Role of Ultrasound-Guided FNAC in the Evaluation of Thyroid Nodules: A Prospective Study

Background: Thyroid nodules are common endocrine lesions, and distinguishing benign from malignant nodules is essential for appropriate management. Ultrasound-guided fine-needle aspiration cytology (USG-guided FNAC) improves sampling accuracy and is considered the investigation of choice for evaluating thyroid nodules. The objective is to evaluate the diagnostic role of ultrasound-guided FNAC in thyroid nodules and assess its cytological adequacy, diagnostic accuracy, and cyto-histopathological correlation. Material and Methods: This prospective observational study included 110 patients with thyroid nodules who underwent ultrasound-guided FNAC. Nodules were assessed using high-resolution ultrasonography, and cytological findings were reported according to the Bethesda System for Reporting Thyroid Cytopathology. Histopathological correlation was performed in surgically managed cases. Diagnostic indices including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall diagnostic accuracy were calculated. Results: Females constituted 78.2% of the study population, and solitary thyroid nodules were observed in 58.2% of patients. Bethesda Category II (Benign) was the most frequent cytological diagnosis (60%), while only 3.6% of aspirates were non-diagnostic. Histopathological correlation showed 94.1% concordance between cytology and histopathology. Ultrasound-guided FNAC demonstrated a sensitivity of 93.3%, specificity of 97.1%, positive predictive value of 93.3%, negative predictive value of 97.1%, and an overall diagnostic accuracy of 95.6%. Suspicious ultrasonographic features including microcalcifications, irregular margins, hypoechogenicity, and increased intranodular vascularity were significantly associated with malignant cytological diagnoses (p<0.05). Conclusion: Ultrasound-guided FNAC is a highly accurate, safe, and minimally invasive technique for evaluating thyroid nodules. Its excellent diagnostic performance, low inadequacy rate, and strong cyto-histopathological correlation make it an indispensable tool for the early diagnosis and appropriate management of thyroid malignancies.

Keywords: Thyroid nodules, ultrasound-guided FNAC, thyroid cytology, Bethesda System, ultrasonography, thyroid cancer, histopathology.