[Use of clinical ultrasound in primary care: Thyroid nodule].

The thyroid nodule is a frequent lesion within the thyroid. Its incidence is between 50%-60% and most of them are asymptomatic and benign (90-95%) and its diagnosis is frequently made as an incidental finding. The main objective of their study is to rule out thyroid cancer. Cervical ultrasound is the non-invasive diagnostic technique of choice to study the thyroid gland and its pathology, including the thyroid nodule, as it is the technique with the best cost-benefit ratio. Together with the anamnesis, physical examination, personal and family history and laboratory tests, it enables the first diagnostic approach. Ultrasonography allows the description of thyroid nodules according to their structure, morphology, margins, size,echogenicity, vascularization, calcifications and whether or not there are pathological lymph nodes. Subsequently, the application of risk stratification systems, such as the TI-RADS classification, will make it possible to identify those nodules suspected of having a high risk of malignancy, establishing the indication for FNA, which is decisive for the subsequent therapeutic approach. Ultrasound therefore allows the family physician a quick orientation of the patient with a thyroid nodule, especially useful when there is a high suspicion of malignancy. As it is an operator-dependent technique, acquiring knowledge and skills in its use will increase diagnostic reliability.