Retrospective analysis of the sonographic and computed tomographic features of gallbladder empyema

Early detection of complicated cholecystitis, particularly gallbladder empyema, is important. Yet only a handful of patients are correctly diagnosed prior to intervention. The purpose of this study was to evaluate the sonographic and computed tomography features associated with gallbladder empyema compared with the intraoperative findings and histopathological examination.

We retrospectively reviewed ultrasound and CT images for 146 patients with clinical suspicion of cholecystitis from January 2013 until December 2018. Ultrasound criteria reviewed included calculus, wall thickening, pericholecystic fluid, gallbladder distension and presence of echogenic material within the gallbladder. For CT, criteria reviewed were wall thickening, gallbladder distension, mucosal enhancement, pericholecystic fluid and hyperdense bile with an attenuation value of more than 20 HU. Association of these findings was made with intraoperative and pathological findings of 85 patients with proven gallbladder empyema.

Sonographic signs that were statistically significantly associated with gallbladder empyema (p < 0.05) were thickened gallbladder wall (mean 5.4 versus 3.0 mm), distended gallbladder (mean 8.5 versus 6.4cm), pericholecystic fluid and echogenic material within the gallbladder. No significant association between gallstones and gallbladder empyema. Scores of two and more out of four significant sonographic findings were found to have an association with higher chances of developing gallbladder empyema (p < 0.05, odds ratio: 10). None of the CT features was found to be significant with gallbladder empyema (p > 0.05).

A combination of few ultrasound features has a high significant association with gallbladder empyema. Thus, in the proper clinical setting, these findings should alarm the sonographic operator on the possibility of gallbladder empyema.