What is the diagnostic approach for cholecystitis?

Diagnostic Approach for Cholecystitis

Initial Diagnostic Strategy

Begin with abdominal ultrasound as the first-line imaging modality for all non-pregnant adults with suspected acute cholecystitis, as it provides good diagnostic accuracy (sensitivity 81%, specificity 83%) without radiation exposure. 1

The diagnosis requires integration of clinical presentation, laboratory findings, and imaging confirmation—no single finding is sufficient to establish or exclude cholecystitis. 2, 3

Clinical Assessment

Look for these specific clinical features:

• Right upper quadrant pain and tenderness (negative likelihood ratio 0.4 when absent) 4, 3
• Murphy's sign (inspiratory arrest during RUQ palpation; positive likelihood ratio 2.8) 2, 5, 3
• Fever (systemic inflammatory response) 2, 5
• Nausea, vomiting, or food intolerance 2, 5
• Palpable RUQ mass (in advanced cases) 2

Laboratory Evaluation

Order these tests to support the diagnosis:

• Complete blood count: Elevated white blood cell count (neutrophil count has 70% sensitivity, 65.8% specificity) 2
• C-reactive protein: Elevation indicates inflammation 2, 5
• Liver function tests: Helpful to assess for common bile duct stones, though not specific for cholecystitis 5

Imaging Algorithm

Step 1: Initial Imaging

Perform abdominal ultrasound first in all patients with suspected cholecystitis. 1, 5

Look for these ultrasound findings:

• Gallstones 5
• Gallbladder wall thickening 5
• Pericholecystic fluid 5
• Sonographic Murphy's sign 5

Step 2: If Ultrasound is Equivocal

Obtain CT scan with IV contrast if ultrasound is non-diagnostic but clinical suspicion persists (sensitivity 92-93.4%). 1, 4

CT is preferable with IV contrast and helps evaluate for complications or surgical planning. 1, 6

Step 3: If Both Ultrasound and CT are Equivocal

Proceed to either HIDA scan or MRI/MRCP if both prior studies are inconclusive and clinical suspicion remains high. 1

• HIDA scan (hepatobiliary scintigraphy) is the gold standard with highest sensitivity (97%) and specificity (90%) for cholecystitis 5, 7, 8
• MRI/MRCP is a reasonable alternative with similar accuracy to ultrasound but higher cost 5, 4

Special Populations

Pregnant Patients

Either ultrasound or MRI can be used as initial imaging, though guidelines cannot definitively recommend one over the other due to knowledge gaps. 1

Avoid radiation-based imaging when possible. 5

Children

Mirror the adult imaging pathway (ultrasound → CT → HIDA/MRI), as acute cholecystitis is uncommon in children and specific pediatric evidence is limited. 1

Diagnostic Criteria Framework

The Tokyo Guidelines provide a structured approach requiring:

• One local sign: Murphy's sign, mass/pain/tenderness in RUQ 4, 9
• One systemic sign: Fever, elevated WBC, elevated CRP 4, 9
• Imaging confirmation 4, 9

This framework has 60.3% overall accuracy. 4

Critical Pitfalls to Avoid

Do not rely on clinical impression alone—experienced clinicians achieve a positive likelihood ratio of 25-30 for diagnostic impression, but this still requires imaging confirmation. 3

Do not skip imaging even with classic presentation—combinations of symptoms and signs improve diagnostic accuracy, but ultrasound remains essential for confirmation. 3, 7

Distinguish acute cholangitis from cholecystitis—cholangitis requires the additional triad of jaundice, fever/chills/RUQ pain, laboratory evidence of biliary stasis, and imaging showing biliary dilatation or obstructing pathology (stricture, stone, mass). 1, 4

Stratify patients for common bile duct stones based on clinical, laboratory, and imaging findings—high-risk patients need preoperative ERCP, while moderate-risk patients require second-level examinations (MRCP, EUS, or intraoperative cholangiography). 2