Classification of acute pancreatitis.

Increased knowledge of the natural history, etiology, morphology, complications and systemic response of the patient to acute pancreatitis has led to a rapid evolution in the classification of acute pancreatitis. It is recommended that the following elements be included in a classification system of acute pancreatitis: 1. A definition of acute pancreatitis and its complications based on CT scan, ultrasound, ERCP, and angiographic and histologic findings. 2. A statement regarding the etiology of the patient's pancreatitis. 3. An assessment of the patient's systemic response to his or her pancreatitis by means of APACHE II and/or Ranson's signs of severity. This system, through the use of ultrasound, CT scan with vascular enhancement, and clinical and laboratory tests, can be utilized to classify patients initially, on the day of hospital admission, with regard to etiology, morphology, and physiologic severity. Later in their hospital course, the complications of pancreatitis, e.g., fluid collections, necrosis, pseudocysts, infected necrosis, abscesses, fistulas, pancreatic, enteric, and cutaneous, pseudoaneurysm, and splenic vein thrombosis, can be added to the classification as modifiers when and if they occur. The process of the development and confirmation of theories of the origin and nature of the cosmos and evolution of concepts regarding the classification of pancreatitis have something in common. Theory generally stimulates experimental observation whose purpose is to test the theory's validity. New theories are generated when experimental observations demonstrate inconsistencies in previously held beliefs. Just as our understanding of the cosmos is undergoing constant change based on new data and new theories, so are our concepts regarding the classification of pancreatitis.