Diagnostic value of Transthoracic Ultrasonography for COVID-19 Pneumonia: A Prospective Study

Background: Corona virus infection requires early detection and precise diagnosis for an effective control in community. COVID-19 PCR is the gold standard diagnostic test having low sensitivity and adequate availability constraints. Because of high false negative rate, a large number of undetected patients remain a constant source of inadvertent disease dissemination in the community. This study was conducted to explore the diagnostic usefulness of transthoracic ultrasonography for COVID-19 pneumonia during the current pandemic. Material and Methods: This cross-sectional study was conducted in the Pulmonology OPD of Gulab Devi Teaching Hospital, Lahore-Pakistan from April 1, 2020 to July 30, 2020. A total of 237 patients with dry cough, fever and shortness of breath of sudden onset, clinically diagnosed as COVID-19 pulmonary infection, were included in the study. Patients were investigated with chest x-ray/HRCT, transthoracic ultrasonography, COVID-19 RT-PCR on nasopharyngeal samples and hematological tests. Sensitivity, Specificity, PPV (positive predictive value), NPV (negative predictive value) and diagnostic accuracy of transthoracic ultrasonography was calculated with P-value <0.05 considered as statistically significant. SPSS-26 software was used for statistical analysis. Results: Of the total 237 patients (mean age 41.23±17.5 years) presenting with complaints of a pulmonary infection, 228 were diagnosed as COVID-19 pulmonary infection by transthoracic ultrasonography and PCR.  Bilateral lesions and B-lines were the most frequent characteristic features on ultrasonography (n=237 patients; 100%). Transthoracic ultrasound diagnosed 228 patients as cases of COVID-19 pneumonia with 100% sensitivity, 66.67% specificity, 98.7% PPV, 100% NPV, and 98.73% diagnostic accuracy. Only 135 /228 (59.21%) patients were diagnosed by RT-PCR. The P-value by Fisher exact test was highly significant at 0.001 (cut-off P- value < 0.05). Conclusion: Transthoracic ultrasonography is a useful diagnostic tool with a high sensitivity, is free- from radiation exposure and capable of providing foundations for evidence based, early detection of corona virus pneumonia in a pandemic situation.