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Revised Atlanta classification of acute pancreatitis

Last revised by Mohammad Taghi Niknejad on 22 Jun 2023

The Revised Atlanta classification of acute pancreatitis from 2012 is an international multidisciplinary classification of the severity of acute pancreatitis, updating the 1992 Atlanta classification.

The worldwide consensus aims for an internationally agreed-upon classification of acute pancreatitis severity, with standardized terminology for pancreatitis and its complications.


The classification system is based on both local and systemic determinants of severity, with:

  • local determinants related to the presence or absence of
    • (peri)pancreatic necrosis
      • sterile or infected
  • systemic determinants related to the presence or absence of
    • organ failure
      • transient or persistent

The grade of severity (mild, moderate, severe, and critical) is based on combinations of these determinants.

Furthermore, discrimination was made between 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

The Atlanta classification divides acute pancreatitis into two basic types:

All types of necrotizing pancreatitis may be sterile or infected; gas formation is the best imaging feature to suggest infection.

Treatment decisions in the late phase rely heavily on morphologic criteria. The role of the radiologist is to aid in treatment planning by correctly addressing the morphologic changes.

New terminology for fluid collections associated with acute pancreatitis is introduced 4,5:

ANCs and WONs are collections that contain both fluid and necrotic material of various amounts (an important point to differentiate them from APFCs and pseudocysts, however, in indeterminate cases follow-up is recommended).

The terms pancreatic abscess and intrapancreatic pseudocyst are totally abandoned in this new classification.

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