A palpable thyroid nodule is a common clinical problem; the ultrasonography (US) and fine
needle aspiration biopsy (FNA) are its main diagnostic tools. This article aimed to study the
reliability and advantages of ultrasound as a diagnostic aid in predicting malignancy in thyroid
nodules and to reduce the number of unnecessary surgery. Two hundreds and thirty three
patients were examined by ultrasound, and then fine needle aspiration cytology under
ultrasound guidance (US-FNAC) was done for 210 of them. From those 210 patients we
obtained the histopathological proof of 58 patients who underwent surgery. We calculated the
sensitivity, specificity and accuracy of US-FNAC. There are certain sonographic criteria that
suggest malignancy these include microcalcification, irregular margins, and hypoechogenicity of
the nodule. The sensitivity, specificity, and accuracy of US-FNAC were 80%, 96%, and 94%
respectively. Although ultrasound can not reliably distinguish benign from malignant nodules,
but it can identify suspected nodules based on certain sono-graphic criteria.