneumonia)
  • irregular heartbeat
  • breathing difficulties
  • stroke

Very rarely, complications arising from sedation can cause death. This is very unlikely, occurring in 1 out of 25,000 cases.


Occasionally, during a gastroscopy, bacteria can enter the bloodstream through small tears and incisions (cuts) in tissue that occurred during the procedure. In most cases, the bacteria do not cause serious problems and they are killed by the immune system.

However, in rare cases, the bacteria can travel to the heart and infect the heart's lining, muscles and valves. This type of infection is known as endocarditis.

Symptoms of endocarditis include:

  • high temperature (fever) of 38ºC (100.4ºF) or above
  • chills
  • an usual sounding heartbeat (murmur)
  • fatigue
  • night sweats
  • aching muscles and joints

Endocarditis can be treated with antibiotic injections and, in the most serious cases, surgery to repair the heart.

Internal bleeding

Sometimes, the endoscope can inadvertently damage a blood vessel, which results in internal bleeding.

Symptoms of internal bleeding can include:

  • fatigue
  • breathlessness (dyspnoea)
  • pale skin
  • vomiting blood
  • passing stools that are very dark or 'tar-like'

The source of internal bleeding can usually be repaired using a further gastroscopy, in the same way that a bleeding varices or an ulcer is repaired. Blood transfusions may also be needed to replace lost blood.


During a gastroscopy, there is a small risk that the endoscope will perforate the tissue inside your oesophagus, abdomen and/or your chest.

Symptoms arising from a perforation include:

  • neck pain
  • pain when swallowing
  • abdominal pain
  • high fever
  • breathing difficulties

If your symptoms suggest that the perforation is not severe, it can normally be left to heal by itself. You may be given antibiotics to prevent an infection at the site of the perforation.

However, if your symptoms suggest that the perforation is more extensive, such as severe pain that does not respond to painkillers, then surgery may be required to repair it.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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