Definition of Acute Pancreatitis
Acute pancreatitis is defined as acute inflammation of the pancreas, diagnosed when at least 2 of the following 3 criteria are present: (1) abdominal pain consistent with pancreatitis (typically epigastric pain radiating to the back), (2) serum lipase and/or amylase greater than 3 times the upper limit of normal, and (3) characteristic findings of pancreatic inflammation on cross-sectional abdominal imaging. 1, 2, 3
Core Diagnostic Criteria
The diagnosis requires at least 2 of 3 criteria to be met 2, 4:
Clinical presentation: Upper abdominal pain (typically epigastric, often radiating to the back) with associated nausea/vomiting and epigastric or diffuse abdominal tenderness on examination 1, 2
Biochemical evidence: Serum lipase and/or amylase >3 times the upper limit of normal 1, 2, 5
Imaging findings: Characteristic findings of pancreatic inflammation on contrast-enhanced CT or other cross-sectional imaging 2, 4
Pathophysiology
Acute pancreatitis represents an inflammatory process within the pancreas that occurs when intracellular protective mechanisms to prevent trypsinogen activation or reduce trypsin activity are overwhelmed 3, 6:
The earliest events occur within acinar cells, where premature activation of digestive enzymes leads to autodigestion of pancreatic tissue 6, 7
Pancreatic intracellular calcium overload, mitochondrial impairment, and inflammatory responses are critical pathogenic mechanisms 8
Acinar cell injury triggers a local inflammatory reaction that can progress to systemic inflammatory response syndrome (SIRS) in severe cases 7
Disease Spectrum and Clinical Significance
Acute pancreatitis is heterogeneous and often unpredictable in its progression 3:
Most patients (approximately 80%) experience mild, self-limited disease lasting a few days 3
Nearly one-fifth of patients develop complications, including pancreatic necrosis and/or organ failure, requiring prolonged hospitalization and intensive care 3
Severe disease with persistent organ failure (>48 hours) carries significant mortality risk, with rates up to 20-30% in ICU-admitted patients 4, 9
Common Etiologies
The most frequent causes include 1, 8:
Gallstone disease (most common cause, due to impaction at the distal common bile-pancreatic duct) 6
Hypertriglyceridemia (levels >1000 mg/dL or 11.3 mmol/L) 1, 2
Medications 8
Hypercalcemia 1
Approximately 18% of cases are idiopathic despite thorough workup 10
Clinical Presentation Features
Beyond the core diagnostic criteria, patients may exhibit 2:
Body wall ecchymoses (rare but indicative of severe disease): Cullen's sign (periumbilical discoloration) or Grey-Turner's sign (flank discoloration) 2
Occasionally, patients present with unexplained multiorgan failure or SIRS even without classic abdominal pain, particularly in postoperative settings 1