Total number of biopsies needed during bronchoscopy for diagnosing pulmonary lesions

<bold>Abstract of preliminary data</bold> <bold>Background:</bold> Biopsies samples through transbronchial bronchoscopy is frequently preferred for fragile patients with potentially malignant lung lesions due to its low complication rate, although its diagnostic yield is lower than that of other invasive procedures. However, the optimal number of biopsies is inadequately known. This study aimed to identify the optimal number of biopsies by comparing the diagnostic yields of 5, 10, and 15 biopsies. <bold>Methods:</bold> This prospective cohort study included 85 patients referred for transbronchial biopsies via bronchoscopy. Biopsies were collected from 71 patient, and they were sampled in three containers, each containing five biopsies. A pathologist evaluated whether the biopsies were representative for lung mass, diagnostic for malignancy, and if the tissue was sufficient for analyses by immunohistochemistry and Next Generation Sequencing. <bold>Results:</bold> The diagnostic yield was 52.1%, 59.2%, and 66.2% for 5, 10, and 15 biopsies, respectively. The difference in diagnostic yield comparing 5 and 15 biopsies had an insignificant p-value of 0.088. and was insignificant. <bold>Conclusion:</bold> We found a non-significant difference in the diagnostic yield when sampling 10 or 15 biopsies compared to 5. We could, however, report a higher number of diagnostic biopsies when sampling at least 10, as this led to the greatest increase in the number of malignant biopsies and yield. Therefore, this study suggests sampling at least 10 biopsies during a transbronchial bronchoscopy procedure in suspected malignancies to ensure sufficient tissue for diagnosis and tumour marker testing.