How a gastroscopy is carried out

About gastroscopy

A gastroscopy is also known as an upper gastrointestinal endoscopy. It is performed using a narrow, flexible, telescopic camera called a gastroscope. The gastroscope is swallowed and passed down your oesophagus into your stomach and then into the duodenum.

A gastroscopy can help find out what is causing symptoms such as:

  • indigestion
  • heartburn
  • repeated vomiting or vomiting blood
  • difficulty swallowing
  • long-term abdominal (tummy) pain
  • weight loss
  • anaemia

It's also used to check for certain gastrointestinal conditions such as:

  • coeliac disease
  • ulcers
  • Barrett's oesophagus
  • early signs of cancer

A gastroscopy can be used to see if there are any growths or ulcers in your oesophagus, stomach or duodenum, and can be used to remove any blockages.

What are the alternatives?

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

Preparing for a gastroscopy

Your doctor will explain how to prepare for your procedure.

Let your doctor know if you are taking anticoagulant medicines (medicines that prevent your blood clotting) such as heparin, clopidogrel or warfarin.

Gastroscopy is usually done as a day-case procedure in hospital. This means that you won't need to stay overnight.

Your stomach needs to be completely empty so your doctor can see the lining of your stomach and duodenum clearly. You will be asked to follow fasting instructions. Typically, you must not eat or drink for six to eight hours before your gastroscopy. However, it’s important to follow your doctor’s advice.

Gastroscopy may be done under local anaesthesia, which is usually given as a throat spray. This blocks pain from your throat, but you will stay awake during the procedure. You will usually be offered a sedative to help you relax, which is given as an injection at the start of the procedure. Sedative medicines used include diazepam and although you will still be awake 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, and 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 give your consent for the procedure to go ahead, which you may be asked to do by signing a consent form.

What happens during a gastroscopy

The procedure usually takes between five and 30 minutes.

Your nurse will ask you to take off your shirt or top and put on a hospital gown. He or she will also ask you to remove dentures or dental plates, contact lenses, glasses and jewellery.

If you're having a sedative, this is usually given through a fine tube (cannula) into a vein in your arm. Sedatives can sometimes affect your breathing. So while you're sedated, your doctor will monitor the amount of oxygen in your blood through a sensor attached to your finger and he or she may give you extra oxygen to breathe.

You will be asked to lie on your left side with your head bent slightly forward. Your doctor will place a mouth guard over your teeth before carefully putting the gastroscope through the opening in the guard into your mouth. Your doctor will ask you to swallow to allow the gastroscope to pass into your oesophagus and down towards your stomach.

A nurse may use a suction tube to remove excess saliva from your mouth during the procedure.

Your doctor will pump air through the gastroscope and into your stomach to expand it. This makes your stomach lining easier to see. The camera lens at the end of the gastroscope sends images from the inside of your body to a monitor. Your doctor will look at these images to examine the lining of your oesophagus, stomach and duodenum.

If necessary, your doctor will take a biopsy (a small sample of tissue) or remove small growths of tissue called polyps. This is done using special instruments passed inside the gastroscope. 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.

What to expect afterwards

You will need to rest until the effects of the sedative have passed. You will usually be able to go home when you feel ready. 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 may take several hours before the feeling comes back into your mouth and throat. Don’t try to eat or drink until you can swallow normally. Once you’re able to swallow, you can usually return to your normal diet. However, don’t drink hot drinks until the local anaesthetic has fully worn off.

Your doctor may discuss the general findings of the gastroscopy with you before you leave the hospital, or you may be given a date for a follow-up appointment. If you have a biopsy or polyps removed, your test results will be ready several days later.

Recovering from a gastroscopy

If you need pain relief, you can take over-the-counter medicines, such as paracetamol or ibuprofen. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.

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 and please contact your motor insurer so that you're aware of their recommendations.

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

  • cough up or vomit blood
  • have blood in your faeces
  • have abdominal pain or shoulder pain that gradually gets worse, or is more severe than any pain that you had before the test

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 numb throat for a few hours
  • have a sore throat or stomach pain for a few hours
  • feel bloated, but this usually passes quite quickly


This is when problems occur during or after the procedure. Most people aren't affected.

Specific complications of gastroscopy are uncommon, but include the following.

  • Bleeding, particularly if a biopsy has been taken.
  • Damage or tears to your oesophagus, stomach or duodenum, particularly if a biopsy has been taken or a polyp has been removed.
  • A reaction to the sedative, such as a skin rash, difficulty in breathing or heart problems.

How soon after my gastroscopy can I eat or drink?


If you haven't had a local anaesthetic, you can eat and drink as soon as you feel ready. If your doctor used a local anaesthetic spray to numb your throat, you will need to wait until you can swallow normally. You shouldn't drink hot drinks until the anaesthetic has worn off completely.


Your doctor will usually offer to spray a local anaesthetic on to the back of your throat to numb your throat during the procedure. The effects of the local anaesthetic spray will last for a while after the procedure has finished. They can take between 20 minutes and two hours to wear off.

As your mouth and throat will be numb, you will need to wait until you can swallow normally before you can eat and drink. Start with sips of cold water. If you can swallow the water easily without coughing and it feels cold, then you are ready to start eating and drinking. Don't have any hot drinks until the anaesthetic has worn off completely as you could burn yourself without realising.

Will I gag during my gastroscopy?


Sometimes, as the gastroscope passes down your throat, it may cause you to gag. However, local anaesthetic and sedation can help to prevent this. You will be able to breath normally throughout the procedure.


During a gastroscopy, you will need to swallow the gastroscope to help it move down towards your stomach.

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 may be caused by the gastroscope as it passes down your throat. You will usually be offered a sedative as well, to help you relax. The sedative will relax your throat and also help prevent gagging. Most people swallow the gastroscope without any problems as it's very thin – between 5 and 11mm in diameter. If you do start to gag, your doctor or nurse will usually ask you to breathe deeply, as this can stop you retching.

Will my doctor be able to treat my condition during the gastroscopy?


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


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 he or she 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), he or she will usually remove them during the procedure. This is done using special instruments passed inside the gastroscope.

If you have bleeding from damaged tissue, a gastroscopy may be used to allow your doctor 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.