Pancreatic pseudocysts are mostly a complication of acute and chronic pancreatitis, and can also be caused by pancreatic trauma, pancreatic tumors, and a few are idiopathic. Its incidence reaches 11-60%, and more than half of the patients with acute pancreatitis are complicated by pancreatic pseudocysts. The histological definition of pancreatic pseudocyst is a cyst containing pancreatic fluid or abundant pancreatic enzymes and the wall of the cyst lacks the epithelial layer of the pancreatic duct. The wall of the cyst is composed of granulation tissue, fibrous tissue or the posterior wall of the stomach, transverse colonic mesentery, and small omentum, etc. The anterior wall of the cyst, while its posterior wall is mostly composed of pancreatic tissue and retroperitoneal tissue. The regression of pancreatic pseudocysts: Studies have shown that about half of the pseudocysts can regress naturally, with a natural absorption rate of 20% to 68%. In particular, acute pancreatic pseudocysts with a history of less than 6 weeks and cysts less than 6 cm in diameter have a greater likelihood of regression, so the treatment of pancreatic pseudocysts complicated by acute pancreatitis requires more than half a year of follow-up, and those found to be greater than 6 cm in diameter require surgery or endoscopic treatment. For cysts smaller than 4 cm in diameter, the chance of dissipation or absorption is up to 90%, so surgery or endoscopic treatment is not required. Indications for treatment of pancreatic pseudocysts: Prompt treatment is required if the following conditions occur: gradual increase in cyst size with obvious clinical symptoms, such as cyst infection, intracystic hemorrhage, cyst rupture or cyst compression of the biliary or gastrointestinal tract causing obstructive jaundice or gastrointestinal obstruction, as well as pancreatic fistula, pseudoaneurysm of the splenic artery or hepatic artery, cyst compression of the splenic vein causing regional portal hypertension ( Left hemi-portal hypertension, manifesting splenomegaly, hypersplenism, bleeding by esophagogastric fundic varices or rupture) and other symptoms or complications, or pancreatic masses that do not exclude pancreatic cancer require surgical treatment, and for some appropriate cases endoscopic treatment may also be applied. Symptoms of pancreatic pseudocysts: The most common symptoms are abdominal pain, early satiety, nausea and vomiting, and weight loss. Physical examination may reveal epigastric pressure and palpable masses, and pancreatic amylase is persistently elevated in approximately 76% of patients with pancreatic pseudocysts. Departmental cases may present with symptoms of obstructive jaundice and duodenal obstruction mostly due to mass compression. If the cyst compression leads to regional portal hypertension may manifest as splenomegaly, leukocytopenia and thrombocytopenia, anemia and other hypersplenism, as well as upper gastrointestinal hemorrhage due to esophagogastric fundic varices or venous rupture. Individual patients with splenic artery or hepatic artery aneurysm may have sudden intra-abdominal hemorrhage. Common imaging tests and options: Color Doppler ultrasound is the most routine and convenient ancillary test, which is mostly used to monitor the changes of cysts and follow up. CT upper abdomen is the most accurate method to diagnose pancreatic pseudocysts, which can clarify whether they are pseudocysts or real cysts, and can accurately locate and understand the size of the cyst and its anatomical relationship with the surrounding area. MRI or MRCP of the upper abdomen is as good as CT examination and can understand the relationship between the cyst and pancreatic duct and bile duct, and whether the pancreatic duct is connected to the cyst. Endoscopic ultrasound can provide the most accurate evaluation of the intracapsular structure, enough to localize the pancreatic pseudocyst, understand its relationship with the location of the gastrointestinal wall and vascular distribution, and can also monitor the route of needle entry in real time to accurately puncture the cyst and place a drainage tube, and can also guide fine needle aspiration biopsy to clarify the nature of cystic fluid. Treatment 1. Conservative medical treatment: pancreatic pseudocysts meeting the following conditions can be treated conservatively first – after acute pancreatitis, pseudocyst <6 cm, cyst located in the head of the pancreas, persisting for <6 weeks, thin cyst wall, and pseudocyst located inside the pancreas. Growth inhibitors, pancreatic fluid preparations, etc. can be applied in the acute stage. 2.Endoscopic treatment: endoscopic treatment can be considered if the following conditions are met such as the distance between the stomach or duodenum and the cyst wall is less than 1cm, the cyst protrudes tightly against the stomach or duodenum, except for malignancy. Endoscopic treatment mainly includes the following ways: if the cyst is connected to the pancreatic duct, a catheter can be inserted into the cyst through the duodenal papilla to introduce the pancreatic fluid into the duodenum; endoscopically guided transgastric or transduodenal perforation and drainage; endoscopic cyst and gastrointestinal stoma, etc. The effect of endoscopic pancreatic pseudocyst drainage is inferior to surgical drainage, and the disappearance rate of pancreatic pseudocysts is low and the recurrence rate is high. 3, surgical treatment: traditional surgical treatment is mainly open cystic jejunostomy drainage or open transgastric cystic intragastric drainage, which is traumatic for patients and has a long postoperative recovery time. At present, minimally invasive surgery for pancreatic pseudocysts - laparoscopic internal drainage of cysts is developing faster and avoiding the drawbacks of open surgery, the surgical effect is comparable to open surgery and the long-term effect is significantly better than endoscopic internal drainage of cysts. Laparoscopic internal drainage of pancreatic pseudocysts is often used: 1. Laparoscopic intragastric drainage of pancreatic pseudocysts via the stomach: this procedure was first adopted by Indian doctors in 1994, and in recent years it was introduced to China by our hospital, which first used this procedure in China to treat pancreatic pseudocysts and achieved good results. This surgery is applicable to almost all cases of pancreatic pseudocysts. Because of the fast recovery and short hospitalization time after laparoscopic surgery, it avoids the common complications of traditional open surgery and has good long-term results after surgery. 2.Laparoscopic internal drainage of posterior gastric wall cyst: This procedure is also a minimally invasive surgery, in which the posterior gastric wall and the anterior wall of the cyst are revealed by opening the gastrocolic ligament under laparoscopy, and the posterior gastric wall and the anterior wall of the cyst are incised separately, and the incisions of both are sutured together so that pancreatic fluid from the pancreatic cyst can be introduced into the stomach. The posterior wall of the stomach is usually the wall of the pancreatic pseudocyst, and it is not possible to separate the two, so most patients are not suitable for this procedure. In addition, there are laparoscopic pancreatic pseudocyst jejunal drainage and other procedures, which are too complicated and more traumatic than the two above-mentioned procedures, and I recommend the first two procedures for pancreatic pseudocyst surgery.