Diagnostic accuracy of fine needle aspiration of the thyroid: a comparative study of the technique with and without ultrasonography

Abstract

Background and aim of the work: Fine needle aspiration biopsy (FNAB) of thyroid is an indispensable procedure in the evaluation of patients with thyroid nodules. The aim of this study was to evaluate the benefit of ultrasonography (USG)-guided FNAB compared to the conventional method. Methods: In this comparative cross-sectional study FNAB samples were collected in 1984 (G1) and 2011 (G2). In G1 (113 patients) FNAB was performed by palpation, and in G2 (1,049 patients) it was USG-guided. Statistical analysis included sensitivity, specificity, positive/negative predictive value, and likelihood ratio. Associations were considered statistically significant when p-value≤0.05. Results: The percentage of unsatisfactory material was 24% in G1 and 7.8% in G2. The sensitivity/specificity in G1 were 40% / 71%, and in G2, 83% / 94.7%. In G2, it was possible to select 77.7% of malignant nodules for surgery, while in G1 only 10%. In G2, the frequency of malignancies was similar between nodules smaller and larger than 1cm (Fisher’s exact test p-value=0.33). Conclusions: Our data confirm that FNAB is a valid technique for screening malignant thyroid nodules, especially when guided by USG. Since subcentimetric nodules harbor malignancy as much as larger nodules, we recommend performing FNAB in all thyroid nodules, regardless of size.