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.
What Can You Expect During Your FNA?
You may have your test sitting up, but many practitioners will begin by having you lie down on the examining table. You'll be asked not to swallow, talk, or move while the aspirations are taking place.
The needle is fairly small and fine. Some practitioners use a needle with a handle. According to Dr. Oertel, these types of needles -- sometimes known as a syringe pistol -- are preferable. (Click here to see a syringe pistol.) The handle allows the practitioner to leave one hand free to feel the neck and nodule, and ensure that the needle doesn't move around, but rather, is guided right into the nodule to be tested. With a handle-less needle, many practitioners have to use both hands to insert the needle, which can be a factor for error, as the pathologist may not be able to accurately aim the needle into the nodule without a free hand to guide it.
The entire procedure shouldn't take more than a ten to twenty minutes. Most practitioners peform two to four aspirations on every nodule of concern. In her presentation at ThyCa 2000, Dr. Oertel mentioned that she takes a minimum of three samples, from the center, bottom and top of the lump, and sometimes several more, depending on her judgment as to the quality of the samples.
Many practitioners advise that you apply pressure to the area for approximately 20 minutes after the aspiration in order to minimize bruising or swelling.
Will It Hurt?
That depends on the skill of the practitioner, your own perceptions of pain. Some practitioners will use lidocaine, a local anesthetic, to numb the injection site. But patients complain that this can hurt more than the actual FNA procedure. Other practitioners don't use anesthetic. At ThyCa 2000, Dr. Oertel discussed that she does not use an anesthetic, she prefers to use an ice pack to numb the skin. Her rationale - an anesthetic needle creates a lump - some swelling - around the injection site that can interfere with the ability to get an accurate sample.
How Will it Feel Afterwards?
You might have slight pain with some swelling and bruising at the injection locations, and possibly slight discomfort in swallowing. Ask your doctor about recommendations regarding post-FNA pain medication - many recommend taking acetominophen or ibuprofen as directed to minimize any residual discomfort.
Can You Go Back to Work?
Most people are comfortable enough to go back to work the same day or next day after having an FNA.
But you should avoid vigorous physical activity, sports for approximately 24 hours after the FNA.
What Kind of Results Can You Expect?
A nodule is more likely to be cancerous if it falls into certain risk factors:
Ultimately, however, approximately 5% of all thyroid nodules are cancerous.
- Larger nodules - over 4 centimeters, are more likely to be cancerous than nodules less than 4 centimeters
- Men's nodules are more likely to be cancerous than women's nodules
- A solitary nodule is more likely to be cancerous than nodules found in a "multinodular" thyroid
- Nodules in a person younger than 20 or older than 70
- History of external neck irradiation during childhood
- "Cold" characterization on ultrasound - meaning that the nodule does not absorb iodine or make thyroid hormone
The results from your FNA will fall into the following breakdown:
|Suspicious ||10% |
What If It's Benign?
If you have a benign nodule, your doctor will likely treat the nodule, typically using thyroid hormone to help shrink the nodule.
What If It's Malignant/Cancerous?
If you are diagnosed with thyroid cancer, your first stop should be the following article, An Introduction to Thyroid Cancer, which is a good starting point for information about thyroid cancer, including papillary, follicular, medullary and
anaplastic cancer, including support groups and followup treatments.
What If It's Suspicious?
Typically, a second test will be conducted. But most suspicious nodules usually result in thyroid surgery. An estimated 25 percent of those nodules labeled suspicious are found to be malignant with surgery.
What If It's Nondiagnostic?
If you get a nondiagnostic sample, you will need to wait a month before retesting, otherwise, it's likely that the only thing aspirated will be a blood around the site of the initial aspiration.
Can You Have a False Diagnosis?
False results, such as false negatives showing your FNA results are benign when they are actually cancerous, or false positives showing a benign nodule as malignant, are more common than you think. Some experts estimate that an average of approximately 2 to 4% of all FNAs may be false results.
Do You Need a Second Opinion?
If you have a negative result, but have risk factors for or family history of thyroid cancer, in particular, you should consider getting a second opinion on your FNA. And, if you have a positive result indicating cancer, a second opinion is also important. You may feel uncomfortable about mentioning this to your doctor, or feel that it will be perceived negatively by your doctor, but, as Dr. Oertel said in her presentation to the ThyCa conference, "Get a second opinion. My ego will recover, but you might not!"
Where Can You Get More Information on FNA?