What is the initial workup and management for a patient with suspected pancreatitis?

Pancreatitis Workup

Diagnostic Confirmation

The diagnosis of acute pancreatitis requires two of three criteria: characteristic upper abdominal pain, serum lipase or amylase ≥3 times the upper limit of normal, and/or imaging findings consistent with pancreatitis. 1

Biochemical Testing

• Serum lipase is the preferred diagnostic test over amylase due to superior sensitivity and specificity, particularly in alcoholic pancreatitis and delayed presentations, as lipase remains elevated longer in serum 2, 3
• Serum amylase ≥4 times normal (or lipase ≥2 times normal) confirms the diagnosis in the appropriate clinical setting 4
• A normal amylase does not exclude pancreatitis in hyperlipidemic pancreatitis, acute-on-chronic pancreatitis, or delayed presentations 3
• Do not measure both amylase and lipase simultaneously—this does not improve diagnostic accuracy 3
• Daily enzyme measurements after diagnosis have no value in assessing clinical progress and should be avoided 3

Initial Laboratory Panel

Obtain the following tests at admission to establish etiology and assess severity:

• Liver function tests (bilirubin, AST, ALT, alkaline phosphatase) to evaluate for gallstone pancreatitis—the most common etiology 2
• Serum triglycerides to identify hypertriglyceridemia (levels >1000 mg/dL indicate this as the cause) 2
• Serum calcium to assess for hypercalcemia 2
• Complete blood count, renal function, glucose for severity assessment 1
• Hematocrit >44% is an independent risk factor for pancreatic necrosis 2
• Blood urea nitrogen >20 mg/dL independently predicts mortality 2

Imaging Studies

Initial Imaging

• Obtain abdominal ultrasound at admission to evaluate for gallstones or bile duct dilation, though pancreatic visualization is limited in 25-50% of cases 4, 2
• Chest and abdominal plain radiographs should be performed to provide baseline and exclude other pathology such as perforated viscus 4

Advanced Imaging

• Contrast-enhanced CT should be performed after 72 hours (not earlier) in patients with predicted severe disease or organ failure, as early CT underestimates pancreatic necrosis 2, 5
• CT is indicated for diagnostic purposes only if clinical and biochemical findings are inconclusive 4
• Do not perform routine CT in mild pancreatitis unless clinical deterioration occurs 5, 6

Severity Stratification

Severity assessment must be performed immediately using objective criteria, as failure to stratify early may result in potentially avoidable deaths. 4, 5

Clinical Assessment

• Clinical assessment alone is unreliable and misclassifies approximately 50% of patients 4
• Presence of organ failure (pulmonary, circulatory, or renal insufficiency) indicates severe disease 4

Laboratory Markers for Severity

• C-reactive protein (CRP) at 48 hours is the preferred laboratory marker, with values >150 mg/L (or >210 mg/L in first 4 days) indicating severe disease 4, 2, 1
• APACHE II score >8 indicates severe disease 2, 5
• Glasgow criteria ≥3 (assessed over 48 hours) constitutes severe disease 4
• Procalcitonin is the most sensitive test for detecting pancreatic infection, with low values strongly predicting absence of infected necrosis 2

Etiologic Workup Requirements

A comprehensive etiologic evaluation must be performed at admission, with the underlying cause established in at least 75% of cases. 2

Gallstone Pancreatitis Indicators

• Elevated bilirubin, ALT, or alkaline phosphatase suggest biliary etiology 2
• Urgent ERCP (within 24 hours) is indicated for concomitant cholangitis 2, 5
• Early ERCP (within 72 hours) is indicated when there is high suspicion of persistent common bile duct stone (visible stone on imaging, persistently dilated CBD, or jaundice) 2, 5

Additional Etiologic Testing

• Endoscopic ultrasound (EUS) can be used as an accurate alternative to screen for gallstones and bile duct stones if initial ultrasound is inadequate 2
• Do not perform extensive evaluation in patients <40 years with a single episode of unexplained pancreatitis—reserve invasive testing for recurrent episodes 2

Diagnostic Timeline

The correct diagnosis of acute pancreatitis should be made within 48 hours of admission to avoid missing alternative life-threatening intra-abdominal catastrophes. 4

Common Pitfalls to Avoid

• Do not routinely monitor amylase or lipase in asymptomatic patients 4
• Do not rely on peritoneal fluid aspiration as a routine procedure, though it may be considered when peritoneal fluid is detected without other signs of pancreatitis 4
• Do not delay CT beyond 72 hours in severe disease, but also do not perform it too early as it underestimates necrosis 2, 5
• Laparotomy is rarely warranted and should only be considered when clinical suspicion of peritonitis is high and all other tests including CT are inconclusive 4