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Fine Needle Aspiration FNA Biopsy of the Thyroid

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Updated June 02, 2014

Mature Woman at doctors office. Doctor is doing an external gland exam, touching her glands with hands, using latex gloves.
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The most common method for evaluation of a suspicious thyroid nodule is a technique known as fine needle aspiration, or FNA.

In an FNA, a very fine, thin needle is inserted into the thyroid, and aspirates (or "suctions") cells and/or fluid from a thyroid nodule or mass into the needle. The sample obtained can then be evaluated for the presence of cancerous cells.

How Does FNA Differ From Needle Core Biopsy?

In a needle core biopsy, a thicker, large needle is used to obtain a "core" tissue sample for analysis, and the larger sample that can be recut for smaller samples that can be sent out for further analysis. Needle biopsies are typically done using local anesthesia, and these procedures have slightly greater risk of bleeding associated with them, so they are more often done by a surgeon in outpatient or ambulatory surgical facilities.

If an HMO or community does not have practitioners with expertise in performing FNA, or there are not cyopathologists available to do the unique form of interpretation needed for FNA results, patients are likelier to have a core needle biopsy, as this procedure, while more invasive for patients, requires less skill to obtain a valid sample, and less skill for pathologists to read and interpet.

Who Should Perform an FNA?

Typically, FNAs are done by by endocrinologists, cytopathologists, or surgeons. The cells are studied and assessed by a cytopathologist.

Make sure that the practitioner has extensive experience in doing fine needle aspirations. Ask how many aspirations the practitioner does each month, and ask their "unsatisfactory" or "inconclusive" specimens rate. Don't always assume an endocrinologist is particularly skilled in this technique - he or she may not regularly perform this procedure.

The rate of non-diagnostic or unsatisfactory specimens - samples that cannot be used for laboratory assessment, and must be redone -- can be high for some less experienced practitioners. Yolanda Oertel, M.D., a cytopathologist from the Washington Hospital Center who spoke about FNA at the September 2000 Thyroid Cancer Survivor's Association (ThyCa) Conference in Washington, DC, cautions patients to find out the rate at the facility where their aspiration is taking place. The average can run from 5% to 15%. Dr. Oertel, whose practice focuses on thyroid and breast aspirations, and who aspirates approximately 90 thyroids each month, has a "non-diagnostic" rate is less than 0.5 percent.

Where Is an FNA Performed?

Many FNAs are performed in a doctor's office, although some might be done as outpatient surgery.

At ThyCA 2000, however, Dr. Oertel recommended that patients not get an FNA outside a hospital setting. While the procedure is generally safe, and things seldom go wrong, there is a very small risk of hermorrhage, but that could be quickly treated in a hospital setting.

What is an Ultrasound-Guided FNA?

When a nodule is palpable - meaning, you can feel it with your hand - most practitioners don't need to use ultrasound to guide the FNA process.

Some nodules are very low lying or can only be felt when you are swallowing, or can't be felt but were picked up by ultrasound, cat scan or MRI. In these cases, a practitioner may use ultrasound to ensure that the FNA is accurately performed.

Is FNA Risky?

Thyroid FNA is generally considered safe, and almost never results in any complications.

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