The Value of Gross Visual Assessment of Specimen Adequacy for Liquid-Based Cytology During Ultrasound-Guided, Fine-Needle Aspiration of Thyroid Nodules

Abstract

Major problems of fine-needle aspiration (FNA) of thyroid nodules arise due to nondiagnostic results caused by inadequately obtained FNA specimens. The purpose of this study was to evaluate the value of visual assessment of liquid-based cytology specimens during FNA of thyroid nodules for predicting sampling adequacy. For 3 months, visual assessment of FNA specimens was used for 534 consecutive nodules in 534 patients. The FNA specimens were visually graded immediately following aspiration for each nodule, and the visual grades were classified into 2 categories: inadequate (<6 cell groups) and adequate (>6 cell groups). The cytology results were classified as diagnostic or nondiagnostic based on the Bethesda system. We compared the ultrasound features and FNA characteristics between the diagnostic and nondiagnostic results. Multiple logistic regression analysis was used to determine factors independently predictive of nondiagnostic results. We also evaluated the interobserver agreement regarding the visual assessment. Visual assessment was feasible in all patients, and the nondiagnostic rate was 11.6% (62 of 534). Nondiagnostic results were more frequent in the inadequate visual assessment group (38.1%) than in the adequate visual assessment group (10.5%) (P = .001). Independent predictive factors for nondiagnostic results were inadequate visual assessment (odds ratio, 5.18), >50% vascularity (odds ratio, 3.98), and macrocalcification (odds ratio, 3.60). Interobserver agreement for the prediction of visual assessment was good (κ value, 0.767; P<.001). Immediate visual assessment of a specimen during FNA of a thyroid nodule is a feasible method for predicting sampling adequacy.