Diagnostic Approach to RUQ Pain with Negative Ultrasound

Initial Evaluation and Imaging

The American College of Radiology recommends obtaining a hepatobiliary scintigraphy (HIDA scan) if clinical suspicion for acute cholecystitis remains high after a negative ultrasound, or proceeding to CT abdomen with IV contrast to evaluate for alternative diagnoses and complications 1, 2, 3
The Infectious Diseases Society of America (IDSA) guidelines recommend CT as the next imaging modality when initial ultrasound is equivocal or non-diagnostic, with a sensitivity of 97% and specificity of 90% for acute cholecystitis 1, 2

CT abdomen with IV contrast can identify complications including gangrene, perforation, gas formation, and adjacent liver parenchymal hyperemia, with a strength of evidence rated as high 4, 3
The Journal of the American College of Radiology recommends considering alternative diagnoses such as hepatic pathology, pancreatic inflammation, renal pathology, gastrointestinal disorders, and thoracic processes, with a moderate level of evidence 4, 5, 2
MRI/MRCP has 85-100% sensitivity for cholelithiasis and choledocholithiasis, and can distinguish acute from chronic cholecystitis based on T2 signal characteristics and wall enhancement patterns, with a high level of evidence 4, 3

The American College of Radiology advises against relying on the absence of gallbladder wall thickening to exclude acute cholecystitis, and notes that Murphy's sign has low specificity, with a moderate level of evidence 3, 6
Elevated alkaline phosphatase or bilirubin suggests biliary obstruction and warrants advanced imaging, with a high level of evidence 5
Marked leukocytosis with fever raises concern for empyema or complicated cholecystitis, with a moderate level of evidence 3
Indicators of inflammation and biliary stasis support the diagnosis of acute cholangitis, with a high level of evidence 1, 2