The influence of fine-needle aspiration biopsy of the thyroid gland on the size of the examined nodule and its ultrasound image

INTRODUCTION The aim of the study was to assess the influence of thyroid fine-needle aspiration biopsy (FNAB) on the size and ultrasound (US) features of the lesions and to examine whether the possible effects are persistent. MATERIAL AND METHODS One hundred and fifty biopsied and 50 control thyroid nodules underwent two US examinations, 10-20 days and 8-10 weeks after the biopsy. The study took into account lesion volume alterations, both absolute and relative (with reference to its initial value), and the presence of US features of malignancy: hypoechogenicity, microcalcifications, internal blood flow, irregular or blurred margins and suspicious shape of the lesions. The analysis covered only those nodules which immediately after FNAB did not change their appearance owing to cyst fluid evacuation or intranodular hemorrhage. RESULTS The increase of the lesion volume was more frequent in the group of biopsied lesions than the control one (58.0% vs. 24.0%, p < 0.0001) with the highest increase of 61.5%. The mean change percentage, however, was determined below 5% and a tendency of the lesions to resume their initial volume was noticeable. Neither a persistent increase in nodule volume of above 50% nor significant changes in the presence of malignancy suggestive US features were observed after FNAB. None of the biopsied nodules developed any microcalcifications, irregular or blurred margins, internal blood flow, or suspicious shape. CONCLUSIONS Fine-needle aspiration biopsy does not cause permanent changes in the US image of biopsied lesions, provided that the sampling technique is appropriate and there are no significant changes observed during the biopsy.