Fine Needle Aspiration (FNA) of Your Thyroid

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This information explains what to expect during and after your procedure for a fine needle aspiration (FNA) of your thyroid. This procedure is also known as a fine needle biopsy.

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About Your FNA Procedure

The thyroid gland is a small gland in the lower part of the front of your neck. Your thyroid makes hormones that control your metabolism (how your body breaks down food into energy).

A fine needle aspiration (FNA) is a procedure that uses a thin needle to take out cells from a nodule in your thyroid gland. Thyroid nodules are abnormal growths of tissue or fluid that may or may not be cancer. After your FNA procedure, the cells that were taken out are checked to see if they have cancer.

Your FNA procedure can be done in your healthcare provider’s office or at a local radiology center.

  • If you’re having your FNA done at Memorial Sloan Kettering (MSK), your healthcare provider’s office will help schedule this appointment.
    • On the day of your appointment, make sure you eat a light meal so you don’t feel dizzy and lightheaded (like you might faint). You don’t need to follow any special diet. Take all your usual medications too.
    • Tell your healthcare provider if you’re taking aspirin or any anticoagulant (blood thinner) medication, such as warfarin (Coumadin®), dalteparin (Fragmin®), or enoxaparin (Lovenox®). Your healthcare provider may tell you to stop taking your medication several days before your procedure.
  • If you’re having your FNA done at a local radiology center, your healthcare provider will give you a prescription. Check with the radiology 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 procedure, you’ll be lying down. Usually, your healthcare provider will do an ultrasound of your neck first. An ultrasound is an imaging scan that uses sound waves to create pictures of the inside of your body. Your healthcare provider will use the scan to see your thyroid gland and find the nodule.

Your healthcare provider will then place a thin needle through the skin in the front of your neck. They’ll use the needle to take cells out of the thyroid nodule. They may insert the needle at least 2 times to collect enough cells from the nodule. If your healthcare provider needs to take out cells from more than 1 nodule, they’ll use more needles.

Generally, you won’t need a local anesthetic for this procedure. A local anesthetic is a medication that makes an area of your body numb.

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What to Expect After Your FNA

You may have mild discomfort after your FNA. If you do, take acetaminophen (Tylenol®). If you can’t take acetaminophen, tell the healthcare provider who sent you for your FNA. They can suggest another medication.

You may also have some mild swelling after your FNA. If you do, put a cold compress (such as an ice pack or a cool washcloth) on the area. Do this for 20 minutes to help reduce the swelling. It’s important that you take the cold compress off for at least 20 minutes before you put it back on.

You don’t need to follow any special diet after your procedure. You may eat and drink as you usually 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 checked. It can take up to 1 week to get your FNA results. The healthcare provider who sent you for your FNA will call you when your results are ready. They may tell you your results over the phone or ask you to come in for an appointment.

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

  • Malignant (cancerous) cells. Depending on your FNA results, you may need surgery. If you don’t need surgery, your healthcare provider will talk with you about follow-up care.
  • Benign (not cancer) cells. Your healthcare provider will tell you how to monitor (keep track of) your nodule(s).
  • Cells that may be cancer. Your healthcare provider will tell you what needs to be done.
  • Inconclusive (unclear). Your healthcare provider won’t be able to tell if it’s cancer or not. They’ll tell you how to monitor your nodule(s).
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When to Call Your Healthcare Provider

Call the healthcare provider who sent you for your FNA if you have:

  • A fever of 101 °F (38.3 °C) or higher
  • Swelling, warmth, redness, or drainage around your biopsy site that’s getting worse

If you have trouble breathing, call 911.

If you need to see a healthcare provider right away, go to your local emergency room or to MSK’s Urgent Care Center (UCC). The UCC is on the 1stfloor of Memorial Hospital (MSK’s main hospital). The address is:

425 East 67thStreet
(between York and First Avenues)
New York, NY 10065

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