With the progress of medicine, people are very familiar with gastroscopy and colonoscopy, but I believe that most people are still very unfamiliar with ultrasound endoscopy, so what is ultrasound endoscopy? Ultrasound endoscopy is a very small ultrasound probe placed in the front of the gastroscope, so that we can observe the abnormalities on the surface of the stomach through the gastroscope on the one hand, and the stomach wall or its surrounding conditions can be observed through ultrasound, just like a penetrating eye, penetrating the stomach wall to see the situation around the stomach. What can be seen by ultrasound gastroscopy? For example, if we do a gastroscopy and we find a polyp in the stomach, but we don’t know how deep it is and which layer it comes from, we can do it by ultrasound gastroscopy, if we find that it comes from the first layer of the stomach wall by ultrasound endoscopy, then we can be sure that it is a polyp, and also under the gastroscope we find something like a smooth muscle tumor or If we find that it originates from the second or fourth layer of the gastric wall through ultrasound endoscopy, then we can be sure that it is a polyp. With the popularization of gastroscopy, early cancer is found more and more often, and we want to know whether it can be removed through gastroscopy, then we can’t do it without ultrasound gastroscopy. The role of ultrasonic gastroscopy is not limited to this. Through the examination of GI cancer, it can accurately distinguish the depth of tumor invasion, the invasion of surrounding organs and lymph node metastasis, i.e. TNM stage, which is of great significance for the surgical resection of tumor. Ultrasound gastroscopy can even detect lesions of 2-3mm in size, which is difficult to do with CT, MRI and external ultrasound. The nature of the lesion can be clarified. The distal common bile duct and jugular abdomen have been nearly blind to extracorporeal ultrasound, but ultrasound endoscopy can easily complete the examination here through the duodenum, providing a clear direction for ERCP or surgical treatment. Patients with advanced tumors usually have poor quality of survival because of the pain of the tumor, etc., and we can improve the quality of survival by performing abdominal plexus treatment under ultrasound endoscopic guidance. While pancreatic pseudocysts are traditionally operated through surgery, which is highly traumatic and has a high chance of recurrence after surgery, ultrasound endoscopy is guided by an ultrasound probe to perform puncture and drainage, which is less traumatic and less expensive, with minimal postoperative complications and very few recurrences. The uses of ultrasound endoscopy are not limited to this, but there are more and more uses that have been developed and are being developed.