What is the workup for cholecystitis?

Diagnostic Workup for Cholecystitis

The diagnostic workup for cholecystitis should include a combination of detailed history, physical examination, laboratory tests, and imaging studies, with abdominal ultrasound being the first-line imaging modality due to its wide availability, lack of radiation exposure, and good diagnostic accuracy. 1

Clinical Evaluation

• History: Key features include right upper quadrant pain, fever, nausea, vomiting, and food intolerance 1
• Physical examination: Look for right upper quadrant tenderness and Murphy's sign (pain on inspiration during palpation of the right upper quadrant) 1
• No single clinical or laboratory finding has sufficient diagnostic power to establish or exclude cholecystitis 1

Laboratory Testing

• Complete blood count: Elevated white blood cell count is common 1, 2
• C-reactive protein: Elevation suggests inflammation 1
• Liver function tests: May be elevated but not specific for cholecystitis; helpful to assess for potential common bile duct stones 1, 3

Imaging Studies

First-Line Imaging

• Abdominal ultrasound: Should be performed first in all patients with suspected cholecystitis 1
  • Look for: gallstones, gallbladder wall thickening, pericholecystic fluid, and sonographic Murphy's sign 1
  • Sensitivity: 81% (range 50-100%), Specificity: 83% (range 33-100%) 1
  • Advantages: widely available, non-invasive, no radiation exposure, cost-effective 1

Second-Line Imaging (for equivocal cases)

• Hepatobiliary iminodiacetic acid (HIDA) scan: Highest sensitivity (97%) and specificity (90%) for cholecystitis 1

  • Indicated when ultrasound findings are equivocal 1
  • Non-visualization of the gallbladder suggests cystic duct obstruction 2, 4

• MRI: Similar accuracy to ultrasound but more expensive 1

  • Consider in patients with equivocal ultrasound findings or to better visualize hepatic and biliary abnormalities 1, 4

• CT scan: Limited role in primary diagnosis of cholecystitis 1

  • May be useful for evaluating complications or for surgical planning 1, 5
  • Better for identifying complications like emphysematous, gangrenous, or perforated cholecystitis 5, 4

Diagnostic Algorithm

1. Initial assessment: History, physical examination, and laboratory tests 1
2. First-line imaging: Abdominal ultrasound 1
3. If ultrasound is inconclusive:
   • HIDA scan (preferred second-line test) 1
   • Alternative: MRI if available 1
4. If complications are suspected: Consider CT scan 1, 5

Pitfalls and Caveats

• Ultrasound findings can be operator-dependent and may have significant heterogeneity in diagnostic performance 1
• Sonographic Murphy's sign has relatively low specificity and may be unreliable if the patient has received pain medication prior to imaging 1, 4
• In critically ill patients, gallbladder abnormalities on ultrasound may be present without acute cholecystitis 1, 5
• Acalculous cholecystitis (5-10% of cases) may be more difficult to diagnose and typically occurs in critically ill patients 2, 6
• Early diagnosis is crucial as complications (gangrenous, emphysematous, perforated cholecystitis) increase morbidity and mortality 5, 4