Gastroscopy for stomach cancer

A gastroscopy is a test that looks at the inside of your food pipe (oesophagus), stomach and the first part of your small intestine (small bowel). Your doctor might arrange for you to have a gastroscopy to help diagnose stomach cancer. 

This is also called an endoscopy or oesophago gastric duodenoscopy (OGD).

Your doctor uses a long flexible tube (gastroscope) with a tiny camera and light on the end to look inside your stomach. They check the stomach for growths or abnormal looking areas.

They will take samples (biopsies) of any abnormal looking tissues and send them to the lab to be examined under a microscope. These biopsies show if the abnormal looking tissue is cancer. They can help your doctor to plan your treatment. Your doctor might need to repeat the biopsy if they need more information about your cancer.

Diagram of an endoscopy

Preparing for your test

You might have a blood test 2 days beforehand to check how well your blood clots.

Tell your doctor if you're having medicine that changes how your blood clots. This includes:
•    aspirin
•    clopidogrel
•    arthritis medicines
•    warfarin or heparin
•    apixaban or rivaroxaban
•    ticagrelor

Your doctor will tell you if you need to stop taking any other medicines.

You can't eat for 6 to 8 hours before the test but you might be able to drink sips of water up to 2 hours before your appointment. Your doctor or nurse gives you written instructions about this beforehand.

Talk to your doctor if not eating could be a problem for you. For example, if you have diabetes.

What happens?

Most people have a gastroscopy as an outpatient, which means you go home the same day. The test takes up to 15 minutes. But expect to be in the hospital for several hours.

First you meet your nurse who asks you about your medical history and any allergies you might have. They may check your blood pressure and heart rate.

Your nurse or endoscopist explains the procedure and asks you to sign a consent form. This is a good time to ask any questions you might have.

Some endoscopy units may ask you to change into a hospital gown, but you can usually have the test in your own clothes.

Usually you’re awake when you have the test, but you can choose to have a medicine (sedative) to help you relax. This makes you drowsy.

If you have any false teeth or wear glasses you need to remove them for the test. Your nurse puts a plastic guard in your mouth to protect your teeth from the gastroscope.

This animation shows how you have a gastroscopy (also called endoscopy), it lasts for 1 minute 19 seconds.

Having the test awake

Your endoscopist sprays the back of your throat with local anaesthetic to numb it and make it easier to swallow the tube. This may make you cough, your eyes may water and it may taste bitter.

You then lie on your left side.

It takes a few minutes for your throat to go numb. Your endoscopist passes the gastroscope into your mouth and down your throat to the oesophagus. The tube is slightly bigger than a pen and will be uncomfortable but shouldn’t be painful.

They ask you to swallow as the tube goes down. They can see the images from the gastroscope on a television screen. They may put a small amount of air into the tube to help them see your oesophagus, stomach and duodenum. This might make you feel like burping.

Your endoscopist takes samples (biopsies) through the gastroscope of any abnormal areas. This shouldn’t be painful.

At the end of the test, your endoscopist gently removes the gastroscope.

Having the test while drowsy

You lie down on the couch.

Your nurse puts a small plastic tube (a cannula) into a vein in your arm. They then inject the sedative into the cannula. It takes a few minutes for you to get more relaxed and drowsy. You are still able to follow instructions from your endoscopist and nurse.

They give you oxygen through a small plastic tube with prongs that sit just inside your nostrils. They also put a clip on your finger to check your oxygen levels and heart rate. 

Your endoscopist then passes the gastroscope down your throat. 

After your test

Your nurse or endoscopist will talk to you about how the test went, if they took any biopsies and when to expect the results.  They give you a written report of what happened. This is also sent to your GP.

You might have some bloating and discomfort lasting a few hours after the gastroscopy. 

If you haven’t had sedation, you can usually go home shortly after having the test. You won't be able to eat or drink until the local anaesthetic spray has worn off. This takes about an hour.

If you had sedation, you stay in the endoscopy unit for an hour or two to recover. You may not remember much (if anything) about the test. You need a friend or relative to take you home and stay overnight.

For 24 hours after having sedation, you shouldn't:
•    drive
•    drink alcohol
•    operate heavy machinery
•    sign any important documents

Possible risks

A gastroscopy is a very safe procedure. Your nurse will tell you who to contact if you have any problems after the test. Your doctor will make sure the benefits of having a gastroscopy outweigh the possible risks.

Some of the risks include:


If you have a biopsy you may have a small amount of bleeding. This usually stops on its own. If it doesn’t you might need to go into hospital to stop the bleeding.

Sore throat

This is common after having an endoscopy and lasts a few days. Contact the hospital if you have severe pain in your throat, chest or tummy (abdomen).


There is a very small risk that after a biopsy the wound can become infected. If you have a temperature, feel hot and cold or shivery, or feel generally unwell, you should contact your GP.

Damage to teeth

There’s a small chance the gastroscope can damage your teeth during the test. The mouth guard helps prevent this from happening.

Chest infection

There’s a small risk of breathing in spit (secretions) that you would normally swallow. This is because your throat is numb or from the sedation making you sleepy. Your nurse protects your airway by suctioning away any secretions during the procedure. 

Reaction to the sedation

Occasionally sedation can cause problems with your breathing, heart rate and blood pressure. The risks are higher in older people and those with lung or heart problems. Your nurse closely watches you for any problems during the test, so they can treat it quickly.

Tear or hole (perforation)

There’s a very small risk of the gastroscope causing a tear in the lining of your oesophagus, stomach or duodenum. You might need an operation to repair this.

Getting your results

You will get some results before you go home.  It takes a little longer for your biopsy results.  You should get your biopsy results within 1 to 2 weeks, but it may take longer. The specialist doctor at the hospital might give you your results. Or you might see your GP.

Waiting for results can make you anxious. You can ask your doctor or nurse how long it takes to get them. Contact the doctor who arranged the test if you haven't heard anything after a couple of weeks.