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Fine Needle Aspiration

Fine needle aspiration (FNA) is also known as the ultrasound-guided fine-needle aspiration of the thyroid or image-guided thyroid biopsy. This article will help you to understand why you have been referred for an FNA, how to prepare for the test, what’s involved with the testing process and what to expect after the procedure.

What is a Fine Needle Aspiration of the Thyroid?

Fine needle aspiration of the thyroid is a procedure where a very fine, hollow needle is inserted into the thyroid to remove samples for testing (a biopsy).

Why is it performed?

A fine-needle aspiration (FNA) of the thyroid is performed to see what type of cells are within a lump or nodule within the thyroid and whether they are cancerous or not.1 The results of the test will determine the best course of treatment. Cells are removed and then examined under a microscope to establish if the mass is benign or malignant.

Where is it usually performed?

A fine-needle aspiration (FNA) would be carried out at a hospital, usually in the endocrinology or radiology department.  It is a minimally invasive procedure that does not require a general anaesthetic.

How do I prepare?

In preparation for your FNA, you may be asked to temporarily stop taking certain medication, such as anticoagulants, which could impact the procedure.

It is important to feel comfortable so we would advise wearing loose, comfortable clothing.  Ensure your clothing is not tight around your neck and is easy to remove as you may be asked to wear a hospital gown while the biopsy takes place.

The FNA biopsy does not require a general anaesthetic so you do not need to be accompanied unless you would prefer to have someone with you.  You should be able to drive and return to your normal daily activities straight after the procedure.

How long does it take?

An FNA usually takes around 30 minutes.

Is it painful?

A local or topical anaesthetic is sometimes applied to minimise any pain or discomfort.  Some discomfort/bruising may be felt afterwards at the site of the procedure.  You may also find it harder to swallow directly after the test. Over-the-counter pain medication and ice packs are advised as post-treatment remedies to reduce any after-effects. You should feel well enough to resume your normal daily activities straight after the biopsy.

What happens during the procedure?

You may be asked to wear a hospital gown for the procedure.

It is important to remember that the doctors carrying out your FNA are there to answer any questions you might have at any time and to ensure you remain as comfortable as possible. If you have any questions, this is the time to ask them.

Once in the treatment room, you will be asked to lay back on the bed with a pillow to support your shoulders. You will be required to tilt your head backwards to enable the doctor to access the thyroid gland.  Your neck will be cleansed and a local/topical anaesthetic may be applied. It is essential that you remain still, avoid swallowing, speaking, coughing or moving.  The doctor will hold the lump with one hand and insert the needle into the lump.

You may feel some pressure at this point but if you have had an anaesthetic this should reduce any pain.  An ultrasound machine is sometimes used to help guide the needle safely into the lump/nodule enabling cells to be removed for further testing. You are not exposed to any radiation during this process.

What are the possible side effects?

It is likely that you will feel some post-treatment pain and bruising at the site of the biopsy. You may also suffer from a sore throat, discomfort when swallowing and a croaky voice directly after the procedure. It is important that you contact your doctor if you experience any of the following side effects:

    • the lump getting bigger in size

    • the lump feeling harder

    • additional lump/s developing

    • difficulties breathing or swallowing

    • bleeding at the site of the biopsy

    • a continued hoarse voice/difficulty speaking

    • any evidence of an infection at the site of the biopsy

What do the results mean?

Results may take up to 2–3 weeks to be received. The majority of thyroid lumps tested are benign.  Some tests (approx. 5%) show inconclusive or suspicious results – your doctor will advise you regarding the next steps if this is the case with your biopsy results.

It is important to note that if results are positive for cancerous cells, most thyroid cancer cases can be successfully treated.  This may involve an operation to remove part or all of your thyroid gland. Your doctor will discuss your personal treatment plan with you.


  1. Thyroid Lumps
  2. Ultrasound – Thyroid


Date updated: 23.03.21 (V1.2)
Review date: 14.11.21

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