Fine Needle Aspiration of the Thyroid

Written by Tricia Kinman | Published on July 19, 2012
Medically Reviewed by George Krucik, MD

Fine Needle Aspiration of the Thyroid

The thyroid is an important organ in your endocrine system that releases hormones that regulate many of the functions in your body. The thyroid gland is found at the base of the neck, just below the Adam’s apple. Sometimes small nodules, or lumps, appear on the thyroid. When this happens, the doctor may order a test called fine needle aspiration (FNA), or fine needle biopsy, to obtain tissue samples from the thyroid for analysis.

When Is this Procedure Done?

Your doctor may order this test if you:

  • have had a persistent cough or unexplained sore throat for a long period
  • have nodules, or lumps, on your throat that you can feel or see
  • have lumps that appear on an ultrasound
  • have a history of thyroid cancer in your family
  • have a cyst, or fluid-filled lump, on your thyroid

By aspirating, or obtaining tissue from the site, your doctor will be able to see if the lump is cancerous or not. In 70 percent of the cases, the nodule is a benign, or harmless, tumor (Rothrock). If you have a cyst instead of a nodule, your doctor may perform fine needle aspiration to drain the cyst.

What Do I Do to Prepare for Fine Needle Aspiration?

While the test can be done in a hospital, you may have the procedure done in the physician’s office. You do not need to have a special diet or avoid any drinks or medications before the procedure. If you take a blood thinning medication, make sure to tell your doctor, as you may need to avoid taking it and other medications that thin the blood, such as aspirin and non-steroidal anti-inflammatory drugs (NSAIDs). Avoid wearing necklaces or any other jewelry that may interfere. If you are nervous or anxious about the procedure, discuss your concerns with the doctor. It is important that you are able to lie still for an extended period.

During the Procedure

Before the procedure begins, you may be asked to put on a gown. When the procedure begins, your doctor will ask you to lie down. You will feel a cold sensation as your neck is cleaned with iodine or another solution that kills any harmful germs that may be on your skin. In some cases, your doctor will use a local anesthetic to numb the area, but this is not always necessary. Next, your doctor will insert a small needle into the nodule. You should not talk, swallow, or move while this happens. Your doctor will repeat this a few times to make sure the sample is enough for the analysis.

After the Procedure

The procedure usually lasts about 20 minutes. After the procedure, your doctor will place some gauze over the area and apply pressure for several minutes to stop the bleeding. You may see a small bruise on the area within a day or two. The doctor may tell you not to take any medications that contain aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) for 24 hours (Rothrock).

Are There Any Risks?

Fine needle aspiration of the thyroid is generally safe. Still, there is a risk for some complications, such as (Mathur):

  • bleeding
  • infection
  • cysts

You may experience swelling, bruising, or slight pain, which is normal. Call you doctor if you develop a fever or continue to have swelling or more intense pain.


The tissue that was aspirated is usually sent to a lab for analysis. The results are usually available within one week. The results that come back will fall into one of four categories:

  • benign (not harmful)
  • suspicious (may be cancerous)
  • malignant (cancerous)
  • inadequate/indeterminate (unable to tell from the sample)

Your doctor will discuss the results with you and determine the next steps to take. If you have suspicious, malignant, or inadequate results, you may need to have further procedures done.

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