CT Abdomen/Pelvis for Positive Murphy Sign
A positive Murphy sign alone does NOT warrant CT imaging—ultrasound is the appropriate first-line imaging modality for suspected acute cholecystitis. 11
Recommended Diagnostic Approach
The 2020 World Society of Emergency Surgery guidelines explicitly state that no single clinical finding, including Murphy's sign, has sufficient diagnostic power to establish or exclude acute calculus cholecystitis 1. Murphy's sign has a modest positive likelihood ratio of only 2.8 (95% CI 0.8–8.6), meaning it provides limited diagnostic certainty on its own 1.
First-Line Imaging: Ultrasound
For patients presenting with a positive Murphy sign:
- Ultrasound is the initial imaging modality of choice 2
- Biliary scintigraphy (HIDA scan) serves as an alternative first-line option 2
- These modalities effectively evaluate for gallstones, wall thickening, pericholecystic fluid, and sonographic Murphy sign
When CT Becomes Indicated
CT abdomen/pelvis should be reserved for specific clinical scenarios:
Suspected complicated cholecystitis when ultrasound findings are equivocal or suggest advanced disease:
- Concern for gangrenous cholecystitis
- Suspected gallbladder perforation
- Need to identify mural devascularization or wall discontinuity 3
Fever with negative Murphy sign - this combination warrants ultrasound PLUS contrast-enhanced CT to evaluate for alternative diagnoses 2
Ultrasound limitations - when ultrasound cannot adequately visualize the gallbladder or when clinical suspicion remains high despite negative ultrasound
Clinical Reasoning
The diagnostic strategy should integrate multiple parameters rather than relying on Murphy's sign alone 11:
- Clinical features: Right upper quadrant pain, fever, vomiting
- Laboratory tests: Elevated WBC (particularly neutrophil count), elevated CRP
- Risk stratification: Age ≥60 years, male sex, and leukocytosis significantly increase acute cholecystitis probability 4
Recent data shows that combining sonographic Murphy sign with age, sex, and WBC count effectively stratifies patients into distinct risk groups—with high-risk patients having a 43.1% rate of acute cholecystitis versus 1.8% in low-risk patients 4.
Critical Pitfalls to Avoid
- Do not skip ultrasound and proceed directly to CT based solely on Murphy's sign—this exposes patients to unnecessary radiation and cost
- Consider alternative diagnoses when imaging doesn't support cholecystitis, particularly Fitz-Hugh-Curtis syndrome in women with sexual history and vaginal discharge 5
- Recognize CT's superior value lies in detecting complications (gangrene, perforation, abscess) rather than making the initial diagnosis of uncomplicated cholecystitis 3
In summary: Start with ultrasound for positive Murphy sign; escalate to CT only when complicated disease is suspected or ultrasound is non-diagnostic.