Thyroid nodule fine-needle aspiration.

Thyroid nodules are a common clinical problem and are noted much more commonly on imaging examinations than are apparent by palpation. Fine-needle aspiration biopsy (FNA), which yields a cytology specimen for analysis, is the standard test to determine whether surgical removal of a detected nodule is recommended. This article will review the current guidelines for recommending FNA of thyroid nodules, the technique and risk of the procedure, and the implications for patient care based on FNA results. FNA has an essential role in the evaluation of patients with thyroid nodules to reduce the rate of unnecessary thyroid surgery for patients with benign nodules and triage patients with thyroid cancer to appropriate surgery. Before the routine use of FNA, approximately 14% of resected thyroid nodules were malignant, whereas with the current widespread use of thyroid nodule FNA, >50% of resected thyroid nodules are malignant. Historically, thyroid nodules were identified by physical examination of the neck, with a prevalence of approximately 5%-10% of adults in the United States, and these patients underwent palpation-guided FNA in the physician's office. In recent years, the increased use of sonography to examine the thyroid as well as cross-sectional imaging of the neck by computed tomography and magnetic resonance imaging has resulted in the detection of many nonpalpable nodules. In older adults, thyroid nodules may be detected in >67% of people screened by sonography. Fortunately, the vast majority of nodules are benign, but when they are discovered, an assessment regarding the need to exclude malignancy using FNA must be performed.