A gastroscope is a specialised type of endoscope (literally 'a tool to look inside the body') that is used to examine sections of the digestive tract. A gastroscopy is described as a 'minimally invasive' procedure, that is, it does not require conventional open surgery or incisions as the gastroscope is a type of tube introduced via the mouth and throat.

The gastroscope is equipped with a small camera and light at the tip and also carries miniaturised surgical tools that allow some operations to be carried out during the procedure, such as taking tissue samples (biopsies) for analysis and stemming/stopping bleeding from an ulcer.

Endoscopic procedures such as gastroscopy (and colonoscopy) are much less stressful to the body than open surgery and as a result, not only are endoscopic procedures much quicker than their open procedure equivalents, recovery time is much quicker and there is no scarring from incisions, as is the case with open surgery.

Gastroscopy is often recommended to diagnose conditions relating to the oesophagus, the stomach or the duodenum (where symptoms might include abdominal pain, unexplained vomiting or bleeding in the digestive tract), as it allows a more accurate diagnosis than other techniques such as x-rays.

The only preparation required before a gastroscopy is to not eat or drink anything in the six hours immediately before the procedure.

Gastroscopies are performed under a mild sedative and in some cases a local anaesthetic is used on the back of the throat to stop the gag reflex as the gastroscope is introduced via the mouth. The whole procedure generally takes less than 30 minutes, after which patients are kept under observation for a further 2 hours before being permitted to go home.

As it takes a little longer for the effects of the anaesthetic to wear off, patients must not drive themselves home after the procedure and should not return to work on the same day.