Thyroid ultrasound (USG) is an imaging test used to evaluate thyroid gland structure and detect nodules, cysts, or enlargement. It provides detailed visualization without radiation exposure.
Physicians request thyroid USG to investigate goiter, assess nodules, or monitor changes in patients with thyroid disease. It is also used in follow-up after surgery or interventional treatments.
The procedure involves placing a transducer on the neck, producing real-time images of the thyroid gland. It is painless, quick, and widely accessible in clinical practice.
Thyroid ultrasound is essential in differentiating benign from suspicious nodules. Combined with fine-needle aspiration biopsy, it plays a central role in thyroid cancer detection and management.
| Medical Name | Thyroid Ultrasonography (USG) |
| Purpose of Use | Assessment of thyroid gland size, structure, and nodule presence and features |
| Method Type | Imaging technique using sound waves, free from radiation |
| Procedure Duration | Typically 5–10 minutes |
| Preparation Requirement | No special preparation required; the patient simply lies on their back |
| Structures Evaluated | Thyroid lobes, isthmus, lymph nodes, vascular structures |
| Clinical Use Areas | Nodule screening, goiter evaluation, thyroid cancer follow-up, biopsy guidance |
| Possible Findings | Solid or cystic nodules, calcifications, parenchymal heterogeneity, lymphadenopathy |
| Advantages | No radiation, repeatable, low cost |
| Limitations | Provides only structural assessment; no functional information |
| Auxiliary Methods | Thyroid scintigraphy, blood tests, needle biopsy (can be performed under USG guidance) |
What Is a Thyroid Ultrasound and Why Is It Important?
Thyroid ultrasound is a test that uses sound waves to create images of your thyroid gland and other tissues in your neck. Since it does not use radiation, it is extremely safe. The most common reason for this test is to evaluate thyroid nodules, or lumps within the thyroid gland.
Thyroid nodules are quite common. Most are benign, but a small number may have a risk of cancer. Ultrasound allows us to see the structure of these nodules in detail and helps determine which ones need closer investigation (such as biopsy). Early diagnosis is crucial, especially for cancerous nodules, to ensure successful treatment.
How Does Thyroid Ultrasound Technology Work?
This technology is similar to sonar used by submarines or bats. A special device (transducer) sends sound waves—inaudible to the human ear—into your body. These waves bounce off your thyroid gland and return as echoes. The device collects these echoes.
The gel applied to your neck helps the sound waves pass more effectively through the skin. A computer analyzes the returning echoes and creates a live image of your thyroid on the screen. Throughout this process, you feel nothing and are exposed to no radiation, so the procedure can be repeated safely whenever needed.
When Should You Get a Thyroid Ultrasound?
Your doctor may recommend a thyroid ultrasound for several reasons. The most common is the detection of a swelling or lump in your neck during a physical exam. Ultrasound helps determine if the swelling is from the thyroid or another source.
If you already have a known nodule, or if a nodule was discovered incidentally, ultrasound helps analyze its characteristics (size, content, borders, etc.) in detail. It is also performed to monitor general thyroid enlargement (goiter) or to check for changes in known nodules over time. Ultrasound guidance is also used during procedures such as needle biopsy.
Is Any Special Preparation Needed for Thyroid Ultrasound?
Generally, no special preparation is needed for a thyroid ultrasound. There is no requirement to fast or follow a special diet. You can eat and drink normally.
Wearing comfortable clothes and choosing attire that leaves the neck area exposed will make the process easier. Remove necklaces or other jewelry from your neck before the test. Otherwise, the procedure is straightforward and simple.
Step-by-Step: How Is a Thyroid Ultrasound Performed?
The process is very simple. You lie on your back on an examination table. A small pillow may be placed under your shoulders for better visualization of the neck.
The technician or doctor applies a clear, water-based gel to your neck, which may feel a little cool but is harmless. The ultrasound probe (transducer) is then moved over the gelled skin. Images of your thyroid and surrounding tissues appear on the screen. You may be asked to turn your head slightly or swallow to improve the view. The procedure typically lasts 5–10 minutes. Afterwards, the gel is wiped off and you can immediately return to your daily routine.
Does a Thyroid Ultrasound Hurt?
No, thyroid ultrasound is not painful at all. No needles are used for diagnostic ultrasound. The only sensation is the coolness of the gel and the light pressure of the probe on your skin.
This pressure is generally not uncomfortable. If you do feel any pain for any reason, inform the person performing the procedure. Most patients tolerate this examination easily; it is simple and painless.
What Does a Normal Thyroid Ultrasound Report Show?
If your thyroid ultrasound result is normal, the report will state that the size, shape, and internal structure of your thyroid gland are normal. A healthy thyroid appears butterfly-shaped with right and left lobes connected by a thin bridge (isthmus), and smooth edges.
The internal structure is described as “homogeneous,” meaning the tissue appears uniform throughout. If the gland is enlarged, this is called “goiter.” The report will also mention if the lymph nodes around the thyroid appear normal. In summary, everything is described as having a typical appearance if normal.
What Are Common Abnormal Findings in Thyroid Ultrasound?
Ultrasound can reveal several abnormalities. The most common is “thyroid nodules”—small lumps within the gland that may be solid, fluid-filled (cystic), or mixed.
Another frequent abnormality is “goiter,” or enlargement of the thyroid gland, which may be diffuse (evenly enlarged) or nodular (single or multiple nodules). Simple cysts, which are fluid-filled and usually harmless, may be detected. “Thyroiditis” (thyroid inflammation, such as Hashimoto’s) also changes the ultrasound appearance—usually a darker, more irregular structure. Abnormal lymph nodes near the thyroid can also be an important finding.
What Features of Thyroid Nodules Are Evaluated by Ultrasound?
When a nodule is detected, several features are assessed: internal structure (solid or cystic), brightness compared to normal tissue (echogenicity), shape (especially whether it is taller than wide), border characteristics (smooth or irregular), presence and type of calcifications, and blood supply (using Doppler). Finally, whether the nodule extends beyond the thyroid gland is checked.
Why Is It Important to Assess These Features in Nodules?
Each of these features helps estimate the likelihood that a nodule is benign or malignant. No single feature is decisive, but a combination can suggest the overall risk. For example, a purely fluid-filled cyst is generally harmless, while a solid, dark, irregular nodule with microcalcifications is considered more suspicious. This detailed assessment guides whether a nodule only needs monitoring or if a biopsy is needed.
What Ultrasound Findings Raise Suspicion for Cancer?
Certain features raise the suspicion of malignancy: solid structure, significant hypoechogenicity (much darker than surrounding tissue), irregular or spiculated margins, a shape that is taller than wide, presence of microcalcifications (tiny, bright spots), extension beyond the thyroid, or abnormal nearby lymph nodes. If any of these features are seen, a biopsy is often recommended regardless of nodule size.
How Does Thyroid Ultrasound Help Assess Nodule Risk?
Because ultrasound provides so much detail, standard classification systems such as TI-RADS are used. These systems help radiologists score and categorize nodules according to ultrasound features (structure, brightness, shape, margins, calcifications), providing an estimated cancer risk and management recommendations (follow-up, biopsy, etc.). This allows for more consistent decisions and helps avoid unnecessary biopsies.
How Does Ultrasound Guide Needle Biopsy?
Fine-needle aspiration biopsy (FNAB) is usually performed on suspicious nodules. Ultrasound provides real-time guidance, so the needle can be accurately inserted into the most concerning part of the nodule. This increases diagnostic accuracy and safety by avoiding important neck structures such as blood vessels.
How Are Biopsy Results Interpreted?
The cells obtained are analyzed in a pathology lab and reported according to the Bethesda System. Results may be “benign” (most common, usually just monitored), “malignant” or “suspicious for malignancy” (usually requires surgery), “non-diagnostic” (not enough cells—biopsy needs repeating), or “indeterminate” (uncertain; may need further testing or follow-up).
Why Is Thyroid Ultrasound Used in Goiter?
Goiter is an enlarged thyroid gland. If goiter is suspected on exam, ultrasound is the best tool for confirmation and measurement. It also helps determine if the enlargement is diffuse or nodular, and if nodules are present, each can be individually assessed for cancer risk and monitored over time.
What Does Thyroid Ultrasound Show in Hashimoto’s Disease?
Hashimoto’s thyroiditis is an autoimmune disease. On ultrasound, the gland typically appears darker (hypoechoic), coarse, and heterogeneous. It may be enlarged (goiter) or atrophic, and often has multiple small nodules (micronodulation) and fibrotic bands. Blood flow may be increased on Doppler. These findings, along with blood tests and antibodies, support the diagnosis.
How Are Nodules in Hashimoto’s Disease Interpreted?
Sometimes, larger, distinct nodules appear within the inflamed gland. Inflammation alone may mimic nodule-like appearances, which can show suspicious features. However, since cancer risk is slightly increased in Hashimoto’s, all distinct nodules should be carefully assessed and, if suspicious, biopsied according to standard risk systems (like TI-RADS).
What Are the Advantages of Thyroid Ultrasound?
- Completely safe (no radiation), even for pregnant women
- Painless, noninvasive, easily repeatable
- Provides very detailed images of thyroid structure and nodules
- Guides procedures like biopsy in real time
- Widely available and cost-effective
What Are the Disadvantages or Limitations of Thyroid Ultrasound?
- Results depend on the experience of the operator and interpreting physician
- Only shows structure, not function (cannot measure hormone production)
- Very sensitive—may detect small, clinically insignificant nodules, leading to unnecessary anxiety or further tests (“overdiagnosis” risk)
- Rarely, a benign-appearing nodule can be malignant, or a suspicious one may be benign
How Is Benign Nodule Follow-Up Done by Ultrasound?
If a nodule has been biopsied and found to be benign, it is typically not operated on but monitored with regular ultrasound exams. The first follow-up is usually in 1–2 years. The goal is to check for significant growth or changes. If the nodule remains stable for several years, follow-up intervals may be extended to every 3–5 years. Long-term follow-up duration is decided on an individual basis with your doctor.
Interventional Radiology and Neuroradiology Speaclist Prof. Dr. Özgür Kılıçkesmez graduated from Cerrahpaşa Medical Faculty in 1997. He completed his specialization at Istanbul Education and Research Hospital. He received training in interventional radiology and oncology in London. He founded the interventional radiology department at Istanbul Çam and Sakura City Hospital and became a professor in 2020. He holds many international awards and certificates, has over 150 scientific publications, and has been cited more than 1500 times. He is currently working at Medicana Ataköy Hospital.
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