What Is a Thyroid Ultrasound?

What to expect when undergoing this test

A thyroid ultrasound is a safe, painless procedure that uses sound waves to examine the thyroid gland. It can be used to help diagnose a wide range of medical conditions affecting the thyroid gland, including benign thyroid nodules and possible thyroid cancers.

Afro child lying when doctor scanning her neck
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Purpose of Test

Clinicians can use thyroid ultrasound to evaluate several different medical conditions that affect the thyroid gland, an endocrine gland in your neck. The thyroid hormone produced by the gland affects many important physiological functions, including heart rate, body temperature, and overall metabolism.

Sometimes you might receive the scan as part of an overall medical exam, especially if you have symptoms that might be consistent with thyroid disease, like fatigue. Some people get a thyroid ultrasound because a small bump was noted in the region. You might get the test if other tests results are abnormal, like a thyroid function test.

Sometimes thyroid ultrasounds are used for screening. If you have an increased risk of getting thyroid cancer (for example, from certain kinds of genetic diseases), you might need regular thyroid ultrasounds. Or this might be the case if you’ve previously had radiation therapy applied to that part of your body.

Thyroid ultrasound can also be used to monitor the area for a recurrence of cancer if you’ve previously had a thyroid cancer removed.

Parathyroid Ultrasound

The parathyroid glands, which lie just next to the thyroid glands, release parathyroid hormone. This hormone is very important for regulating calcium in the body. A similar type of ultrasound can be used to evaluate the parathyroid glands, for example, in someone with a potential parathyroid adenoma or another possible parathyroid problem.

Other Imaging Methods

Ultrasound has largely replaced a previous mode of imaging the thyroid called thyroid scintigraphy. This is a type of medical imaging that requires taking radioactive iodine. This technique is sometimes still used for people who have hyperthyroidism or for monitoring after removal of a thyroid cancer.

Unlike scintigraphy imaging, the thyroid ultrasound doesn’t require exposure to radiation, which can potentially increase one’s future risk of cancer.

Other imaging tests are used to look at the thyroid gland, but not as commonly as ultrasound. They are most often used when the diagnosis is still unclear after an ultrasound (and potentially other medical tests) have already been performed.

Such tests include medical resonance imaging (MRI), computerized tomography (CT), and positron emission tomography (PET) scans. These tests are all more expensive than ultrasound. Unlike ultrasound, CT and PET scans do require radiation exposure as well.

How Thyroid Ultrasound Works

Ultrasound imaging (also called sonography) uses high-frequency sound waves to produce images of the inside of the body. The sound waves reflect off the internal body structures, but at different strengths and speeds, depending on the nature of those structures. This information is compiled by a computer to produce the ultrasound images, which appear on a screen.

Ultrasound produces moving images in real-time, so clinicians can see features like the movement of organs and blood flow through vessels. Many people are most familiar with ultrasound from its use during pregnancy. But ultrasound imaging has become more frequent in many other areas of medicine as well, including in the diagnosis of thyroid disease.

Risks and Contraindications

Thyroid ultrasounds are very safe and cause no known complications. The sound waves used to create the ultrasound image cause no known side effects. In fact, one of the advantages of ultrasound over some other imaging techniques is its safety record.

Thyroid Nodules

One concern about the increasing use of ultrasound is the greater number of thyroid nodules being detected. Ultrasound will identify very small nodules that you would be unable to physically feel as a lump in the throat area.

Most of these nodules are harmless, and extra investigation and treatment may be unnecessary. Even when these nodules are truly cancerous, they are often small and low-risk cancer types, and the risks of interventions might outweigh the benefits in some cases.

Clinicians are still learning about how to make sure this test is given to the people who really need it and is interpreted in exactly the right way. That will make it less likely that a harmless nodule detected on ultrasound would lead to unnecessary treatments.

Before the Test

Thyroid ultrasound takes place after a medical evaluation, including a medical history and a clinical exam. Your clinician will first need to make sure that that the technique will be potentially helpful in your specific situation.

Timing

Typically, the painless procedure only takes a few minutes. You won't be anesthetized, so you can drive home or return to work immediately after the procedure.

Location

A thyroid ultrasound might be done in a hospital setting, clinic, or right in a medical office. You should bring your paperwork and health insurance card.

Preparation

Thyroid ultrasound does not require any preparation on the part of the patient. You can take your medications and eat and drink normally ahead of time.

What to Wear

If your clothing does not obscure your neck, you won't need to remove your shirt. If necessary, you can change into a gown. You’ll need to remove anything that might block access to your neck, like a necklace.

During the Test

Depending on the context, your thyroid ultrasound might be administered by a radiologist or by another clinician, like an endocrinologist with expertise in thyroid care. Or, it may be performed by a sonographer, a health professional trained in diagnostic ultrasound.

Thyroid ultrasound may be performed with the person reclining, but it can also be done while seated. The chin is tilted back to allow the front of the neck to be extended.

Just before the test, a thin layer of gel is applied to the skin on the front of the throat. This may feel a little cold at first.

In some cases, your doctor will recommend the use of a contrast agent to help get better images. This involves injecting a material such as Lumason into a blood vessel before the procedure. However, this is not always done. You can ask your healthcare provider about whether to expect this.

The clinician takes a handheld device called a transducer (or probe) and places it directly on the skin on the front of your throat. The clinician may move the transducer around a bit, to get a thorough view of the thyroid gland. You might be asked to swallow or bear down to help get a better image.

During the test, the clinician will examine the area thoroughly and see if anything looks unusual, taking into account the overall size and shape. If there is a bump on the thyroid gland, they can measure its size and location and can even get some information about its blood supply.

The ultrasound can show if such an area is solid or filled with fluid. Ultrasound can also help your doctor get an idea of whether such an area is likely to be benign and harmless or a potential cancer.

Once the ultrasound is complete, the gel can be wiped away from the area.

Simultaneous Tests

Sometimes, thyroid ultrasound is combined with thyroid biopsy (also called fine-needle aspiration or FNA). This may be needed if your doctor is concerned that a thyroid nodule might be cancerous, due to the way it appears on ultrasound.

For example, if the area is irregular and it is invading the surrounding tissue, there’s a greater risk that it is cancer. However, as thyroid nodules are only rarely cancerous, this is usually not needed. A biopsy might also be needed for a particularly large nodule.

Thyroid ultrasound is sometimes combined with thyroid therapies as well. For example, certain types of thyroid nodules can be treated via an injection of ethanol into the nodule (called ethanol sclerotherapy). This provides a less invasive intervention compared to surgical removal. Ultrasound imaging ensures that the doctor injects the ethanol in exactly the right spot.

After the Test

There is no recovery time needed after a thyroid ultrasound test. You’ll be able to go about your business as usual.

If your test is being performed by the physician managing your treatment, you can talk right then about how the test information will impact your future care. In other cases, you’ll need to follow-up in a few days, after a radiologist or other professional has examined the images.

No follow-up may be needed. But further tests or procedures might be necessary, depending on the context.

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Interpreting Results

One of the limits of the thyroid ultrasound is that it doesn’t tell you whether your thyroid might be producing too much or too little thyroid hormone. In other words, it won’t tell you if you have hyperthyroidism or hypothyroidism. That requires other tests, for example, a blood test for different types of thyroid hormone or for thyroid stimulating hormone (TSH).

For diagnosis, the results of a thyroid ultrasound must be considered along with other clinical information and other tests. Some medical conditions involving the thyroid may have a very similar appearance on a thyroid ultrasound, such as Hashimoto’s thyroiditis and Graves’ disease. However, other clinical symptoms and tests can help distinguish the two.

Sometimes, ultrasound alone cannot determine whether a nodule is cancerous. If so, you may need to get a biopsy of the node that can be examined under a microscope. This is often done in conjunction with another thyroid ultrasound. If you do have thyroid cancer, your doctor may recommend surgery or another treatment strategy.

A Word From Verywell

Examination of the thyroid via ultrasound is a painless and fairly quick process. If you are concerned about a potential thyroid issue, it may be worth talking with your physician to see if a thyroid ultrasound might provide some helpful information. 

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