What is the diagnostic approach for cholecystitis?

Diagnostic Approach for Cholecystitis

The diagnosis of cholecystitis requires a combination of detailed history, complete clinical examination, laboratory tests, and imaging investigations, as no single clinical or laboratory finding has sufficient diagnostic power to establish or exclude the diagnosis. 1, 2

Clinical Evaluation

• Right upper quadrant pain or tenderness is a key clinical feature but has limited diagnostic value alone (negative LR 0.4; 95% CI 0.2-1.1) 1
• Murphy's sign (pain on inspiration during palpation of the right upper quadrant) is the most useful clinical finding (positive LR 2.8; 95% CI 0.8-8.6) but still insufficient for definitive diagnosis 1, 3
• Fever, nausea, vomiting, and food intolerance are common symptoms that should raise suspicion 1, 2
• No single clinical finding has sufficient diagnostic power to rule in or rule out cholecystitis 1, 3, 4

Laboratory Testing

• Elevated white blood cell count suggests inflammation but is not specific for cholecystitis 1, 2
• Elevated C-reactive protein is a useful inflammatory marker 1, 2
• Liver function tests may be elevated but have limited specificity; neutrophil count has been shown to have 70% sensitivity and 65.8% specificity 1, 2
• Elevated bilirubin has high specificity (93%) but low sensitivity (40%) 5

Imaging Studies

• Abdominal ultrasound should be performed as the first-line imaging test in all patients with suspected cholecystitis, with a sensitivity of approximately 81% and specificity of 83% 2, 4, 5
• Ultrasound findings to look for include gallstones, gallbladder wall thickening, pericholecystic fluid, and sonographic Murphy's sign 2, 4
• If ultrasound results are equivocal, hepatobiliary iminodiacetic acid (HIDA) scan is recommended as the second-line imaging test, with the highest sensitivity (97%) and specificity (90%) for cholecystitis 2, 4
• MRI may be considered in patients with equivocal ultrasound findings or to better visualize hepatic and biliary abnormalities 2, 6
• CT scan has a limited role in primary diagnosis of cholecystitis but may be useful for evaluating complications or for surgical planning 2, 6

Diagnostic Algorithm

1. Initial assessment:

   • Detailed history focusing on right upper quadrant pain, fever, nausea, vomiting 1, 2
   • Physical examination with attention to right upper quadrant tenderness and Murphy's sign 1
   • Laboratory tests including complete blood count, C-reactive protein, and liver function tests 1, 2

2. Imaging:

   • First-line: Abdominal ultrasound 2, 4
   • If ultrasound is inconclusive but clinical suspicion remains high: HIDA scan 2, 4
   • Alternative second-line options: MRI or CT scan (particularly if complications are suspected) 2, 6

3. Diagnosis confirmation:

   • Diagnosis is confirmed when clinical findings are supported by imaging studies 1, 7
   • The Tokyo Guidelines criteria include a combination of clinical signs, laboratory tests, and imaging features 1, 7

Common Pitfalls and Caveats

• Relying on a single clinical or laboratory finding can lead to misdiagnosis 1, 3
• The accuracy of the Tokyo Guidelines criteria has been questioned, with one study showing only 60.3% overall accuracy 1
• Acalculous cholecystitis (without gallstones) accounts for 5-10% of cases and may be more difficult to diagnose 4
• Elderly patients may present with atypical symptoms, making diagnosis more challenging 4
• Delayed diagnosis can lead to increased morbidity and mortality due to complications such as perforation, abscess formation, or sepsis 6, 4