Cytological Accuracy of Nonguided Fine Needle Aspiration from the Thyroid - A Two-Year Experience from Southern India

Abstract

Introduction: 12.2% of the Indian have a palpable thyroid nodule, but only 5% of these are malignant. The rest of the patients do not need to undergo surgery, unless clinically indicated for other reasons. Fine needle aspiration cytology (FNA) from the thyroid gland is the most commonly performed screening investigation to determine whether a patient needs surgery or not. The sensitivity, specificity and accuracy of FNA should therefore, be audited in every Institute from their own data. Materials and Methods: A retrospective analysis of the case records of all patients of thyroid nodules who underwent surgery at our hospital between September 2019 and September 2021 was undertaken. Clinical, demographic details as well as correlation between the nonguided FNA report and the final histopathology was done. The sensitivity, specificity, positive and negative predictive value as well as accuracy of FNA was calculated. Results: The sensitivity of FNA for malignancy was 73.1% and the specificity was 89.3%. The positive predictive value was 85.7% and the negative predictive value was 79.2%. The accuracy of nonguided FNA was 81.8%. Conclusions: Though there were no inadequate smears, the high false negative rate and the lower accuracy point toward the need to use ultra-sonography guidance in selected cases to overcome the pitfalls of nonguided FNAs.