Agreement between point-of-care ultrasonography and the Tokyo guidelines 2018 for acute cholecystitis (PACED study).

Abstract

Objective: To evaluate the agreement and diagnostic accuracy of abdominal point-of-care ultrasonography (PoCUS) performed by emergency physicians for suspected acute cholecystitis, using the Tokyo Guidelines 2018 (TG18) as the reference standard.

Methods: We conducted a multicenter, diagnostic accuracy study at two university-affiliated tertiary care hospitals in Thailand from October 2019 to June 2024. We included adult patients presenting to the emergency department (ED) with suspected acute cholecystitis who underwent PoCUS by an emergency physician, followed by confirmatory radiological imaging (formal ultrasonography or computed tomography; CT). A positive PoCUS was defined as the presence of gallstones plus a sonographic Murphy's sign, gallbladder wall thickening > 3 mm, or pericholecystic fluid. Blinded reviewers adjudicated the final diagnosis based on the comprehensive TG18 criteria. The primary outcome was the diagnostic agreement between the PoCUS result and the final TG18 diagnosis, measured using Cohen's kappa (κ). Secondary outcomes included sensitivity, specificity, predictive values, and likelihood ratios. The study was reported in accordance with the STARD 2015 guidelines.

Results: According to TG18 criteria, 537 patients (68.6%) were diagnosed with acute cholecystitis. PoCUS demonstrated a sensitivity of 86.6% (95% CI, 83.4-89.4) and a specificity of 17.1% (95% CI, 12.5-22.5). The positive predictive value (PPV) was 70.0%, the negative predictive value (NPV) was 37.0%, and the overall diagnostic accuracy was 64.9%. Among individual PoCUS signs, only gallstones were significantly associated with TG18-confirmed cholecystitis (p < 0.01).

Conclusion: In this large, real-world cohort, PoCUS performed by emergency physicians showed poor agreement with the definitive TG18 diagnosis of acute cholecystitis. Although sensitive, its extremely low specificity resulted in a high number of false positives, limiting its usefulness as a standalone diagnostic tool. These findings highlight the importance of combining PoCUS findings with clinical and laboratory data, as recommended by the TG18, to prevent diagnostic errors and unnecessary further testing.