Thyroid Ultrasound

What it is

The thyroid sits just under the skin at the base of the neck, which makes it close to ideal for ultrasound: a high-frequency probe held against the throat resolves it in fine detail without radiation and without any injection. The scan reports the size of each lobe and then, for any nodule found, a set of descriptive features — whether it is solid or fluid-filled, its edges, its internal texture, whether it contains tiny calcium specks, and how blood flows through it. Those features, taken together, sort nodules into categories of concern. That sorting is the real product of the study. Ultrasound cannot tell whether a nodule is cancerous; it tells a doctor which nodules are worth sampling with a needle and which can be left alone or simply re-measured later. Nor does it say anything about thyroid function — that is a blood test.

Why it is done

• To evaluate a lump felt in the neck, and to establish whether it arises from the thyroid at all
• To characterize a nodule discovered incidentally on a CT, MRI or other scan done for another reason
• To measure an enlarged thyroid, or a gland that is pressing on surrounding structures
• To decide which nodules should have a fine-needle biopsy
• To re-measure known nodules over time and see whether any has grown
• To check lymph nodes in the neck in someone with a known thyroid problem

What to expect

No preparation is needed — no fasting, no injection, no change of clothing beyond removing necklaces. The patient lies on their back with a pillow or cushion under the shoulders so the neck extends and the gland comes forward. Warm gel is applied and the sonographer moves a small probe across the throat, sometimes asking for a swallow or for the head to be turned. Mild pressure on the windpipe can feel odd but is not painful, and the scan typically takes 15 to 30 minutes. If a biopsy is planned it is generally a separate appointment. A radiologist reviews the images and reports afterward.

Questions worth asking

• If a nodule is found and a needle biopsy is recommended, ask what that visit costs as a whole: the biopsy procedure, the ultrasound guidance for it, and the pathologist's reading are typically three separate charges.
• Will repeat surveillance scans be recommended, and at what interval? A yearly scan means a fresh charge against a fresh deductible each time.
• Is this being done in an endocrinology or surgical office, or in hospital radiology, and does a facility fee apply in one and not the other?
• Is the reading physician's fee billed separately from the scan, and is that physician in network?