Purpose: The aim of this study was to identify and classify the ultrasonographic and computed tomography (CT) signs of simple and complicated acute cholecystitis and to define the correct diagnostic protocol.
Materials and methods: We retrospectively reviewed 35 patients (23 men and 12 women; mean age 66.6 years) presenting with acute cholecystitis who were assessed by emergency ultrasonography (US) (30/35 cases) and spiral CT (12/35 cases); all patients underwent emergency surgery. The US signs were analysed and classified as major criteria (wall thickening and stratification, distension, Murphy's sign), minor criteria (bile stones, sludge, and biliary tract dilatation), and complication signs (gas collections, aerobilia, fluid collection, difficult or missed identification of the gallbladder). Imaging results were compared with histological findings (gold standard), and accuracy, sensitivity, specificity, and positive and negative predictive values (PPVs and NPVs) were assessed for each modality. Concordance between the US and CT findings was also evaluated for cases undergoing both examinations; additional findings provided by one or the other modality were also assessed.
Results: US had an accuracy of 66.6%, a sensitivity of 37.5%, a specificity of 70%, a PPV of 100%, and an NPV of 58.3%. CT had 100% accuracy, sensitivity, and specificity. Concordance between US and CT was observed for diagnosis of complications, but CT provided additional findings in all cases. The majority of complicated cases undergoing US examination (68.7%) revealed more than two major criteria and one minor criterion or at least one sign of complication.
Conclusions: If more than two major signs associated with one minor sign or at least one sign of complication are present at US, CT is mandatory to recognise and thoroughly evaluate the type of complication and indicate appropriate treatment.