Ultrasound-guided fine needle aspiration of thyroid nodules with on-site cytological examination: Diagnostic efficacy, prevalence, and factors predicting for Bethesda category I results

Abstract

Background and objectiveUltrasound-guided fine needle aspiration of thyroid nodules with on-site cytological examination may decrease the number of Bethesda category I cytologies. The study objective was to evaluate our second-year experience with this procedure to analyze diagnostic efficacy, prevalence, and factors predicting for Bethesda category I results. Patients and methodA retrospective study was conducted of 279 nodules from 233 patients. Ultrasound-guided fine needle aspiration was performed according to the 2015 criteria of the American Thyroid Association. A specimen of each aspiration was air-fixed on site before Diff-Quik staining and microscopic examination to assess its suitability; otherwise, nodule aspiration was repeated up to 5 times. Diagnostic efficacy was assessed based on sensitivity and specificity on the cytological categories Bethesda II and Bethesda VI. ResultsDiagnostic sensitivity and specificity were both 100%, 5.4% Bethesda category I results were obtained, and variables independently associated were age (4.7% increase per year of life) and nodule volume (2.3% increase per each 1ml of volume). ConclusionsUltrasound-guided fine needle aspiration of thyroid nodules with on-site cytological examination allows for a high diagnostic efficacy and has been shown to be a highly relevant procedure because it has a very low rate of cytological results of Bethesda category I, whose risk has been higher in older subjects and with larger nodules.