Ultrasound guidance improves the adequacy of our preoperative thyroid cytology but not its accuracy

AIMS: Our thyroid cytology audit results of 1990-1995 showed an unsatisfactory rate of 43.1% and prediction of neoplasia with a sensitivity of 86.8%. Increasingly, ultrasound scan (USS)-guided core sampling for cytology is proving a valuable tool instead of freehand fine needle aspiration (FNA) or following unsatisfactory freehand FNA. We present the results of freehand FNA and USS-guided core samples for cytology in two separate patient groups in our centre. METHODS: Patients who had a thyroid resection and preoperative thyroid cytology in our institution between 1996 and 2002 were included. The histological diagnoses were correlated with the preceding cytology results. RESULTS: A total of 450 FNAs were performed on 394 patients. Freehand FNAs were performed for 348 (77.3%) samples and USS-guided core for 102 (22.7%) samples; 121 (26.8%) were repeat aspirates performed on 45 patients. Using aspiration cytology (AC) grading, freehand FNA was cytologically inadequate (AC0 or AC1) in 34.8% cases whereas USS-guided core was inadequate in 17.6% cases (P = 0.001). Freehand FNA (AC3, AC4, AC5) predicted neoplasia with a sensitivity of 83.2%, specificity of 46.6%, accuracy of 63.0%, positive predictive value of 56.0% and negative predictive value of 77.1%. USS-guided core sample for cytology (AC3, AC4, AC5) predicted neoplasia with a sensitivity of 93.5%, specificity of 26.0%, accuracy of 51.9%, positive predictive value of 43.9% and negative predictive value of 86.7%. CONCLUSIONS: Although USS-guided core provides more satisfactory specimens than freehand FNA, in our centre it does not provide increased accuracy.