Zeitschrift für Schilddrüsenerkrankungen und -therapie
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Ultrasound Guidance Improves The Diagnostic Yield And Accuracy Of Fine Needle Aspiration Biopsy Of Thyroid Nodules In Detecting Malignancy

Celeste Ong-Ramos

Objective To compare the diagnostic accuracy of ultrasound guided fine needle aspiration biopsy (USG-FNAB) versus palpation guided thyroid biopsy. 1.2 Study Design Cross sectional study of patients who underwent thyroidectomy at our institution from May 2012 to June 2013 were included. Final Histopathology was compared with their cytology result whether it was obtained thru ultrasound guided or palpation guided FNAB. Sensitivity, specificity, positive and negative predictive value, accuracy rate and non-diagnostic yield were computed. 1.3 Subjects A total of 207 patients underwent thyroidectomy from May 2012 to June 2013. Seventy eight patients were excluded because of unavailability of cytology result (n=64) and had prior thyroidectomy (n=14). Only 129 patients were included in the study. Each site of the thyroid nodule that underwent FNAB was considered as one case. 1.4 Outcome Ultrasound Guided FNAB group (n=118) has a sensitivity of 78.57%, specificity 91.67%, positive predictive value 86.84%, negative predictive value 85.94%, accuracy rate of 86.2%. Palpation Guided FNAB group (n=57) has a sensitivity of 30.7%, specificity 100%, positive predictive value 100%, negative predictive value 81.25%, accuracy rate of 82.69%. Nondiagnostic yield for USG FNAB is 4% and Palpation FNAB is 12%. 1.5 Conclusion Ultrasound guidance improves sensitivity and overall diagnostic accuracy of FNAB in detecting thyroid malignancy. More importantly, it significantly lessens the non-diagnostic yield by 3x. Furthermore, USG FNAB was able to detect 6 out of 11 cases of micropapillary thyroid cancer translating it into 54.5% sensitivity in detecting micropapillary carcinoma. The improved diagnostic yield and accuracy rate of USG FNAB justify the additional cost of the procedure.