Comparison of Number of Passes and Cytopathological Specimen Adequacy for Thyroid Fine-Needle Aspiration Biopsy in the Absence of an On-Site Pathologist

Aim: Ultrasound-guided fine-needle aspiration biopsy (FNAB) is a reliable, minimally invasive diagnostic method with high sensitivity and specificity in the evaluation of thyroid nodules. Our aim in this retrospective study was to determine if there was a difference in the adequacy ratio based on the number of needle passes in the thyroid FNABs in the absence of rapid on-site evaluation (ROSE) by the pathologist and to determine the optimal needle pass number for FNAB. Methods: Between November 2018 and February 2019, thyroid FNABs of 121 (99 female, 22 male) patients were evaluated retrospectively. Samples for each biopsy were numbered according to the order of retrieval, and 4 pairs of slides were prepared by the radiologist without on-site microscopic evaluation. Cytological results were determined according to the Bethesda classification. Results: The rate of adequacy in the first, second, third, and fourth passes were 76.0, 82.6, 77.7, and 71.2%, respectively. No statistically significant difference was found between these four groups in terms of adequacy (p = 0.21). The adequacy rates of the 1st, 1st+2nd, 1st+2nd+3rd, and cumulative evaluation of all four biopsies were 76.0, 87.6, 90.1, and 91.7%, respectively (p = 0.001). A statistically significant difference was found in the comparison of the 1st biopsy and the cumulative 1st+2nd biopsy in terms of adequacy rates (p = 0.019). However, there was no statistically significant difference between the cumulative 1st+2nd biopsy and the cumulative 1st+2nd+3rd biopsy in terms of adequacy rates (p = 0.54). Conclusions: In cases where ROSE cannot be performed, we recommend a minimum of 2 and a maximum of 3 needle entries for FNAB adequacy with the right technique and preparation.