Thyroid Ultrasound: Purpose, Procedure, Results, and What to Expect

At Independent Physicians Medical Center (IPMC) in Northeast Philadelphia, we offer thyroid ultrasound imaging performed by experienced sonographers and interpreted by board-certified radiologists in a private, comfortable outpatient setting.

What Is a Thyroid Ultrasound?

A thyroid ultrasound is a painless, noninvasive imaging test that uses high-frequency sound waves to create detailed pictures of your thyroid gland and surrounding structures, including nearby lymph nodes. A small transducer is placed against the skin of your neck and sends sound waves into the tissue. When those waves bounce back, a computer converts them into real-time images displayed on a screen.

Because ultrasound does not use any radiation, it is extremely safe and can be repeated as often as needed. It provides high-resolution images that allow your doctor to examine the size, shape, and internal structure of your thyroid — as well as any growths within or near the gland.

Why Would Your Doctor Order a Thyroid Ultrasound?

There are many reasons your doctor may recommend a thyroid ultrasound:

• Abnormal thyroid function test results. If blood tests show your thyroid is overactive (hyperthyroidism) or underactive (hypothyroidism), an ultrasound helps your doctor see the structural condition of the gland
• A lump or nodule felt during a physical exam. If your doctor feels a growth while examining your neck, ultrasound determines the size, location, and characteristics of the nodule
• Swelling or enlargement of the thyroid (goiter). Ultrasound measures the gland and looks for underlying causes of the swelling
• Difficulty swallowing or a sensation of fullness in the throat. These symptoms can be related to thyroid enlargement or nodules pressing on nearby structures
• Family history of thyroid cancer or thyroid disease. Your doctor may recommend periodic ultrasound screening for early detection
• Monitoring previously identified thyroid nodules. Regular ultrasounds track changes in size or appearance over time
• Guiding a fine needle aspiration (FNA) biopsy. When a nodule needs to be tested for cancer, ultrasound guides the needle precisely into the nodule to collect a tissue sample
• As part of a comprehensive physical exam. Some doctors include thyroid ultrasound as a routine screening tool, especially for patients with risk factors
• Post-surgical surveillance. After thyroid cancer surgery, ultrasound monitors the thyroid bed and cervical lymph nodes for any signs of recurrence

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How to Prepare for a Thyroid Ultrasound

One of the best things about a thyroid ultrasound is that virtually no preparation is needed. You can eat and drink normally, and there’s no need to stop any medications.

Remove necklaces and scarves or accessories that cover your neck area. Wear a comfortable top with a low or open neckline that allows easy access to your throat — you may be asked to remove your shirt or change into a gown. Bring your insurance card and a list of current medications.

In rare cases, your doctor may request a contrast-enhanced ultrasound, which involves injecting a small amount of contrast agent through an IV to improve image quality. This is uncommon for thyroid ultrasounds, and your doctor will let you know in advance if it’s needed.

What Happens During a Thyroid Ultrasound?

1. Positioning. You’ll lie on your back on a comfortable exam table with a pillow or pad placed under the back of your neck. This tilts your head slightly backward and exposes the front of your throat. While this position can feel a bit awkward, it is not painful. In some cases, you may be able to sit upright.
2. Applying the gel. The sonographer applies a clear, water-based gel to the skin of your neck over the thyroid area. The gel helps the transducer make solid contact and transmit sound waves effectively. It may feel slightly cool but warms quickly.
3. Scanning. The sonographer gently presses the transducer against your neck and moves it back and forth across the thyroid area. Images appear on a nearby screen in real time. The sonographer captures images of both lobes of the thyroid, the isthmus (the bridge connecting the lobes), and any nodules present. The surrounding lymph nodes in the neck are also examined.
4. Measurements. The sonographer measures the overall dimensions of the thyroid gland and the size of any nodules. If Doppler imaging is used, blood flow within the gland and any nodules is assessed.
5. Duration. A thyroid ultrasound typically takes 20 to 30 minutes.
6. Comfort. The test is painless — you may feel light pressure from the transducer. If any part of the exam causes discomfort, let your sonographer know.

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What Can a Thyroid Ultrasound Detect?

A thyroid ultrasound provides your doctor with a wealth of valuable information:

Solid vs. fluid-filled nodules. The ultrasound shows whether a growth is solid (which may require further evaluation), fluid-filled or cystic (almost always benign), or mixed (partially solid and partially cystic).

Number and location of nodules. It’s common for the thyroid to contain multiple nodules. The ultrasound maps each one.

Nodule characteristics. The radiologist evaluates features that help estimate the risk of cancer, including shape (taller-than-wide nodules are more concerning), margins (irregular or ill-defined borders raise concern), echogenicity (very dark/hypoechoic nodules relative to surrounding tissue carry higher risk), calcifications (microcalcifications — tiny calcium deposits — are associated with thyroid cancer, though they don’t always indicate it), and composition (completely solid nodules are evaluated more carefully than cystic ones).

Blood flow patterns. Doppler ultrasound measures blood flow within nodules and the gland. Certain flow patterns can suggest increased metabolic activity.

TI-RADS scoring. Radiologists often use a standardized system called TI-RADS (Thyroid Imaging Reporting and Data System) to categorize nodules. Each nodule receives a score from TR1 (benign) to TR5 (highly suspicious), with recommendations for whether a biopsy is needed based on the score and the nodule’s size.

Goiter. The ultrasound confirms thyroid enlargement and helps identify the cause.

Lymph nodes. The cervical lymph nodes are examined for any enlargement or suspicious features that could suggest cancer spread.

Understanding Your Results

Thyroid nodules are extremely common. Research shows that ultrasound detects nodules in up to 50-60% of the general population, and the prevalence increases with age. The vast majority are benign.

Finding a nodule does not mean you have cancer. Studies have shown that only about 5-15% of thyroid nodules are cancerous. In one large study, cancer was found in fewer than 1 out of every 100 ultrasound-detected nodules.

Your radiologist will assign a TI-RADS category to each nodule and recommend the appropriate next step: no follow-up needed for clearly benign-appearing nodules, follow-up ultrasound in 1-3 years for mildly suspicious nodules, FNA biopsy for nodules that meet size and suspicion criteria, or urgent evaluation for highly suspicious findings.

Follow-Up After a Thyroid Ultrasound

Normal results. If your thyroid looks healthy, no additional testing may be needed. Your doctor may recommend periodic ultrasounds if you have risk factors.

Benign-appearing nodules. Your doctor may recommend monitoring with follow-up ultrasounds at 6 to 12 month intervals initially, then less frequently if the nodule remains stable.

Suspicious nodules. If a nodule has concerning features, your doctor may recommend a fine needle aspiration (FNA) biopsy. During this procedure, a thin needle is inserted into the nodule under ultrasound guidance to collect cells for laboratory analysis. The procedure is quick, performed in the office, and causes only mild discomfort.

Confirmed abnormalities. If biopsy confirms cancer or another condition requiring treatment, your doctor will refer you to the appropriate specialist. Thyroid cancer, when detected, is usually highly treatable with excellent outcomes.