What lab work is used to diagnose cholecystitis?

Laboratory Tests for Diagnosing Cholecystitis

Laboratory tests for diagnosing cholecystitis should include liver function tests, inflammatory markers, and complete blood count, with elevated alkaline phosphatase, glutamyl transferase, white blood cell count, and C-reactive protein being particularly indicative of the condition. 1

Key Laboratory Tests

Essential Laboratory Tests

• Complete Blood Count (CBC)

  • Leukocytosis (elevated white blood cell count) is a systemic sign of inflammation 1, 2
  • Typically shows neutrophilia in acute cholecystitis

• Liver Function Tests (LFTs)

  • Elevated alkaline phosphatase (ALP) 1
  • Elevated gamma-glutamyl transferase (GGT) 1
  • Bilirubin levels (may be elevated, especially if there is common bile duct obstruction) 1
  • Transaminases (AST/ALT) may be mildly elevated

• Inflammatory Markers

  • C-reactive protein (CRP) - elevation is a systemic sign of inflammation 2
  • Erythrocyte sedimentation rate (ESR) may be elevated

Additional Laboratory Tests

• Pancreatic Enzymes

  • Amylase and lipase to rule out concurrent pancreatitis
  • May be elevated if gallstone pancreatitis is present

• Blood Cultures

  • Indicated in patients with suspected sepsis or cholangitis
  • Should be obtained before starting antibiotics

Laboratory Findings in Risk Stratification

Laboratory results help stratify patients into risk categories for common bile duct stones 1:

Risk Category	Probability of CBD Stones	Laboratory Characteristics
Low	<10%	Normal liver enzymes
Intermediate	10-50%	Abnormal liver enzymes
High	>50%	Bilirubin >4 mg/dL, signs of cholangitis

Limitations of Laboratory Testing

• Laboratory tests alone are insufficient for diagnosis
• Must be combined with clinical presentation and imaging studies
• Normal laboratory values do not exclude cholecystitis 3
• Critically ill or sedated patients may not exhibit typical laboratory findings 1

Diagnostic Algorithm

1. Obtain CBC, LFTs, and inflammatory markers in patients with suspected cholecystitis
2. If laboratory tests show elevated inflammatory markers (WBC, CRP) and/or abnormal LFTs, proceed to imaging
3. Ultrasonography is the first-line imaging modality (sensitivity 81-88%, specificity 80-83%) 1, 3
4. If ultrasound is equivocal but clinical suspicion remains high, consider HIDA scan (gold standard for diagnosis with sensitivity 86.7-89.3% and specificity 66.8-79%) 1, 3

Common Pitfalls and Caveats

• Relying solely on laboratory tests for diagnosis can lead to missed cases, as some patients may have normal laboratory values despite having cholecystitis
• Laboratory abnormalities may be subtle in elderly patients or those with immunosuppression
• Elevated liver enzymes may indicate common bile duct involvement rather than just cholecystitis
• In acalculous cholecystitis (5-10% of cases), laboratory findings may be less specific due to underlying critical illness 3
• Laboratory tests should be interpreted in the context of clinical presentation and imaging findings for accurate diagnosis 1, 2