Diagnostic Approach for Acute Cholecystitis

Diagnostic Algorithm

The American College of Radiology recommends ultrasound as the initial imaging modality for suspected acute cholecystitis, with a sensitivity of 81% and specificity of 83% 2, 3
Key ultrasound findings for acute cholecystitis include gallstones, gallbladder wall thickening, pericholecystic fluid, and sonographic Murphy's sign 1
If ultrasound results are equivocal, a HIDA scan should be performed as the next step, with a sensitivity of 97% and specificity of 90% 2, 3, 4
For pregnant patients, MRI can be considered as an alternative second-line imaging modality when ultrasound is inconclusive 2, 3

CT scan with IV contrast is recommended as subsequent imaging if complications of acute cholecystitis are suspected, such as biloma or intraabdominal abscess 2, 3
MRI/MRCP is a reasonable alternative to HIDA scan if acute cholecystitis is specifically suspected after equivocal CT, providing clearer visualization of surrounding structures 2, 3

Ultrasound sensitivity varies widely in studies, from 26% to 100%, and may be limited by abdominal tenderness and patient obesity 2, 3, 5
HIDA scan requires several hours of fasting before the procedure, which may delay diagnosis 2, 3
For pregnant patients, ultrasound or MRI should be considered as the initial diagnostic imaging modality to avoid radiation exposure 2, 3

Point shear-wave elastography (pSWE) added to conventional ultrasound may increase diagnostic accuracy, with an AUC from 79% to 96.3% 5
Superb microvascular imaging (SMI) technique may increase diagnostic accuracy of ultrasound, with an AUC from 72.9% to 85% 5