Fine Needle Aspiration (FNA) Thyroid Biopsy

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Your child’s doctor or health care provider saw or felt a bump (nodule) on their thyroid. They need a fine needle aspiration (FNA) biopsy to know if the nodule is harmless (benign) or needs treatment. Bumps on the thyroid are common and usually not serious.

  • An interventional radiologist, a doctor who specializes in doing FNA’s, will use a needle to take fluid for testing from inside the nodule(s).
  • Your child should not feel pain. They will get numbing medicine at the site of the biopsy.
  • Some children may get sedation, a medicine that puts them to sleep, if they can’t stay calm during the procedure.
  • The test takes 30 minutes to 1 hour to do.
  • If your child has a fever, stuffy nose, or cough, the test may be rescheduled.

How to Prepare for the Test

  • You will get written instructions on how to prepare for the test.
  • If your child is getting numbing medicines, there’s nothing special to do at home.
  • If your child is getting sedation, a nurse will call the day before to tell you when to arrive and to review the nothing by mouth (NPO) instructions. Your child will need to stop eating and drinking certain things before the test.
  • Be sure to tell your health care team if your child has any allergies. 

The Day of the Test

  • If your child will get numbing medicines, arrive 1 hour before the test. A nurse will put numbing cream on the biopsy site. It takes 1 hour for the cream to work. 
  • If your child will get sedation:
    • You’ll meet with the pain medicine doctor (anesthesiologist) before the test starts.
    • A nurse will start an intravenous (IV) line. This is a tiny plastic tube that goes through the skin and into a vein. The nurse can put numbing cream on the skin where the IV goes in if needed.
  • Go to the Crossroads Lobby in the Main Hospital to register. You will get a map to the Procedure Center. A parent or legal guardian must be present to sign consent forms for the biopsy and sedation.
  • Sometimes the test schedule runs late or gets delayed.

The Biopsy Procedure

  • Your child will lie on their back on a padded table with rolled towels under their shoulders. Their head will be tipped back.
  • The doctor or health care provider will clean the skin over the thyroid.
  • If your child got numbing cream, the doctor or health care provider will put (inject) a different numbing medicine under the skin using a small needle.
  • Once the area is numb, the doctor will use a different small needle to get into the nodule(s). An ultrasound will help guide the needle to the right place.
  • The doctor will remove a small amount of fluid from the nodule. They may do this a few times until there’s enough fluid for the test.
  • They will clean, dry, and cover the biopsy site with a bandage.

Risks and Side Effects

  • There may be bleeding from the biopsy site. It’s normal to have some bruising.
  • Your child’s neck and throat may hurt for 1 to 2 days. This is normal.
  • Infections can happen. These are rare. If your child has a problem with their immune system or a heart problem, their doctor or health care provider will order antibiotics to prevent infection.
  • IV sedation medicine can slow down breathing during the procedure. We will watch your child closely.

After the Procedure

  • The biopsy site will stay numb for a little while after the procedure.
  • If your child was sedated, they could be clumsy and unsteady walking until the medicine wears off.
  • Your child:
    • Can drink clear liquids, like water or apple juice, soon after the procedure.
    • Will go back to their hospital room if they were already hospitalized.
    • Can go home if the procedure was done as an outpatient. They will go to their car, carried by their parent or guardian. If sedated, they will go to their car in a wheelchair.
  • At home, they:
    • They may eat their usual foods.
    • Can return to normal activities within a few hours. However, they need to avoid riding a bike, playing sports, or doing things that need them to be very focused for the first day at home.
    • Must keep their bandage on for 24 hours.
    • May take acetaminophen (Tylenol®) or ibuprofen (Motrin® or Advil®) for pain or discomfort. Read the label to know the right dose for your child’s age and weight.
  • It takes 2 to 7 days for the lab to send the biopsy results to the doctor or health care provider who ordered the test. We will call you to make a follow-up appointment when we get the test results.

When to Call the Doctor

Complications are rare. Call your child’s doctor or health care provider if they have:

  • Redness, swelling, or discharge from the biopsy site.
  • A temperature of 101° Fahrenheit (F) or 38.3° Celsius (C) or higher.
  • Pain or soreness lasting more than 72 hours.


Fine Needle Aspiration (FNA) Thyroid Biopsy (PDF)
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