Changes in thyroid fine needle aspiration practice during the COVID-19 pandemic

To investigate the diagnostic accuracy of a different sample preparation protocol for fine needle aspiration cytology (FNAC) of thyroid nodules established during the COVID-19 pandemic.

From April 2020, conventional smears during FNAC were ceased according to World Health Organization recommendations due to the increased infection risk for operators, and a new protocol using only liquid-based cytology (LBC) was adopted. FNACs performed between April and July 2020 (COVID-19 group) were retrospectively compared with those from December 2019 through March 2020 (Pre-COVID-19 group). The distribution of diagnoses based on SIAPEC-IAP categories and the concordance between cytological and histological results were compared using the chi-squared test.

Categories based on FNAC for 90 and 82 thyroid nodules in the Pre-COVID-19 and COVID-19 groups showed no significant difference in distribution (P = .081), with the following respective cases (and percentages): TIR1, 7 (8%) and 8 (10%); TIR1C, 0 (0%) and 6 (7%); TIR2, 59 (66%) and 55 (67%); TIR3A, 8 (9%) and 5 (6%); TIR3B, 1 (1%) and 2 (3%); TIR4, 5 (6%) and 1 (1%); and TIR5, 10 (12%) and 5 (7%). Among patients with potentially malignant lesions, surgery was performed for 12/16 (75%) nodules in the Pre-COVID-19 and 7/8 (88%) nodules in the COVID-19 groups, with no significant differences between cytological and histological diagnoses (P = .931).

The new LBC-only protocol provided similar diagnostic accuracy in comparison with conventional smears, and can be effectively applied during a viral pandemic improving operator safety.