Acute Pancreatitis Classification


Atlanta classification


Atlanta classification broadly classifies acute pancreatitis into two categories.


These are:


  • Interstitial edematous acute pancreatitis is characterized by the acute inflammation of the pancreatic parenchyma and surrounding peri-pancreatic tissue.
  • Necrotizing acute pancreatitis is characterized by necrosis of pancreatic parenchyma and peri-pancreatic tissue.

Necrotizing pancreatitis (NP) which is further subdivided into:


  1. parenchymal necrosis 
  2. peripancreatic necrosis
  3. combined type (peripancreatic and parenchymal necrosis): most common

Based on the severity of the disease, acute pancreatitis is divided into the following types;


  • In mild acute pancreatitis, there is the absence of local or systemic complications and organ failure.
  • In moderately severe acute pancreatitis are local complications with or without organic failure for less than 48 hours.
  • In severe acute pancreatitis, there is persistent organ failure for more than 48 hours with the involvement of one or more than one organ.

Two clinical phases of pancreatitis:


Early (1st week): in which severity is based on the presence or absence of systemic organ failure
Late (>1st week): in which severity is based on the presence of local complication or persistent systemic organ failure


New terminology for fluid collections associated with acute pancreatitis is introduced :


  • Fluid collections associated with interstitial edematous pancreatitis (i.e. minimal or no necrosis)
    • acute peripancreatic fluid collections (APFC): in the first 4 weeks: non-encapsulated peripancreatic fluid collections
    • pseudocysts: develop after 4 weeks; encapsulated peripancreatic or remote fluid collections
  • Fluid collections associated with necrotizing pancreatitis
    • acute necrotic collections (ANCs): in the first 4 weeks; non-encapsulated heterogeneous non-liquefied material
    • walled-off (pancreatic) necrosis (WON or WOPN): develop after 4 weeks; encapsulated heterogeneous non-liquefied material  

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