Gastroscopy is an examination used to directly view the lining of the stomach, the pylorus and the duodenum. The examination is performed by means of an endoscope, or an elastic tube with visual tracks, making it possible to present images from inside the gastrointestinal tract on a colour monitor. An important advantage of an endoscope is the fact that, during a single procedure, it allows for the assessment of the mucous membrane and the collection of a small specimen of suspected tissues for further examination.