What is the sensitivity and specificity of computed tomography (CT) scan versus ultrasonography for diagnosing acute cholecystitis?

From the Guidelines

For acute cholecystitis, ultrasound is the preferred initial imaging modality due to its high sensitivity of 81% and specificity of 83%, as well as its lack of radiation, lower cost, and wide availability, as reported in the 2020 World Society of Emergency Surgery guidelines 1. The sensitivity and specificity of computed tomography (CT) scan versus ultrasonography for diagnosing acute cholecystitis have been evaluated in several studies.

• The 2020 World Society of Emergency Surgery guidelines report a sensitivity of 81% and specificity of 83% for ultrasonography 1.
• In contrast, the 2024 Clinical Practice Guideline update by the Infectious Diseases Society of America reports a sensitivity of 73% and specificity of 94% for CT scan, although only one study was included in the analysis 1.
• The 2019 ACR Appropriateness Criteria report a sensitivity of 88% and specificity of 80% for ultrasonography, and a sensitivity of 97% and specificity of 90% for cholescintigraphy, although cholescintigraphy is not as widely available as ultrasonography 1.
• The 2015 American Family Physician report a sensitivity of 81% and specificity of 83% for ultrasonography, and notes that CT scan may be considered in patients with inconclusive ultrasonography or cholescintigraphy results 1. Overall, ultrasound is the preferred initial imaging modality for suspected acute cholecystitis due to its high accuracy, lack of radiation, lower cost, and wide availability. CT scan may be reserved for cases where ultrasound results are equivocal or when complications such as perforation or abscess formation are suspected.
• The choice between these imaging modalities should consider the clinical presentation, with ultrasound being the standard initial approach for suspected acute cholecystitis due to its favorable diagnostic performance and safety profile.
• It is essential to note that the diagnostic performance of ultrasonography and CT scan may vary depending on the specific clinical context and patient population.
• However, based on the most recent and highest-quality evidence, ultrasound remains the preferred initial imaging modality for suspected acute cholecystitis 1.

From the Research

Sensitivity and Specificity of CT Scan versus Ultrasonography

• The sensitivity of computed tomography (CT) scan for diagnosing acute cholecystitis is 92% 2, which is higher than that of ultrasonography (79%) 2.
• Ultrasonography has a sensitivity of 81% and a specificity of 83% for diagnosing acute cholecystitis 3.
• A study found that the sensitivity of ultrasonography for cholecystitis was lower than previously reported at 75.7% for acute cholecystitis, 34.6% for chronic cholecystitis, and 42.7% overall 4.
• The sensitivity of ultrasonography for acute cholecystitis was found to be 54% in another study, with a specificity of 81% 5.
• Cholescintigraphy has a sensitivity of 96% and a specificity of 90% for diagnosing acute cholecystitis 3, and is more sensitive than ultrasonography for this purpose 6.
• The combination of ultrasonography and cholescintigraphy has a sensitivity of 90% for diagnosing acute cholecystitis 6.

Comparison of CT Scan and Ultrasonography

• CT scan is more sensitive than ultrasonography for diagnosing acute cholecystitis 2.
• Ultrasonography is more sensitive than CT scan for identifying cholelithiasis (87% versus 60%) 2.
• CT scan is often used in patients without typical clinical signs of acute cholecystitis 2.
• Ultrasonography is the preferred modality for diagnosing acute cholecystitis due to its safety, availability, and cost-effectiveness 3.