Diagnostic accuracy of ultrasound-guided fine needle aspiration cytology of thyroid nodules at Universitas Academic Hospital, Bloemfontein

Abstract

Background: Fine Needle Aspiration Cytology (FNAC), is safe, reliable and minimally invasive first-line investigation used to evaluate thyroid nodules. Aim: To determine the diagnostic accuracy of FNAC performed at our institution by correlating its results with histopathological diagnoses. Methods: A retrospective analysis was conducted of cytology and histopathology results of patients who underwent both FNAC and thyroidectomy at Universitas Hospital, Bloemfontein, over a 5-year period (2014–2018). Cytological findings were classified into six Bethesda categories while histological results were categorised as benign or malignant. Adult patients (≥ 18 years) who underwent both thyroidectomy and FNAC for nodular thyroid disease were included. Results: Sixty-one cases fulfilled the inclusion criteria. On cytological examination, 28/61 (45.9%) were reported as benign, 11/61(18.0%) as malignant and 10/61(16.4%) as suspicious. On histopathological reports, 29 cases were confirmed as benign and 10 as malignant. Among 10 suspicious cases, four were malignant on histopathology. False positive and false negative rates were 15.3% and 12.8%, respectively. The sensitivity and specificity were 50.0% and 79.3%, respectively. The positive and negative predictive values were 45.5% and 82.1%, respectively. The diagnostic accuracy of FNAC was 71.8%. Conclusions: FNAC at our institution has not performed as good as most similar studies published previously.