Gastroscopy is possible to examine the esophagus (esophagus). During a gastroscopy, the gastroscope passes through the esophagus, allowing a clear view of the structure and mucosa of the esophagus, or if there is an obstruction or stricture, the gastroscope cannot pass through the esophagus into the stomach. In order to see the mucosa of the digestive tract clearly, it is necessary to make the examined area free of mucus and food residue, neither food nor blood clots remain, the esophagus examination is to see if there is anything growing in the esophagus, if there is ulceration in the esophagus, if the gastroscopy is done in the morning, after 8 pm the night before the examination, do not eat any more food, also please do not smoke, and the dinner the day before should be light, easy to digest and less residue Gastroscopy is the most reliable method to diagnose esophageal, gastric and duodenal diseases, and can clearly see the pathological changes of esophagus, stomach and duodenum. Most of the lesions in the esophagus can be detected by gastroscopy. During gastroscopy, you can also distinguish between normal and abnormal mucosa by spraying special care cream stain. Depending on the characteristics of the lesion, it is sometimes necessary to do CT or barium meal imaging to further clarify the diagnosis.