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

Objectives: To assess the respective value of ultrasonography (US) and morp hine cholescintigraphy (MC) in the diagnosis of acute acalculous cholecysti tis (AAC). Design and setting: Prospective study in an intensive care unit of a univer sity hospital. Patients and intervention: Twenty-eight patients with clinically and biolog ically 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 regarde d as positive if the gallbladder could not be visualized, These latter pati ents underwent cholecystectomy and the diagnosis of AAC was confirmed throu gh 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 10 0%, negative predictive value 71% and 80%, and accuracy 75% and 86%. The co rrelation behveen US and MC findings was 71%, with x = 0.31. By Bayesian an alysis the probability of disease if the MC finding was positive was 100% r egardless of US results. A positive US finding was associated with a 86% pr obability of disease, but with a probability of only 66% in case of negativ e MC results. MC is thus superior to US for confirming AAC in selected crit ically ill patients. Nevertheless, US is an easy, noninvasive, and effectiv e method of bedside screening. The combination of the two imaging tests imp roves diagnostic accuracy and reduces false-positive and false-negative rat es. Poor agreement between the two tests leads to better diagnostic complem entarity.