A gastroscopy is a procedure where a thin, flexible tube called an endoscope is used to look inside the oesophagus (gullet), stomach and first part of the small intestine (duodenum). It’s also sometimes referred to as an upper gastrointestinal endoscopy. The endoscope has a light and a camera at one end. The camera sends images of the inside of your oesophagus, stomach and duodenum to a monitor.

A gastroscopy can be used to:

  • Investigate problems such as difficulty swallowing (dysphagia) or persistent abdominal (tummy) pain
  • Diagnose conditions such as stomach ulcers or gastro-oesophageal reflux disease (GORD)
  • Treat conditions such as bleeding ulcers, a blockage in the oesophagus, non-cancerous growths (polyps) or small cancerous tumours
  • A gastroscopy used to check symptoms or confirm a diagnosis is known as a diagnostic gastroscopy
  • A gastroscopy used to treat a condition is known as a therapeutic gastroscopy


  • A gastroscopy often takes less than 15 minutes, although it may take longer if it’s being used to treat a condition
  • It’s usually carried out as an outpatient procedure, which means you won’t have to spend the night in hospital
  • Before the procedure, your throat will be numbed with a local anaesthetic spray. You can also choose to have a sedative, if you prefer. This means you will still be awake, but will be drowsy and have reduced awareness about what’s happening
  • 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
  • The procedure shouldn’t be painful, but it may be unpleasant or uncomfortable at times

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 unusual redness, holes, lumps, blockages or other abnormalities
  • It may feel a bit uncomfortable when the air is blown into your stomach, and you may burp or feel bloated. This should start to improve once the procedure is finished
  • If abnormalities are detected, a tissue sample (biopsy) can be removed and sent to a laboratory for closer examination under a microscope. You won’t feel anything while the sample is removed

Treating bleeding varices

  • If you have bleeding varices (enlarged veins), the endoscopist will use the endoscope to locate the site of the bleeding
  • They can then stop the bleeding by either tying the base of the varices with a small rubber band (band ligation), or injecting them with a chemical that seals the hole or tear in the blood vessel (sclerotherapy)

Treating bleeding stomach ulcers

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

  • A probe may be passed through the endoscope to seal the ulcer with heat, or small clips may be used to stop the bleeding
  • Medication may be injected around the ulcer to activate the clotting process