Chulalongkorn Medical Journal


Background: The major problem of conventional smear for ultrasound-guided fine needle aspiration (FNA) of thyroid nodules is the sample inadequacy. Liquid-based cytology (LBC) is claimed to perform better than the conventional smear (CS) in reducing sample inadequacy. However, the evidence of better adequacy in LBC is unclear. Objective: This study is the first prospective study aiming to compare sample adequacy in CS and LBC using ThinPrep system with adequacy criteria based on the 2017 Bethesda System for Reporting Thyroid Cytopathology. Methods: One hundred and twenty thyroid nodules were prospectively recruited for ultrasound-guided FNA from March to September 2019. The sample from each nodule was prepared in both CS and LBC using a randomised needle size between 25 or 23G. The cytological adequacy for each method was reviewed by only one pathologist. Results: There was no significant difference in adequacy rate between the CS and LBC group (57.5% vs. 53.3%, P = 0.371). Univariate and multivariate analysis showed only two factors to be significantly associated with adequacy, including the presence of internal vascularity on ultrasound (adjusted RR = 1.3, P = 0.038) and the use of 25G needles compared with 23G needles (adjusted RR = 1.4, P = 0.013). Conclusion: This prospective study did not demonstrate the superiority of LBC over CS. The presence of internal vascularity on ultrasound is a potential predictor of FNA adequacy. The use of a 25G needle may be recommended rather than a 23G needle in thyroid FNA.


Faculty of Medicine, Chulalongkorn University



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