Endoscopy – Gastroscopy


Endoscopy – Gastroscopy


A gastroscopy is a medical procedure where a thin, flexible tube called an endoscope is used to look inside the stomach.

The procedure is also sometimes referred to as an upper endoscopy.

An endoscope has a light and a camera at one end. The camera sends images of the inside of your body to a television monitor.

This topic focuses on gastroscopies that are used to examine and/or treat conditions affecting the upper section of the digestive system, such as the stomach and gullet.

When a gastroscopy is needed 

A gastroscopy may be recommended if you have symptoms that suggest a stomach problem. This could be difficulty swallowing (dysphagia) or persistent abdominal pain. The procedure can be used to help diagnose the underlying cause of your symptoms.

A gastroscopy can also be used to treat various gut-related problems. Tiny tools can be passed down the endoscope to:

repair bleeding ulcers and veins

widen a blocked oesophagus (the tube through which food passes to the stomach)

provide nutrition if you're unable to eat food in the normal way

remove non-cancerous growths (polyps) or early-stage cancerous tumours

The procedure

A gastroscopy can take about 15 minutes, depending on why it's being used.

It's usually carried out as an outpatient procedure, which means that you won't have to spend the night in hospital.

The procedure is often carried out under sedation. You won't be asleep but you'll be very drowsy and have little awareness about what's happening. Alternatively, your throat can be numbed with a local anaesthetic spray.

The doctor carrying out the procedure will place the endoscope in the back of your mouth and ask you to swallow the first part of the tube. It will then be guided down your oesophagus and into your stomach.


A gastroscopy is a very safe procedure and serious complications, such internal bleeding, are rare, occurring in less than 1 in 1,000 cases.

Why a gastroscopy is used 

A gastroscopy can be used to check symptoms or confirm a diagnosis (diagnostic gastroscopy), or it can be used to treat a condition (therapeutic gastroscopy).

Checking symptoms

A diagnostic gastroscopy may be recommended if you have symptoms that suggest a problem with your stomach, which may also affect your oesophagus (gullet) or the first section of your small intestine (duodenum).

Symptoms that are often investigated include:

difficulties swallowing or pain when swallowing (dysphagia)

persistent abdominal pain

persistent nausea and vomiting

unexplained weight loss

A diagnostic gastroscopy can also be used if bleeding inside your stomach or small intestine is suspected. Persistent bleeding can significantly reduce the number of red blood cells in your body (anaemia).

Symptoms of anaemia include:

feeling tired all the time


pale skin

irregular heartbeats

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

vomiting blood

passing stools (faeces) that are very dark or ‘tar-like’

a sudden, sharp pain in your abdomen 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) suspected conditions, such as those listed below.

Stomach ulcer (also known as peptic ulcer disease) - open sores that develop on the lining of the stomach and small intestine.

Gastro-oesophageal reflux disease (GORD) - a condition where stomach acid leaks back up into the oesophagus.

Barrett's oesophagus - where abnormal cells develop on the lining of the oesophagus.

Portal hypertension - where the blood pressure inside the liver is abnormally high, causing swollen veins (varices) to develop on the lining of the stomach and oesophagus.

Stomach cancer and oesophageal cancer -the endoscope can be used to remove samples of suspected cancerous tissue for testing. This is known as a biopsy.

Therapeutic gastroscopy

The two most common uses of a therapeutic gastroscopy are:

to stop bleeding inside the stomach or oesophagus - bleeding is commonly caused by a stomach ulcer, gastro-oesophageal reflux disease, or enlarged veins (varices) on the lining of the oesophagus or stomach.

to widen a narrowed oesophagus that's causing pain or swallowing difficulties (dysphagia).

The oesophagus can become narrowed or blocked for a number of reasons, including mouth cancer or lung cancer, radiotherapy, or an infection, such as tuberculosis or herpes simplex.

A gastroscopy that's used to widen the oesophagus is also known as a ‘gastroscopy with oesophageal dilatation’.

Other uses of therapeutic gastroscopy include:

treating cases of early-stage stomach cancer or throat cancer by removing any tumours (advanced cases will require more extensive surgery)

removing non-cancerous growths (polyps) that are causing an obstruction

removing objects that have become lodged in the oesophagus or stomach

providing nutrients by way of a feeding tube, when a person is unable to eat in the normal way

How a gastroscopy is performed  

Instructions about how to prepare for a gastroscopy should be included with your appointment letter.

Phone the hospital if there's anything you're unsure about.

Preparing for a gastroscopy

If you're referred for a gastroscopy, you'll need to stop taking any prescribed medicines for indigestion at least two weeks beforehand. This is because medication can mask some of the problems that a gastroscopy could find. You can continue to take antacids up until your endoscopy.

If you're taking any of the following medications, you should phone the endoscopy unit before your appointment because special arrangements may need to be made:

Don't wear nail polish on the day of your appointment because it can interfere with a device that's attached to your finger to monitor your oxygen levels.

It's important that your stomach is empty so that the whole area can be seen clearly. You'll be asked not to eat or drink anything for at least four hours before having a gastroscopy.

The procedure

A gastroscopy can take about 15 minutes, depending on why it's being carried out.

The procedure will usually be carried out by a nurse and an endoscopist (a healthcare professional who specialises in performing endoscopies). You'll meet the nurse before the procedure and they'll be able to answer any questions you have.

You should remove any glasses, contact lenses and false teeth. A nurse may then spray your throat with a local anaesthetic spray and insert a small plastic mouth guard to protect your teeth.

You'll be asked to lie down on your left-hand side and the nurse will attach a small probe to your finger. This measures your oxygen level and heart rate.

At this point, you'll usually be given an injection of sedatives into your arm. This will make you feel very drowsy so that you'll be mostly unaware of the procedure and will probably have no memory of it. However, you'll still be able to follow the instructions of the endoscopist or nurse.

The endoscopist will insert the endoscope into your throat and tell you to swallow it to help move it down into your oesophagus.

Diagnosing a condition

If the gastroscopy is being used to diagnose a certain condition, air will be blown into your stomach once the endoscope is inside. This allows the endoscopist to see any patches of redness, holes, lumps, blockages or other abnormalities.

If abnormalities are detected, a biopsy (tissue sample) can be taken and sent to a laboratory for closer examination under a microscope. You won't feel anything during a biopsy.

Treating bleeding varices

If you have bleeding varices (enlarged veins), the endoscopist will use the endoscope to locate the site of the bleeding.

If the bleeding varices are in your oesophagus, they can usually be treated using a technique called band ligation. This involves passing a small rubber band down the endoscope, which is used to seal the base of the varices and cut off the blood supply to prevent further bleeding.

If the bleeding varices are in your stomach, the site of the bleeding will be injected with a chemical called cyanoacrylate. Cyanoacrylate is the active ingredient used in superglue. It's also very useful in sealing holes or tears in body tissue.

Treating bleeding ulcers

If you have bleeding ulcers, a number of techniques may be used to treat them. For example:

During these procedures you may also receive an injection of a fast-acting acid-reducing medication, known as a proton-pump inhibitor, to prevent bleeding re-ocurring.

Narrowed oesophagus

If you have a narrowed oesophagus, the endoscopist can pass instruments down the endoscope to help stretch and widen it. The instruments can also be used to insert a rigid balloon or stent (a hollow plastic or metal tube) to hold the walls of your oesophagus open.


You'll usually be sedated during a gastroscopy, so you'll be very drowsy both during and after the procedure.

After the procedure, the endoscope will be removed and you'll be taken to a recovery room until the effects of the sedation have worn off.

If your gastroscopy was part of a treatment, you may be given a series of tests to assess how effective the treatment was and check for any complications. The tests may include a:

Depending on your individual circumstances, you'll then either be transferred to a hospital ward or discharged (sent home).

If you're discharged, you should arrange for someone to take you home and to stay with you for at least 12 hours after having the procedure.

Even if you feel very alert, the sedative can stay in your blood for 24 hours and you may experience further episodes of drowsiness. 

You therefore shouldn't drive, operate heavy machinery, or drink alcohol during this time.

Depending on the type of gastroscopy you have had, it may be several days before you can resume a normal diet.


If you've had a gastroscopy to diagnose a condition, a further appointment may be made so you can discuss the results with the doctor in charge of your care. Alternatively, the results may be sent to your GP.


1. The endoscope is placed into the mouth.

2. It is swallowed and moved down the oesophagus (gullet).

3. The endoscope is carefully fed into the stomach.

4. It's then moved into the first section of the small intestine (duodenum).

Risks of a gastroscopy 

A gastroscopy is a very safe procedure and the risks of serious complications are small.

A gastroscopy that's being used to diagnose a condition (diagnostic gastroscopy) has less than a 1 in 1,000 chance of causing a serious complication.

Due to being more invasive, a gastroscopy that's used to treat a condition (therapeutic gastroscopy) has a higher risk. However, the risk is still relatively small at around 1 in 100.

Possible complications of a gastroscopy include:

adverse effects from sedation


perforation (tearing)

These are discussed below.


Sedation is usually safe, but it can occasionally cause complications including:

feeling or being sick

a burning sensation at the site of the injection

small particles of food falling into the lungs and triggering an infection (aspiration pneumonia)

irregular heartbeat

breathing difficulties

Very rarely (about 1 in 25,000 cases), the complications from sedation can result in a stroke.


Sometimes, during a gastroscopy the endoscope can accidentally damage a blood vessel, causing it to bleed.

The site of the bleeding can usually be repaired using a further gastroscopy, in the same way that bleeding varices or an ulcer is repaired. A blood transfusion may also be required to replace lost blood.


During a gastroscopy, there's a small risk of the endoscope tearing the tissue inside your oesophagus, abdomen or chest.

The warning symptoms include:

neck pain

pain when swallowing

abdominal pain

high temperature

breathing difficulties

If the perforation isn't severe, it can usually be left to heal by itself. You may be given antibiotics to prevent an infection occurring at the site of the tear.

If the perforation is more serious (indicated by severe pain that doesn't respond to painkillers), surgery may be needed to repair it.

any medication that's used to treat diabetes, such as insulin or metformin

blood-thinning medication (used to prevent blood clots), such aslow-dose aspirin, warfarin or clopidogrel

a probe may be passed through the endoscope to apply heat or small clips to stop the bleeding

a weak solution of adrenaline may be injected around the ulcer to activate the clotting process, narrow the arteries and enhance blood clotting

chest X-ray

measure of your heart rate

blood pressure test