Fine Needle Aspiration (FNA) of Your Thyroid

This information explains the fine needle aspiration (FNA) procedure of your thyroid.

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About Your FNA Procedure

A fine needle aspiration uses a thin needle to remove cells from a nodule in your thyroid gland. Thyroid nodules are abnormal growths of tissue and fluid that may or may not be cancer. After your FNA procedure, the cells that were removed are checked to see if they have cancer. This procedure is also known as a fine needle biopsy.

Your FNA can be done in your doctor’s office with a tiny needle or at a radiology department or center where an ultrasound (use of sound waves to take pictures of the inside of your body) can be used to guide the needle. In most cases, you won’t need local anesthesia (medication to make the area numb).

  • If you have your FNA done at Memorial Sloan Kettering (MSK), your doctor’s office will help arrange this appointment. You may take your medication as usual and eat a light meal before your FNA. You do not need to stop taking your blood thinning medication or aspirin before your procedure.
  • If you have your FNA done at a local radiology center, your doctor will give you a prescription. Check with the center about what instructions they want you to follow before the procedure.
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What to Expect During Your FNA

During your FNA, you will be lying down. An ultrasound of your neck is usually done first to see your thyroid gland and find the nodule. Your doctor will then place a thin needle through the skin in the front of your neck to take cells out of the nodule.

Your doctor may place the needle at least 2 times to gather enough cells from the nodule. If more than 1 nodule needs to be examined, your doctor will use more needles.

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What to Expect After Your FNA

After your FNA, you may have some discomfort and swelling. You can take extra strength acetaminophen (Extra Strength Tylenol®). If you aren’t able to take acetaminophen, tell your doctor. They can suggest another pain medication. You can also apply a cold compress on the area if you’re still uncomfortable.

There are no dietary restrictions for after your procedure. You may eat and drink as you normally do.

If you have your FNA done at MSK, read the resource What to Expect After Your Fine Needle Aspiration at MSK’s Fine Needle Aspiration Biopsy Clinic for more information.

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Your FNA Results

The cells taken during your FNA are sent to a lab to be examined. It takes 4 to 5 business days to get the results. Your doctor may discuss the results over the phone with you or you may need to make an appointment to discuss them in the office.

The types of cells that may be found in your nodule include:

  • Malignant (cancerous) cells. You will probably need surgery.
  • Benign (not cancer) cells. Your doctor will tell you how your nodules should be monitored.
  • Cells that may be cancer. Your doctor will tell you what needs to be done.
  • Inconclusive. Your doctor won’t be able to tell if it’s cancer or not. They will tell you how your nodules should be monitored.
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When to Call Your Doctor or Nurse

Call your doctor or nurse if you have:

  • A fever of 101°F (38.3°C) or higher
  • Shortness of breath
  • Swelling or redness that seems to be getting worse
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