What is the best test for detecting cholecystitis (inflammation of the gallbladder)?

From the Guidelines

The best initial test for detecting cholecystitis is an ultrasound of the right upper quadrant of the abdomen. This non-invasive imaging study should be the initial diagnostic test of choice as it offers high sensitivity and specificity for acute cholecystitis, and is recommended by recent guidelines 1. During the ultrasound, the technician will look for specific findings such as gallbladder wall thickening, pericholecystic fluid, gallstones, and a sonographic Murphy's sign.

Key Findings

• Ultrasound is the first choice of investigation for biliary symptoms or right upper quadrant abdominal pain, as stated in the ACR Appropriateness Criteria 1.
• The usefulness of US is limited in critically ill patients where gallbladder abnormalities are common in the absence of acute cholecystitis 1.
• If complicated cholecystitis is suspected, US remains the first choice of investigation, but its sensitivity to some complications of cholecystitis is often limited 1.
• A normal appearance of the gallbladder, especially the wall, makes acute gallbladder pathology very unlikely, as noted in the ACR Appropriateness Criteria 1.

Diagnostic Approach

• If ultrasound results are inconclusive but clinical suspicion remains high, a hepatobiliary iminodiacetic acid (HIDA) scan should be performed as the next step, as it has high sensitivity and specificity for acute cholecystitis 1.
• CT scans and MRI can also detect cholecystitis but are generally reserved for cases where complications are suspected or when the diagnosis remains unclear after initial testing, as recommended by the Infectious Diseases Society of America 1.

Recommendations

• The Infectious Diseases Society of America suggests abdominal US as the initial diagnostic imaging modality for non-pregnant adults with suspected acute cholecystitis or acute cholangitis, with a conditional recommendation and very low certainty of evidence 1.
• CT, MRI/MRCP, or HIDA may be obtained for subsequent imaging if initial imaging is inconclusive, as stated in the guidelines 1.

From the Research

Diagnostic Tests for Cholecystitis

• The best test for detecting cholecystitis is a topic of ongoing debate, with various studies suggesting different diagnostic approaches 2, 3, 4, 5, 6.
• Ultrasound (US) is often considered the first-line diagnostic test for evaluating gallstone disease and diagnosing acute cholecystitis (AC) 2, 4, 5.
• However, computed tomography (CT) has been shown to be more sensitive than US for diagnosing AC, particularly in patients without typical clinical signs of AC 2.
• Hepato-imino diacetic acid (HIDA) scan has also been found to be highly sensitive for diagnosing AC, with a sensitivity of 91.7% compared to 73.3% for US 3.
• The combination of US and HIDA scan has been shown to have a high sensitivity for diagnosing AC, ranging from 90% to 97.7% 3, 6.

Comparison of Diagnostic Tests

• A study published in 2015 found that CT was more sensitive than US for diagnosing AC, with a sensitivity of 92% compared to 79% for US 2.
• Another study published in 2014 found that HIDA scan was more sensitive than US for diagnosing AC, with a sensitivity of 91.7% compared to 73.3% for US 3.
• A study published in 2001 found that the combination of US and HIDA scan had a sensitivity of 90% for diagnosing AC, compared to 48% for US alone and 86% for HIDA scan alone 6.

Clinical Recommendations

• Ultrasound is recommended as the initial imaging choice for detecting gallstones and acute cholecystitis 5.
• A HIDA scan can be used to evaluate for cholecystitis in patients with negative or equivocal ultrasound findings 5.
• Computed tomography can be used as a diagnostic test for AC, particularly in patients without typical clinical signs of AC 2.