What is the best test for diagnosing cholecystitis?

From the Guidelines

The best test for diagnosing cholecystitis is an ultrasound of the right upper quadrant of the abdomen. This imaging modality offers high sensitivity and specificity for detecting gallbladder inflammation, gallstones, and wall thickening, which are hallmark findings in cholecystitis 1. Ultrasound should be performed as the initial imaging test when cholecystitis is suspected based on clinical symptoms such as right upper quadrant pain, fever, and Murphy's sign. The test is widely available, non-invasive, does not use radiation, and is relatively inexpensive compared to other imaging modalities.

Key Points to Consider

• Ultrasound is the first-line imaging test for suspected cholecystitis due to its high sensitivity and specificity, as well as its non-invasive nature and lack of radiation exposure 1.
• If ultrasound results are equivocal but clinical suspicion remains high, a hepatobiliary iminodiacetic acid (HIDA) scan can be performed as a follow-up test, which has even higher sensitivity for acute cholecystitis by demonstrating non-filling of the gallbladder 1.
• CT scans may be useful in complicated cases or when other diagnoses are being considered, but they are not the first-line imaging test for suspected cholecystitis 1.
• The diagnosis of acute cholecystitis should be based on a combination of clinical symptoms, laboratory findings, and imaging results, rather than relying solely on imaging tests 1.

Additional Considerations

• The use of point shear-wave elastography (pSWE) and superb microvascular imaging (SMI) may improve the diagnostic accuracy of ultrasound for acute cholecystitis, but these techniques require expertise and have limited external validity 1.
• MRI and MRCP may be useful in evaluating the hepatobiliary system and identifying complications of cholecystitis, but they are not the first-line imaging tests for suspected cholecystitis 1.

Recommendation

Ultrasound should be the initial imaging test for suspected cholecystitis, due to its high sensitivity and specificity, non-invasive nature, and lack of radiation exposure 1. If ultrasound results are equivocal, a HIDA scan or CT scan may be performed as a follow-up test, depending on the clinical suspicion and the presence of complications.

From the Research

Diagnostic Tests for Cholecystitis

The diagnosis of cholecystitis can be made using various imaging tests, including ultrasound, computed tomography (CT), and hepato-imino diacetic acid (HIDA) scan. The choice of test depends on the clinical presentation and the availability of resources.

Comparison of Diagnostic Tests

• Ultrasound is commonly used as the first-line diagnostic test for cholecystitis, with a sensitivity of 75.7% to 98.6% 2, 3.
• CT scan has been shown to be more sensitive than ultrasound in some studies, with a sensitivity of 92% to 93.4% 4, 3.
• HIDA scan has been shown to be more sensitive than ultrasound, with a sensitivity of 86% to 91.7% 5, 6.
• The combination of ultrasound and HIDA scan has been shown to have a high sensitivity of 90% to 97.7% 5, 6.

Specific Signs on Imaging Tests

• Ultrasound is more sensitive in detecting cholelithiasis and a thickened gallbladder wall, with a sensitivity of 95.9% and 92.3%, respectively 3.
• CT scan is more sensitive in detecting pericholecystic fluid and gallbladder distension, with a sensitivity of 83.6% and 95.7%, respectively 3.

Clinical Implications

• The choice of diagnostic test should be based on the clinical presentation and the availability of resources.
• Ultrasound should continue to be the first-line imaging modality in patients suspected of having cholecystitis, especially in a community emergency department setting 3.
• CT scan and HIDA scan can be used as additional diagnostic tests in patients with suspected cholecystitis, especially in cases where ultrasound is inconclusive or unavailable 4, 5, 6.