The Atlanta Classification and Definitions of Acute Pancreatitis Have Been Revised and Are Based on Worldwide Consensus

Background and Objective: In a complex disease such as acute pancreatitis, correct terminology and clear definitions are important. The clinically based Atlanta Classification was formulated in 1992, but in recent years it has been increasingly criticized. No formal evaluation of the use of the Atlanta definitions in the literature has ever been performed. Deficiencies identified and improved understanding of the disease make a revision necessary. Methods: A Medline literature search sought studies published after 1993. The guidelines, review articles, and their cross-references were reviewed to assess whether the Atlanta or alternative definitions were used. Revisions were made in response to comments. The consensus was reviewed, and only statements based on published evidence were retained. Results: The severity of the disease is classified as mild, moderate, or severe. Mild acute pancreatitis, the most common form, has no organ failure, local or systemic complications, and usually resolves in the first week. Moderately severe acute pancreatitis is defined by the presence of transient organ failure, local complications, or exacerbation of co-morbid disease. Severe acute pancreatitis is defined by persistent organ failure, that is, organ failure lasting more than 48 h. Local complications are peripancreatic fluid collections, pancreatic and peripancreatic necrosis (sterile or infected), pseudocysts, and walled-off necrosis (sterile or infected). We present a standardized template for reporting CT images. There was a large variation in the interpretation of the Atlanta definitions of local complications, especially relating to the content of peripancreatic collections. Conclusion: The Atlanta definitions for acute pancreatitis are often used inappropriately, and alternative definitions are frequently applied. Such a lack of consensus illustrates the need for a revision of the Atlanta Classification. So, the consensus provides clear definitions to classify acute pancreatitis using easily identified clinical and radiological criteria.