This simple test uses sound waves to image the thyroid. The sound waves are emitted from a small hand-held transducer which is passed over the thyroid. You will lie on your back with your neck hyperextended (with a pillow under your shoulders) as best as you can. A lubricant jelly is placed on the skin so that the sound waves transmit easier through the skin and into the thyroid and surrounding structures. This test is quick, accurate, painless, inexpensive, and completely safe. It usually takes about 10 minutes and the results can be known almost immediately. The only preparation needed for an ultrasound is to wear a low or open collar shirt (try to avoid turtlenecks) and remove any jewelry from your neck.
There are certain characteristics of thyroid nodules seen on ultrasound which are more worrisome than others. Keep in mind, however, that ultrasound alone cannot make the diagnosis of cancer! This test will usually help tell us that the nodule has a low chance of being cancer (has characteristics of a benign nodule), or that it has some characteristics of a cancerous nodule and therefore a biopsy is indicated.
Ultrasound Characteristics Which Suggest a Benign Nodule
- Sharp edges seen all around the nodule
- Nodule filled with fluid and not solid tissue (a cyst)
- Lots of nodules throughout the thyroid
- No blood flowing through it
Ultrasound Characteristics – Higher Risk of Cancerous Nodule
- Irregular borders
- Microcalcifications (tiny specks of calcium)
- Increase blood flow inside the nodule
- Enlarged lymph nodes
Neck ultrasound can also be used to look at structures next to the thyroid gland, including lymph nodes and parathyroid glands.