Fine-needle aspiration of the thyroid has a higher sensitivity when performed under ultrasound guidance [12–15]. However, because an ultrasound system is not available in every office, palpable thyroid nodules can still be biopsied without ultrasound guidance if absolutely necessary.

During this procedure, the patient is lying down with cervical hyperextension, using a pillow placed behind the patient’s shoulders (Fig. 4.3), while the clinician holds the thyroid nodule between his or her fingers (Fig. 4.4). The person performing the fine-needle aspiration will be standing on the opposite side of the lesion, so the needle is introduced from the neck midline in an effort to avoid going through large muscles and blood vessels. The patient is asked not to swallow or speak during the procedure to preclude movement of the thyroid. As mentioned above, one of the disadvantages of this technique is the imprecise needle placement due to lack of direct nodule visualization during the procedure.

There are two main methods of aspiration of thyroid nodules under US guidance: transverse and longitudinal approaches.

With the transverse approach, the US probe is placed anterior to the nodule in question which should be positioned in the middle of the screen. A small button of local anesthetic (usually lidocaine without epinephrine) is injected in the subcutaneous area. The use of local anesthesia is optional, since the pain of injection is at times more uncomfortable than the fine needle puncture itself. The ultrasonographer would then introduce the fine needle exactly in next to the middle of the probe transversely, which should coincide with the middle of the screen where the nodule is located (Fig. 4.5). With this technique, the entire length of the needle cannot be visualized. The ultrasonographer should look for the subtle appearance of the needle on the screen at the time it enters the lesion in question. At this point, the needle is moved in and out with short and quick movements, back and forth inside of the nodule which can be done while aspirating the nodule or not. When the sample is collected, the aspiration should be released and the needle should be removed smoothly. This movement is the key for FNA of the thyroid and this repetitive motion should occur for approximately 10 seconds during each pass. The fine needle will collect the tissue in the bore by capillary action even if no active aspiration is applied, which is an important technique to decrease the blood in the aspirate, especially in hypervascular lesion biopsies. For most thyroid FNA guided by US, an adequate specimen is obtained with three passes. The advantage of the transverse technique is that it requires slightly less precision in the placement of the needle when compared to the longitudinal method; however, it can also be less accurate because the exact location of the tip of the needle is unknown unless the ultrasonographer can identify the needle tip appearing and disappearing from the screen while inside of the thyroid lesion with these short movements in and out of the imaged nodule.