A thyroid ultrasound is a scan that uses sound waves to make pictures of the thyroid, a small gland at the front of your neck. It helps clinicians check the gland’s size and shape and look at lumps, called nodules. The test is usually painless, uses no radiation, and needs little preparation. You lie back while a technician moves a small probe over gel on your neck.
What Does a Thyroid Ultrasound Examine?
The thyroid is a butterfly-shaped gland at the lower front of your neck, just above your collarbones. It produces hormones that help regulate how your body uses energy and supports several important functions, including heart rate and body temperature.
A thyroid ultrasound, also called thyroid sonography, creates real-time pictures of the gland and nearby tissues. The examination uses a handheld device called a transducer, which sends high-frequency sound waves into the body and receives the returning echoes. A computer converts these echoes into images that a healthcare professional can examine.
Unlike an X-ray or CT scan, a standard thyroid ultrasound does not use ionizing radiation. It is a noninvasive imaging test, meaning that the scan itself does not require needles, injections, or cuts. According to RadiologyInfo, a patient resource reviewed by the American College of Radiology and the Radiological Society of North America, ultrasound is commonly used to assess thyroid lumps and examine changes in the gland over time.
Why Would a Doctor Order a Thyroid Ultrasound?
Your healthcare professional may recommend this scan after finding a lump or swelling in your neck, noticing an enlargement during a physical examination, or seeing a possible thyroid abnormality on another imaging test. It can also help evaluate certain symptoms, such as a sensation of pressure in the neck or difficulty swallowing, when further examination of the thyroid is appropriate.
Another common reason is to monitor a thyroid nodule that has already been identified. Comparing images from different appointments helps clinicians assess whether a nodule has changed in size or appearance. The scan can also show whether additional nodules are present and examine nearby lymph nodes when needed.
A thyroid ultrasound is often part of a wider evaluation rather than a complete answer on its own. Your medical history, physical examination, symptoms, blood test results, and previous imaging findings help your clinician decide why the scan is needed and whether any follow-up is appropriate.
How Should You Prepare for a Thyroid Ultrasound?
Most people do not need special preparation. For a routine thyroid ultrasound, fasting is usually unnecessary, and you can generally eat, drink, and take your usual medicines as normal. The Cleveland Clinic's patient guidance on thyroid ultrasound confirms that most people can maintain their usual routine before the examination.
A few simple steps can make the appointment more comfortable:
- Wear a comfortable top with a neckline that gives easy access to your neck.
- Remove necklaces and other jewelry around the area being examined.
- Bring any relevant previous thyroid ultrasound reports or imaging results if your clinician or imaging center requests them.
- Tell the imaging team if you have difficulty lying flat, neck pain, or another issue that may affect your position during the scan.
You usually do not need to stop any medication for a routine ultrasound. However, if a biopsy or another procedure is scheduled at the same visit, its preparation instructions may be different. Follow the instructions provided by your healthcare team.
What Happens During a Thyroid Ultrasound?
The examination is usually performed in a hospital imaging department, an outpatient center, or a healthcare professional's office. A sonographer, who is trained to perform ultrasound examinations, or another qualified healthcare professional will carry out the scan. The process is straightforward and typically involves the following steps.
1. You lie on the examination table
You will usually lie on your back with your head supported. The sonographer may ask you to tilt your head slightly backward to make the front of your neck easier to examine. You may be given a pillow or support beneath your shoulders. Depending on the facility and your clothing, you might be asked to change into a gown or move your collar away from the scanning area.
2. Gel is applied to your neck
The sonographer places a small amount of water-based gel on the skin over your thyroid. This gel helps the probe make good contact with your skin so that the sound waves can travel effectively into the tissues. It may feel cool at first, but it is easy to wipe off after the scan and generally does not stain clothing.
3. The sonographer moves the probe over your skin
A small handheld device called a transducer is moved gently across the gel. It sends sound waves into the neck and records the echoes that return. These are converted into pictures on a monitor, allowing the sonographer to examine the thyroid from different angles. Measurements and additional images may be taken of the gland, any nodules, and nearby structures.
MedlinePlus explains that the procedure involves positioning the neck, applying gel, and moving the transducer over the skin. During a standard thyroid ultrasound, the sonographer does not insert a needle or inject contrast material. You may be asked to remain still while the necessary images are captured.
4. The gel is removed and the examination ends
Once enough images have been collected, the sonographer wipes the gel from your neck. You can usually get dressed and return to your usual activities immediately. There is generally no recovery period, and a routine thyroid ultrasound does not usually require someone to accompany you home.
Does a Thyroid Ultrasound Hurt, and How Long Does It Take?
A thyroid ultrasound is generally painless. You may notice the cool gel or mild pressure as the probe moves over your neck. If the area is already tender, the pressure may be uncomfortable, so let the sonographer know if you need them to adjust their technique or your position. The sound waves themselves are not something you can feel or hear during the examination.
The scan often takes around 30 minutes, although the actual time depends on the number of images required and whether there are nodules or other areas that need closer examination. According to the Cleveland Clinic's overview of the procedure, the duration can vary according to what the healthcare professional needs to assess.
What Can a Thyroid Ultrasound Show?
The scan provides information about the thyroid's appearance, including its size, shape, and internal structure. It can identify enlargement of the gland, often called a goiter, and detect nodules that may be too small to feel during a physical examination. A nodule is a lump within the thyroid that may contain fluid, solid tissue, or a mixture of both.
Ultrasound images also help clinicians assess the size and appearance of nodules and look for features that may influence whether further testing is needed. Many thyroid nodules are benign, meaning they are not cancerous. Their discovery does not automatically mean that cancer is present or that treatment is necessary.
The American Thyroid Association explains that thyroid ultrasound helps characterize nodules, identify features associated with a higher risk of cancer, and guide decisions about whether a fine-needle biopsy may be needed. Clinicians consider the nodule's appearance and size when deciding whether to recommend monitoring, additional tests, or a biopsy.
Can a Thyroid Ultrasound Detect Thyroid Cancer?
A thyroid ultrasound can identify features of a nodule that are more concerning, but it cannot confirm cancer by itself. Some noncancerous nodules have appearances that require closer evaluation, while ultrasound findings alone may not establish the nature of every nodule.
Some reports include a thyroid nodule classification or risk score, such as TI-RADS. This system groups ultrasound features into categories to help clinicians decide whether monitoring or a biopsy is appropriate. A score is not a cancer diagnosis, and the recommended next step depends on the findings and clinical context.
If a nodule needs further evaluation, your clinician may recommend a fine-needle aspiration biopsy. This is a separate procedure in which a thin needle collects a small sample of cells from the nodule for examination in a laboratory. Ultrasound may be used to guide the needle to the correct location. Not everyone who has a thyroid ultrasound needs a biopsy.
Does a Thyroid Ultrasound Show Whether Your Thyroid Is Working Properly?
A thyroid ultrasound examines the gland's structure, not how much thyroid hormone it produces. A scan cannot determine by itself whether your thyroid is underactive or overactive. Those questions are usually assessed with blood tests, including thyroid-stimulating hormone (TSH) and, when indicated, thyroid hormone measurements such as free thyroxine (free T4).
RadiologyInfo notes that ultrasound cannot measure thyroid function, so your clinician may combine the scan with blood tests and other information when assessing a possible thyroid disorder. The two types of tests provide different information and may both be useful, depending on why the examination was requested.
What Happens After the Ultrasound?
After the scan, the images are reviewed and a report is prepared, usually by a radiologist or another appropriately qualified clinician. The report is sent to the healthcare professional who requested the examination, who can explain what the findings mean in relation to your symptoms, medical history, and previous test results.
A normal result may mean that no further imaging is needed at that time, depending on why the scan was ordered. If the report identifies a nodule or another change, the next step could be a repeat ultrasound to monitor it, blood tests to assess thyroid function, or a biopsy if the findings justify further investigation. An abnormal report does not automatically mean that you have a serious condition.
The time it takes to receive your results varies by facility and how the images are reviewed. Ask the imaging center or the clinician who ordered the scan when you should expect the report and how you will receive it. If you have a new or growing neck lump, persistent swallowing difficulty, or another concerning change, discuss it with a healthcare professional even if an earlier ultrasound was reassuring.
Is a Thyroid Ultrasound Safe?
A standard diagnostic thyroid ultrasound is considered very safe. It uses sound waves rather than ionizing radiation and has no known harmful effects when performed appropriately. The procedure is noninvasive, and most people experience little or no discomfort. There is usually no need to rest afterward or make changes to your normal activities.
Keep in mind that an ultrasound and an ultrasound-guided biopsy are different procedures. The routine scan uses a probe on the skin, while a biopsy involves a needle to collect a tissue sample. If your clinician recommends a biopsy after reviewing the ultrasound report, they should explain why it may help, what it involves, and what preparation is needed.
Overall, a thyroid ultrasound is a simple way to examine the gland and investigate findings such as a neck lump or thyroid nodule. Understanding what the scan can and cannot show can help you feel more prepared for the appointment and discuss any recommended follow-up with your healthcare professional.