Fine needle aspiration of the thyroid
Fine Needle Aspiration (or FNA) is the technique by which a few cells of the thyroid are taken using a fine needle (similar to the one used to take blood from you) using the guidance of the ultrasound machine. The cells taken will be seen under the microscope by a trained doctor (histopathologist) who will comment on the chance that there may be thyroid cancer.
What is FNA (Fine Needle Aspiration)?
FNA is the technique by which a small needle is used in order to take a few cells from a suspicious area/nodule of the thyroid. To increase the accuracy of the technique the needle will be guided to the appropriate area using an UltraSound scan. It is common practice to take cells from several area, meaning that there will be several attempts to insert the needle in the nodule.
In our centre, our practice is to have two doctors performing the procedure (an Endocrinologist and a Radiologist) in order to increase the accuracy of the procedure.
Once these cells are taken, they are applied in a glass slide, and are examined under the microscope by a doctor trained to assess cells seen through the microscope (known as histopathologist). A result giving the CHANCE of cancer (and NOT THE SEVERITY of cancer) will be given (see last page to see the classification by which the results are given)
Why do I need a thyroid Fine Needle Aspiration
FNA is required when an UltraSound scan has been performed on your thyroid and a nodule has been identified to have some suspicious features. Such features DO NOT mean you have cancer. It simply means that the nodule needs to be further investigated to be sure that it is benign (i.e. normal).
What are the “suspicious” features on my UltraSound Scan?
The following features are considered “suspicious” features during a thyroid UltraSound scan:
Calcificationwithin a nodule (seen as white spots)
Irregular marginsof the nodule
The heightof the nodule is bigger than the width
Increased blood supplywithin the nodule (seen during a colour Doppler UltraSound Scan)
Enlarging size of the nodule
If one or more of the above features are seen during an UltraSound Scan of the thyroid, an FNA is recommended.
What is the difference between a biopsy and FNA?
There is a huge difference between the two, with the FNA having a lot of inaccuracy:
As the cells from the suspicious area are taken by a small needle, there is a small alteration in their structure making their assessment more difficult
The sample is often blood stained and might have small clots due to the increased vascularity of the nodule, which also makes their assessment more challenging
FNA only takes a few cells from the nodule, leaving behind the majority of the cells that makes up the nodule. As such, only a small sample is examined which makes it more difficult to have the full picture of what makes up the nodule
BIOPSY of the nodule
This is only possible if the whole nodule is removed surgically. An accurate biopsy of the nodule can ONLY be performed once the thyroid (or half the thyroid) is removed and the nodule assessed carefully.
As the whole nodule is removed in a biopsy, it is able to be cleaned and remove all blood, making its assessment much easier
The nodule is cut in special small slices and therefore we are able to assess the nodule in its entire structure (i.e. beginning to end) and therefore giving a very big accuracy of the result
How long will it take for the result of the FNA to come out?
We understand that having an FNA of a suspicious thyroid nodule is a stressful period for you. We take this into consideration and we make every effort to emphasize this to the histopathologist who will examine the nodule.
We have agreed a result to come out within48hours, primarily due to the preparation required for the samples we sent. It is possible however to have the result within 24hours.
Explanationof your results
The FNA result will be in a "coded" system, denoting the CHANGE of malignancy and NOT the severity of any malignancy (if this is present of course).
The Table below summaries the categories of the FNA result and what each result means: