Lung Ultrasonography for the Diagnosis of SARS-CoV-2 Pneumonia in the Emergency Department

Abstract

Study objective: Accurate diagnostic testing to identify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is critical. Although highly specific, SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) has been shown in clinical practice to be affected by a noninsignificant proportion of false-negative results. This study seeks to explore whether the integration of lung ultrasonography with clinical evaluation is associated with increased sensitivity for the diagnosis of coronavirus disease 2019 pneumonia, and therefore may facilitate the identification of false-negative SARS-CoV-2 RT-PCR results.

Methods: This prospective cohort study enrolled consecutive adult patients with symptoms potentially related to SARS-CoV-2 infection who were admitted to the emergency department (ED) of an Italian academic hospital. Immediately after the initial assessment, a lung ultrasonographic evaluation was performed and the likelihood of SARS-CoV-2 infection, based on both clinical and lung ultrasonographic findings ("integrated" assessment), was recorded. RT-PCR SARS-CoV-2 detection was subsequently performed.

Results: We enrolled 228 patients; 107 (46.9%) had SARS-CoV-2 infection. Sensitivity and negative predictive value of the clinical-lung ultrasonographic integrated assessment were higher than first RT-PCR result (94.4% [95% confidence interval {CI} 88.2% to 97.9%] versus 80.4% [95% CI 71.6% to 87.4%] and 95% [95% CI 89.5% to 98.2%] versus 85.2% [95% CI 78.3% to 90.6%], respectively). Among the 142 patients who initially had negative RT-PCR results, 21 tested positive at a subsequent molecular test performed within 72 hours. All these false-negative cases were correctly identified by the integrated assessment.

Conclusion: This study suggests that, in patients presenting to the ED with symptoms commonly associated with SARS-CoV-2 infection, the integration of lung ultrasonography with clinical evaluation has high sensitivity and specificity for coronavirus disease 2019 pneumonia and it may help to identify false-negative results occurring with RT-PCR.

Figure 1

Lung ultrasonographic scanning protocol. Areas 1, 2, 5, and 6 represent right and left anterior superior and inferior zones, respectively; areas 3, 4, 7, and 8, right and left lateral superior and inferior zones, respectively; and areas 9, 10, 11, and 12, right and left posterior superior and inferior zones, respectively.

Figure 2

Standards for Reporting Diagnostic Accuracy diagram of enrolled patients, grouped by COVID-19 infection status according to clinical and integrated assessments and RT-PCR results. C-LUS, Clinical–lung ultrasonographic integrated assessment.

Figure E1

LUS findings in COVID-19 positive patients. Panel A: irregular and thickened pleural line (arrow); Panel B: multiple small, subpleural consolidations (arrow); Panel C: B-lines and vertical artifacts (asterisks), they might be present in separate and coalescent forms and arising from a peripheral consolidations and/or from pleural points (Peng QY et al, Intensive Care Med, 2020; Volpicelli G et al, Ultrasound J, 2020).