Overview】Pancreatic pseudocysts are pancreatic fluid containing a variety of digestive enzymes leaking from necrotic pancreatic tissue into the peri-pancreatic area, causing an inflammatory reaction and fibrin deposition, which forms a fibrous envelope after a week to several weeks. Pseudocysts are different from true cysts of the pancreas. A true cyst means that the cyst is within the pancreas and the inner layer of the cyst is composed of glandular ducts or alveolar epithelial cells, mostly congenital cysts. Pseudocysts, however, are cysts formed by the fibrous cyst wall formed by the tissue around the pancreas, and there are no epithelial cells inside the cyst wall, so they are called pseudocysts. Most pseudocysts are caused by acute pancreatitis, and a few are caused by pancreatic trauma or pancreatic cancer. A small number of pseudocysts are asymptomatic and are only detected during ultrasound examination. Most of the cases have clinical symptoms caused by the cyst pressing on adjacent organs and tissues. Abdominal pain occurs in about 80% to 90% of cases, and the pain is mostly in the upper abdomen, often radiating to the back. In addition to nausea, vomiting, decreased appetite, low-grade fever, diarrhea, jaundice and other symptoms caused by compression symptoms, pancreatic pseudocysts can also be complicated by serious and fatal cyst infection, cyst rupture, bleeding and perforation. Treatment】 Endoscopic ultrasound-guided pancreatic pseudocyst puncture and drainage is the preferred minimally invasive treatment option for pancreatic pseudocysts behind the gastric wall, and other treatment methods include percutaneous drainage and surgical cyst drainage. [Preoperative preparation] Complete relevant examinations, sign the informed consent for treatment before surgery, and understand the purpose and complications of endoscopic ultrasound-guided pancreatic pseudocyst puncture and drainage. Patients should fast for 12 hours and abstain from water for 6 hours before surgery, and lidocaine syrup should be included 5 minutes before surgery. Postoperative treatment】 Postoperative fasting should be followed by water fasting, and the transition should be made gradually from fluid to semi-liquid after food can be eaten, and attention should be paid to rest and avoid strenuous exercise after surgery. Give rehydration, application of enzyme suppression, acid suppression, mucosal protective agent and other drugs, and closely observe whether there is bleeding, perforation, infection, such as: fever, abdominal pain, blood in the stool, etc. If the cyst shrinks, the drainage tube will be removed endoscopically; otherwise, further treatment is needed.