Fluid collections associated with acute pancreatitis: a pictorial essay

The terminology and classification scheme of acute pancreatitis proposed at the initial Atlanta Symposium was reviewed, and a new consensus statement was recently proposed. Major changes include subdividing acute fluid collections in the first 4 weeks into "acute peripancreatic fluid collection" and "acute necrotic collection" based on the presence of necrotic debris. Delayed fluid collections have been similarly subdivided into "pseudocyst" and "walled-off necrosis." Correct use of the new terms that describe these collections is important because they lead to different treatment decisions. The purpose of this article is to present an overview of fluid collections associated with acute pancreatitis, with an emphasis on their prognostic significance and impact on clinical management, and to illustrate the new terminology.