Gastroesophageal reflux disease (GERD) is a condi-tion of reflux of gastric content into the esophagus, whichcould create clinical symptoms. Reflux can occur under normal conditions, usually related to certain conditions, such as lying down after meals and during vomitting. If reflux occurs, the esophagus would immediately contract to cleanse the lumen from refluxate, preventing prolonged contact between the refluxate and the esophageal mucosa.