The incidence of pleural effusion in COVID-19 pneumonia: State-of-the-art review

BACKGROUND: COVID-19-related pleural effusions are frequently described during the ongoing pandemic. OBJECTIVES: We described the incidence, characteristics, and outcomes of COVID-19-related pleural effusions based on the current evidence available in the literature. METHODS: We searched MEDLINE, Pubmed, and Google Scholar databases using keywords of “coronavirus disease 2019 (COVID-19),” “severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2),” “pleural effusion,” “pleural fluid,” and “pleura” from January 1st, 2020 to January 31st, 2021. RESULTS: The incidence of pleural effusions was low at 7.3% among the 47 observational studies. Pleural effusions were commonly observed in critically ill patients and had Multisystem Inflammatory Syndrome (MIS). COVID-19-related pleural effusions were identified 5–7 days and 11 days, after hospital admission and onset of COVD-19 symptoms. The characteristic findings of pleural fluid were exudative, lymphocytic or neutrophilic-predominant pleural fluid with markedly elevated lactate dehydrogenase (LDH) levels and pleural fluid to serum LDH ratio. CONCLUSION: A well-designed study is required to assess the significance of COVID-19-related pleural effusions during this current pandemic.