Contribution of ultrasonography and cholescintigraphy to the diagnosis of acute acalculous cholecystitis in intensive care unit patients

Abstract

Objectives: To assess the respective value of ultrasonography (US) and morphine cholescintigraphy (MC) in the diagnosis of acute acalculous cholecystitis (AAC)

Design and setting: Prospective study in an intensive care unit of a university hospital

Patients and intervention: Twenty-eight patients with clinically and biologically suspected of AAC. US was performed at the bedside and less than 12 h later MC. US was considered positive if three major criteria were present: wall thickness greater than 4 mm, hydrops, sludge; MC results were regarded as positive if the gallbladder could not be visualized. These latter patients underwent cholecystectomy and the diagnosis of AAC was confirmed through histopathological study.

Measurements and main results: Sensitivity of US and MC, respectively, was 50% and 67%, specificity 94% and 100%, positive predictive value 86% and 100%, negative predictive value 71% and 80%, and accuracy 75% and 86%. The correlation between US and MC findings was 71%, with κ=0.31. By Bayesian analysis the probability of disease if the MC finding was positive was 100% regardless of US results. A positive US finding was associated with a 86% probability of disease, but with a probability of only 66% in case of negative MC results. MC is thus superior to US for confirming AAC in selected critically ill patients. Nevertheless, US is an easy, noninvasive, and effective method of bedside screening. The combination of the two imaging tests improves diagnostic accuracy and reduces false-positive and false-negative rates. Poor agreement between the two tests leads to better diagnostic complementarity.