Comparing accuracy of bedside ultrasound examination with physical examination for detection of pleural effusion

Background: In detecting pleural effusion, bedside ultrasound (US) has been shown to be more accurate than auscultation. However, US has not been previously compared to the comprehensive physical examination. This study seeks to compare the accuracy of physical examination with bedside US in detecting pleural effusion. Methods: This study included a convenience sample of 34 medical inpatients from Calgary, Canada and Spokane, USA, with chest imaging performed within 24 h of recruitment. Imaging results served as the reference standard for pleural effusion. All patients underwent a comprehensive lung physical examination and a bedside US examination by two researchers blinded to the imaging results. Results: Physical examination was less accurate than US (sensitivity of 44.0% [95% confidence interval (CI) 30.0-58.8%], specificity 88.9% (95% CI 65.3-98.6%), positive likelihood (LR) 3.96 (95% CI 1.03-15.18), negative LR 0.63 (95% CI 0.47-0.85) for physical examination; sensitivity 98% (95% CI 89.4-100%), specificity 94.4% (95% CI 72.7-99.9%), positive LR 17.6 (95% CI 2.6-118.6), negative LR 0.02 (95% CI 0.00-0.15) for US). The percentage of examinations rated with a confidence level of 4 or higher (out of 5) was higher for US (85% of the seated US examination and 94% of the supine US examination, compared to 35% of the PE, P < 0.001), and took less time to perform (P < 0.0001). Conclusions: US examination for pleural effusion was more accurate than the physical examination, conferred higher confidence, and required less time to complete.