In fact, gastric examination generally is divided into two types, namely gastroscopy and gastric ultrasonography. To put it simply, "gastric ultrasonography" is to let the patient drink a bowl of special contrast agent and then do an ultrasound on the stomach. It is painless, non-invasive, without cross infection, especially suitable for the elderly and children. It makes up for the lesions in the gastric wall that cannot be displayed by X-ray and gastroscope.