Updated 22 September 2015

Thyroid ultrasound

Ultrasound is high-frequency sound that is generated electronically by a machine and special crystals in a probe.


Alternative names

Thyroid sonar or thyroid scan

What is a thyroid ultrasound?

Ultrasound is high-frequency sound that is generated electronically by a machine and special crystals in a probe. The sound travels through your body, and bounces off different tissues and back to a receiver on the same probe. These sound waves are interpreted into a digital image in real time.

The thyroid ultrasound examines your thyroid, the gland situated in the neck just below the Adams apple, with two lobes on either side of the midline connected in the midline by a narrow band of tissue. It is one of the nine endocrine glands in the body that makes and sends hormones into the bloodstream to regulate certain body functions.

What are the common uses of the procedure?

The thyroid ultrasound is performed to help diagnose enlarged thyroid lobes or irregularity or lumps in the thyroid, including benign or malignant (cancerous) growths. It also helps evaluate a malfunction of the thyroid gland. Furthermore it can be used to guide procedures such as needle biopsies to obtain sample cells from an abnormal area for laboratory testing.

How should I prepare?

Wear comfortable, loose-fitting clothing. You may need to remove all jewellery in the area to be examined, and be asked to wear a gown.

No other preparation is required.

How is the procedure performed?

You will lie on your back on the examination table. A small pillow may be placed under your shoulder, and the neck slightly extended to gain access and better visual of the thyroid gland. A clear gel is applied to the skin in the region of the thyroid and the radiologist then presses the transducer firmly against the skin over the area to be examined until the desired images are obtained. The examination is usually painless, fast and easy. Occasionally it is slightly uncomfortable as the radiologist or sonographer passes over an area of tenderness, but this is most often transient. The radiologist may stop occasionally to take measurements or other assessments of lesions seen in the thyroid gland.

The ultrasound examination is usually completed within 30 minutes and the gel will be wiped off your skin.

You may be asked to wait while the radiologist or sonographer analyses the images and a written report is given to you for your referring doctor.

The radiologist may discuss preliminary results with you at the end of your exam if

you so request.

What are the risks?

This procedure is non-invasive (no needles or injections). It is easy to use and less expensive than other imaging methods. It uses no ionizing radiation and provides clear pictures of soft tissues that do not show up well on X-ray images; in addition the ultrasound provides real-time imaging, thus making it a good tool to guide minimally invasive procedures such as needle biopsies, also known as a fine needle aspiration biopsy or FNAB.

There are no known harmful effects for the standard diagnostic ultrasound examination, and is safe to perform during pregnancy.

What are the limitations?

Some lesions or lumps may be visible on the sonar exam, but the exact nature or pathology may not be clear and may need further evaluation by FNAB, and examination of the tissue under the microscope in the laboratory. In some cases a repeat or follow up sonogram after a few months, to look for stability of the lesion may suffice.


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