BAL sensitivity and specificity in interstitial pneumonia

ABSTRACT

Introduction and Purpose of the study The sensitivity of genomic tests to identify SARS-CoV2 is around 65-75%. It is very common to find clinical and radiological pictures suggestive of infection but with a negative nasopharyngeal swab. The aim of our study was to use BAL fibrobronchoscopy in subjects with negative swab but with clinical and radiological signs suggesting SARS-CoV2 infection. Materials and Methods: 52 subjects admitted to the observation area (gray area) Covid of the F. Miulli Hospital in 2020 were examined. All had negative nasopharyngeal swab (even in several determinations), also performed on sputum, but a clinical and radiological picture (Ground Glass Opacity with or without consolidations) suggestive of infection. In all subjects a fibrobronchoscopy with BAL was performed with the microbiological research also of bacteria and other viruses (pneumo plus film array). The examination was performed about 10 days after the onset of symptoms. Results: The BAL allowed microbiological diagnosis (Covid and non-Covid) in 30.8% of cases, while the positivity rate for SARSCoV 2 was 11.5%. Conclusions: Our data shows that the negativity of BAL in the search for the SARS-CoV 2 virus agrees with the outcome of the nasopharyngeal and sputum swab (89.5%), highlighting 11.5% of positive subjects. However, BAL negativity does not exclude SARS-CoV2 etiology, especially in typical radiological cases. The time interval between the onset of infection and BAL may have allowed the clearance of the virus.