How do I diagnose and manage suspected pancreatitis and cholestasis?

Diagnosing Pancreatitis and Cholestasis

To rule out pancreatitis and cholestasis, specific laboratory tests and imaging studies are required, with the diagnostic approach determined by clinical presentation and initial test results.

Initial Laboratory Evaluation

• For suspected pancreatitis, obtain serum amylase or lipase levels, which are elevated in acute pancreatitis 1
• For cholestasis evaluation, measure alkaline phosphatase (AP) and gamma-glutamyl transferase (GGT), which are typically elevated in cholestatic conditions 1, 2
• Additional laboratory tests should include:
  • Liver function tests: bilirubin, AST, ALT 1
  • Triglyceride and calcium levels to evaluate potential causes of pancreatitis 1
  • Serum antimitochondrial antibodies (AMA) for suspected primary biliary cholangitis (PBC) 1

Imaging Studies

For Pancreatitis:

• Contrast-enhanced CT scan should be performed after 72 hours of illness onset in patients with predicted severe disease (APACHE II score >8) or evidence of organ failure 1
• CT should be used selectively based on clinical features in patients not meeting these criteria 1

For Cholestasis:

• Ultrasound is the first-line non-invasive imaging procedure to differentiate intrahepatic from extrahepatic cholestasis 1
• If ultrasound shows bile duct abnormalities or is inconclusive, proceed with magnetic resonance cholangiopancreatography (MRCP) 1, 3
• MRCP has 96-100% sensitivity for detecting bile duct stones and is preferred over diagnostic ERCP due to lower complication risk 3

Diagnostic Algorithm for Cholestasis

1. First step: Abdominal ultrasound to distinguish between intrahepatic and extrahepatic cholestasis 1
2. If extrahepatic obstruction is suspected:
   • Proceed with MRCP or endoscopic ultrasound (EUS) 1, 3
   • Reserve ERCP for therapeutic interventions rather than diagnosis due to its associated risks (pancreatitis 3-5%, bleeding 2%, cholangitis 1%, mortality 0.4%) 1, 3
3. If intrahepatic cholestasis is suspected:
   • Test for antimitochondrial antibodies (AMA) 1
   • If AMA is positive (≥1:40), diagnose primary biliary cholangitis 1
   • If AMA is negative, consider MRCP followed by liver biopsy if diagnosis remains unclear 1

Diagnostic Algorithm for Pancreatitis

1. First step: Measure serum amylase or lipase levels 1
2. If pancreatitis is confirmed:
   • Determine etiology through detailed history focusing on gallstones, alcohol use, hypertriglyceridemia, hypercalcemia, medications, trauma, and family history 1
   • Perform abdominal ultrasound to evaluate for gallstones or biliary obstruction 1
3. For severity assessment:
   • Calculate APACHE II score; scores >8 predict severe disease 1
   • Measure C-reactive protein (>150 mg/L at 48 hours suggests severe disease) 1
   • Monitor for organ failure 1

Special Considerations

• Consider cholestasis secondary to pancreatitis when both conditions are present, as pancreatic pseudocysts or inflammation can compress the common bile duct 4, 5
• In patients >40 years with unexplained pancreatitis, CT or EUS should be performed to rule out pancreatic malignancy 1
• In patients with recurrent unexplained pancreatitis, consider evaluation with EUS and/or ERCP 1
• If ERCP is performed, it should be done by an experienced endoscopist with capabilities for therapeutic intervention 1

Common Pitfalls to Avoid

• Do not rely solely on ultrasound to exclude common bile duct stones, as it may miss them despite elevated liver enzymes 3
• Do not perform diagnostic ERCP as first-line investigation due to its significant complication rate; use MRCP or EUS instead 1, 3
• Do not delay imaging in patients with predicted severe pancreatitis, as early detection of complications is crucial 1
• Do not overlook chronic pancreatitis as a cause of persistent cholestasis, especially in patients with alcohol-related disease 5, 6