What is a gastroscopy?

A gastroscopy is a procedure that enables the doctor to see inside your stomach. A fibreoptic tube (gastroscope) is used to visualize the surface of the stomach. The scope is 120-140cm long and just under 1cm wide. It has a camera and a light at the end as well as a channel where fine flexible instruments can be passed through to obtain a sample or perform a small procedure such as a polypectomy.

The stomach is opened up (insufflated) ahead of the scope using gas insufflations. The gastroscope is also equipped with suction to help clear the stomach contents allowing visualization of the surface.

The procedure is also called an upper gastrointestinal (GI) endoscopy because is inserted through the mouth into the oesophagus, stomach and the first part of the intestine called the duodenum.

The scope is inserted under vision and a systematic assessment is made of the oesophagus, stomach and duodenum. Photos are taken and routine biopsies (samples) may be obtained from the stomach and duodenum. Any abnormality seen is usually biopsied.

Polyps (growths from the wall of the gastrointestinal tract – GIT) may be seen in the stomach. Depending on their appearance and number, they may be sampled or removed – called a polypectomy.

What does a gastroscopy involve?

The procedure is done under an anaesthetic called sedation. The anaesthetist will discuss this further with you after taking a brief anaesthetic history. A cannula will be inserted into one of the veins in your hand or arm.

The anaesthetist may then ask you to open your mouth to spray a numbing substance into the back of your throat to make insertion of the gastroscope more comfortable.

You will then be asked to lie on your left-hand side and open your mouth for a mouth guard to be put in. The mouth guard protects your teeth and also protects the scope from your teeth. This is the last step you are likely to remember when you wake up.

An anaesthetic agent then is injected into your vein via this cannula. The aim is to make you sleepy enough but not to give you a full anaesthetic. The difference between sedation and full anaesthetic is that during sedation, you are still able to protect your own airway which means you do not have to have a breathing tube put in.

The average duration of a routine gastroscopy with routine biopsies is around 10 minutes. You will, however, be in the endoscopy room and recovery room for a longer time to allow for administration of your anaesthetic and recovery from it.

What are the risks of the procedure?

Aspiration is when something other than air enters your trachea into the lungs. This can happen during a gastroscopy if you have fluid in the stomach which refluxes back up the oesophagus during your procedure.

Aspiration can result in breathing problems.

The risk of aspiration is minimized by having an empty stomach which is why you should adhere to the fasting instructions.

Perforation refers to a hole or a tear of the wall of the gastrointestinal tract during upper GI endoscopy. It can happen to the oesophagus, stomach or duodenum.

The risk is highest in the oesophagus and is around 3 in 1000.

The risk increases when procedures are performed such as biopsies (taking samples), polypectomies or dilatation of strictures (opening up a narrowing).

A perforation is a serious complication that usually requires an endoscopic or surgical intervention to fix.

Minor bleeding associated with biopsies is usually not significant enough to be noticed.

The risk of significant bleeding increases with removing larger growths / polyps.

This may show as passing dark black stools (melaena).

Before the procedure

Fast from midnight for a morning procedure


From 7am for an afternoon procedure.

You can have clear fluids until 4 hours before the procedure

You will be contacted by the hospital the day before your procedure to let you know what time to come in. This is usually 1-2 hours before your procedure to allow for the hospital check-in procedures.

After your procedure

You may feel some minor bloating because of the gas used to insufflate the stomach but you should have no pain.

You may also experience a mild sore throat from the gastroscope having passed through the throat.

You can go home once you have recovered from the anaesthetic and had a light meal. This is usually within 1-2 hours of your procedure.