Current status of treatments of pancreatic and peripancreatic collections of acute pancreatitis.

Pancreatic and peripancreatic collections are the main local complications of acute pancreatitis with a high incidence. In the early phase, most acute pancreatic and peripancreatic collections can resolve spontaneously with supportive treatment. However, in some cases, they will develop into pancreatic pseudocyst (PPC) or walled-off necrosis (WON). When causing symptoms or coinfection, both PPC and WON may require invasive intervention. Compared to PPC, which can be effectively treated by endoscopic ultrasound-guided transmural drainage with plastic stents, the treatment of WON is more complicated and challenging, particularly in the presence of infected necrosis. In the past few decades, with the development of minimally invasive interventional technology especially the progression of endoscopic techniques, the standard treatments of those severe complications have undergone tremendous changes. Currently, based on the robust evidence from randomized controlled trials, the step-up minimally invasive approaches have become the standard treatments for WON. However, the pancreatic fistulae during the surgical step-up treatment and the stent-related complications during the endoscopic step-up treatment should not be neglected. In this review article, we will mainly discuss the indications of PPC and WON, the timing for intervention, and minimally invasive treatment, especially endoscopic treatment. We also introduced our preliminary experience in endoscopic gastric fenestration, which may be a promising innovative method for the treatment of WON.