Also available in PDF format:  Thyroid FNA

What is a thyroid FNA?

The thyroid is a gland in the anterior (front) part of the neck. FNA stands for fine needle aspiration. In a thyroid FNA, the doctor uses a very thin needle to take small tissue samples from the thyroid gland. The pathologist (a doctor who examines cells and tissues to diagnose diseases) will examine these tissue samples under a microscope and make a diagnosis.

How should I prepare for the FNA?

• If you normally take aspirin, stop taking it 5 days before your FNA.
• If you normally take an anticoagulant medicine (blood thinner), ask your doctor if you should stop taking it before your FNA.  Patients are advised to stop taking blood thinners 7 days before this procedure unless your doctor tells you otherwise.
• Wear loose-fitting, comfortable clothing.
• You do not need to fast before your FNA.

How is the procedure done?

In the exam room, you will change into a gown so that the cleaning solution used on your skin does not stain your clothes. You will then lie on your back on a comfortable exam table.
First, warm gel is applied to the skin on the front of your neck. The technologist (sonographer) then presses a hand-held device called a transducer against your skin in that area.
The transducer makes ultrasound waves and then receives the echoes from the body’s tissues. These echoes form pictures of the tissues that are being studied. These pictures appear on a computer screen. The radiologist (a doctor who interprets ultrasound and other imaging techniques) uses the pictures to see the thyroid gland and guide the needle during the FNA.
The nodule will be located, and the radiologist will decide the best way to reach it with a needle to get a tissue sample.
A blue disinfectant called ChloraPrep will then be applied to your skin where the FNA needle will be inserted. The area around your neck will be draped with sterile towels to create a germ-free working space.
The anesthetic lidocaine (a painkiller) will be injected into the tissues leading to the nodule. The injections may be uncomfortable until the area is numb, similar to how it feels getting novocaine injections before a dental procedure. 
Once the area is numb, a small needle is inserted into the nodule and moved slightly up and down within the nodule. This is the “aspiration” part of the procedure. By moving the needle slightly, cells from the nodule are caught inside the needle and can be removed. 
Each aspiration lasts about 10 to 15 seconds. Usually 4 aspirations are done to get enough tissue to sample. The samples are given to a pathologist. The pathologist will decide within 10 to 15 minutes if there are enough cells to make a diagnosis. If we need more cells, we will do 2 more aspirations.

What will I feel during the scan?

You will feel the sonographer apply warm gel to your neck and press the transducer against your skin. The transducer will be pressed against your skin during the entire FNA procedure, since the ultrasound is used both to find the nodule and to show where the needle is moving.
You will feel a small stick and “burn” as the anesthetic is injected into your neck. Once the area is numb, most patients report feeling “pressure” during the FNA.
After the procedure is done, your neck will be cleaned with warm water. You will be given a Band-aid and a small ice pack to hold on your neck for about 30 minutes. Some patients may have mild swelling and bruising after the FNA.

Who interprets the results and how do I get them?

The radiologist who specializes in ultrasound will review the pictures and send a report to your referring doctor to confirm that the FNA was done. The pathologist will interpret the FNA results and send a report to your doctor who referred you for the test. Your referring doctor will give you your test results.