Gastroscopy or upper gastrointestinal endoscopy is a procedure to visualise the inside of the oesophagus, stomach and duodenum (first part of the small intestine). It involves the use of a thin flexible tube called an endoscope that is inserted through the mouth to reach the intestines. The endoscope contains a camera and light source to provide a clear magnified view of these structures. Instruments may be inserted through the endoscope to carry out certain procedures.

A gastroscopy may be performed for diagnostic or therapeutic reasons. It can be used to determine the cause for abdominal pain or swallowing abnormalities. It can identify stomach ulcers, polyps, tumours and conditions such as gastroesophageal reflux disease. Instruments may be used to clear an oesophageal blockage, treat a bleeding ulcer or remove a tumour.

Gastroscopy is performed as an outpatient procedure. A sedative may be administered to keep you comfortable. Your throat is first numbed with an anaesthetic spray. The endoscope is then introduced through your mouth and you are asked to swallow the tip of the tube. The tube is then slowly guided down your oesophagus, through your stomach into the duodenum (first part of your intestine). Your doctor carefully evaluates these structures as the scope passes through and if possible treatment is performed through the scope. The entire procedure takes about 15 minutes or longer if a corrective procedure is being performed.

The procedure is usually quite safe but may rarely be associated with certain complications such as damage to the inner lining of the tract which can lead to perforation or bleeding.