What is the workup for cholecystitis?

Workup for Cholecystitis

The diagnosis of acute cholecystitis requires a combination of detailed history, complete clinical examination, laboratory tests, and imaging investigations, with ultrasound being the first-line imaging modality. 1

Clinical Evaluation

History and Physical Examination

• Key symptoms to assess:
  • Right upper quadrant pain or tenderness
  • Fever
  • Nausea and vomiting
  • Food intolerance
• Key physical findings:
  • Murphy's sign (pain on inspiration when pressing on the right upper quadrant)
  • Right upper quadrant tenderness

Laboratory Tests

• Essential laboratory tests:
  • Complete blood count (CBC) - look for leukocytosis
  • C-reactive protein (CRP) - elevated in inflammation
  • Comprehensive metabolic panel (CMP) - assess liver function
  • Liver function tests (LFTs):
    • Bilirubin
    • Alkaline phosphatase (ALP)
    • Gamma-glutamyl transpeptidase (GGT)
    • Alanine aminotransferase (ALT)
    • Aspartate aminotransferase (AST)

Imaging Studies

First-Line Imaging

• Ultrasound of the right upper quadrant 1, 2
  • Sensitivity: 81%
  • Specificity: 83%
  • Findings suggestive of cholecystitis:
    • Gallstones
    • Gallbladder wall thickening (>3mm)
    • Pericholecystic fluid
    • Sonographic Murphy's sign

Second-Line Imaging (if ultrasound is inconclusive)

• Hepatobiliary Iminodiacetic Acid (HIDA) scan 1, 2
  • Most accurate test for diagnosing acute cholecystitis
  • Higher sensitivity (96%) and specificity (90%) than ultrasound
  • Non-visualization of the gallbladder indicates cystic duct obstruction

Additional Imaging (as needed)

• CT scan of abdomen with contrast 1, 2

  • Less sensitive than ultrasound for gallstones
  • Better for identifying complications:
    • Perforation
    • Emphysematous cholecystitis
    • Pancreatitis
    • Abscess formation

• MRI of abdomen 1

  • Similar sensitivity (85%) and specificity (81%) to ultrasound
  • Useful when ultrasound findings are equivocal
  • Can better visualize hepatic and biliary abnormalities

Evaluation for Common Bile Duct Stones (CBDS)

• Laboratory indicators:

  • Elevated liver enzymes (especially GGT with 80.6% sensitivity, 75.3% specificity) 1
  • Elevated bilirubin

• Imaging for suspected CBDS:

  • Magnetic resonance cholangiopancreatography (MRCP)
  • Endoscopic ultrasound (EUS)
  • Endoscopic retrograde cholangiopancreatography (ERCP) - diagnostic and therapeutic

Diagnostic Pitfalls to Avoid

1. Relying on a single clinical or laboratory finding - no single feature has sufficient diagnostic power to establish or exclude the diagnosis 1

2. Missing atypical presentations - acute cholecystitis may present without classic findings such as fever, leukocytosis, or positive Murphy's sign 3

3. Overlooking acalculous cholecystitis - accounts for 5-10% of cases, typically in critically ill patients 2, 4

4. Misinterpreting normal HIDA scans - a normal HIDA scan effectively excludes acute cholecystitis 2

5. Failing to evaluate for complications - such as gangrenous cholecystitis, emphysematous cholecystitis, or gallbladder perforation 5

Diagnostic Algorithm

1. Initial evaluation:

   • Clinical assessment (symptoms and physical examination)
   • Laboratory tests (CBC, CRP, LFTs)

2. First-line imaging:

   • Ultrasound of the right upper quadrant

3. If ultrasound is inconclusive:

   • HIDA scan

4. If complications are suspected:

   • CT scan with contrast

5. If common bile duct stones are suspected:

   • Additional imaging (MRCP, EUS)
   • Consider ERCP for diagnosis and treatment

Remember that early diagnosis and management of cholecystitis are crucial to prevent complications and improve outcomes. The gold standard treatment is laparoscopic cholecystectomy, ideally performed within 72 hours of diagnosis 1, 4.