What is the recommended approach for investigating and managing a patient with suspected acute pancreatitis, considering their medical history, demographics, and potential underlying causes such as gallstones, hypertriglyceridemia, or alcohol abuse?

Investigation of Acute Pancreatitis

Diagnostic Confirmation

The diagnosis of acute pancreatitis requires meeting 2 of 3 criteria: characteristic epigastric abdominal pain radiating to the back, serum lipase or amylase levels ≥3 times the upper limit of normal, and imaging findings consistent with pancreatitis. 1

• Obtain serum lipase or amylase at admission, though be aware that levels may be normal or only minimally elevated in hypertriglyceridemia-induced pancreatitis 2, 3
• CT scanning with intravenous contrast is the preferred confirmatory imaging test when diagnosis is uncertain, but should be delayed until 72 hours after symptom onset to avoid underestimating the extent of pancreatic necrosis 2
• Early CT (within 72 hours) is unreliable for assessing necrosis and should be avoided unless there is diagnostic uncertainty 2

Initial Laboratory Workup

At admission, obtain the following tests to establish etiology 2:

• Serum amylase or lipase level
• Liver chemistries (bilirubin, AST, ALT, alkaline phosphatase) - elevated aminotransferases or bilirubin suggest gallstone etiology 2
• Triglyceride level - levels >11.3 mmol/L (≈1000 mg/dL) indicate hypertriglyceridemia as the cause 3
• Serum calcium level - to identify hypercalcemia as a potential cause 2
• If triglycerides cannot be measured acutely, obtain fasting levels after recovery 2

Severity Assessment

All patients should be risk-stratified using the APACHE II scoring system with a cutoff of 8 to predict severe disease. 2

• Patients with APACHE II score >8 or evidence of organ failure during the initial 72 hours require contrast-enhanced CT after 72 hours to assess for pancreatic necrosis 2
• C-reactive protein >150 mg/L at 48 hours after disease onset is an adjunctive marker for severe disease 2
• Patients with predicted severe disease, actual severe disease, or persistent organ failure should be triaged to an intensive care unit or intermediate care unit 2

Etiological Investigation

Immediate Imaging

Perform abdominal ultrasonography at admission to screen for cholelithiasis or choledocholithiasis. 2

• If the initial ultrasound is inadequate or negative but gallstone pancreatitis is still suspected, repeat ultrasonography after recovery 2
• Endoscopic ultrasonography (EUS) can serve as an accurate alternative to screen for gallstones and bile duct stones 2

History Focus

Document the following specific risk factors 2:

• Previous gallstone symptoms or documentation
• Alcohol use quantified in units per week
• History of hypertriglyceridemia or hypercalcemia
• Family history of pancreatic disease
• Complete prescription and nonprescription drug history
• History of trauma
• Presence of autoimmune diseases

Advanced Evaluation for Unexplained Cases

For patients over age 40 with unexplained pancreatitis, perform CT or EUS to exclude underlying pancreatic malignancy. 2

• In patients under 40 with a single episode of unexplained pancreatitis, extensive evaluation is not recommended 2
• For recurrent unexplained pancreatitis, EUS is preferred as the initial advanced test over ERCP 2, 4
• If ERCP is performed for recurrent disease, it must be done by an endoscopist with training and facilities for therapeutic intervention including minor papilla sphincterotomy, pancreatic duct stent placement, and sphincter of Oddi manometry 2

Common Pitfalls

• Do not accept "idiopathic" pancreatitis without thorough investigation - etiology should be established in at least 75-80% of cases 2
• Avoid early CT (before 72 hours) for severity assessment as it underestimates necrosis 2
• Be aware that lactescent (milky) serum suggests severe hypertriglyceridemia, which may present with normal or minimally elevated pancreatic enzymes 3
• Do not perform extensive invasive evaluation in young patients (<40 years) with a single episode of unexplained pancreatitis 2