Ultrasound is a painless method that uses sound waves to create images of the inside of the body. The test is usually done in the ultrasound or radiology department. It also can be done in a clinic.
The test is done in the following way:
You lie with your neck on a pillow or other soft support. Your neck is extended beyond its usual limit (hyperextended).
The ultrasound technician applies a water-based gel on your neck to help with the transmission of the sound waves.
Next, the technician moves a wand, called a transducer, back and forth over the area. The transducer gives off sound waves. The sound waves go through the body and bounce off the area being studied (in this case, the thyroid gland). A computer looks at the pattern that the sound waves create when bouncing back, and creates an image.
How to Prepare for the Test
No special preparation is necessary for this test.
How the Test will Feel
You should feel very little discomfort with this test. The gel may be cold.
Why the Test is Performed
A thyroid ultrasound is usually done when you have a growth on your thyroid gland or when a routine exam finds that the thyroid feels big. The exam can help tell the difference between a nodule containing fluid (cyst), and a nodule that is solid and may contain abnormal tissue that may or may not be cancerous (a tumor). Sometimes the thyroid is enlarged without any nodules.
The thyroid is of normal size, shape, and position.
Salvatore D, Davies TF, Schlumberger MJ, et al. Thyroid physiology and diagnostic evaluation of patients with thyroid disorders. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 11.
Solbiati L, Charboneau JW, Reading CC, et al. The thyroid gland. In: Rumack CM, Wilson SR, Charboneau JW, Levine D. Diagnostic Ultrasound. 4th ed. Philadelphia, PA: Elsevier Mosby; 2010:chap 18.
Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.