By Dr. Lindsey VanDyke, DO, FACOI, FEAA
Board Certified Endocrinologist | Specializing in obesity, diabetes, thyroid care, and menopause management
Why a biopsy may be recommended
When a thyroid nodule is found, the big questions are: Is it risky? Could it be cancer? What’s the next step?
That’s where a biopsy , specifically a fine needle aspiration (FNA) , comes in.
“We’ve talked about risk factors, TIRADS scores, and exposures to radiation,” explains Dr. VanDyke. “But the biopsy is how we actually look at the cells and find out what we’re dealing with.”
The FNA is a minimally invasive procedure that collects a small sample of cells from the nodule for analysis.
Step-by-step: How a thyroid biopsy works
1. Positioning the patient
You’ll lie on your back with a neck roll under your shoulders.
“We want that neck extended , it really brings the thyroid to the front so it’s easier to find and target the nodule,” says Dr. VanDyke.
2. Numbing the area
A small amount of lidocaine (local anesthetic) is injected into the skin and the capsule around the thyroid.
“That’s where all the nerves are, so we block that area just like the dentist does for a cavity fill,” she explains. “For most people, the lidocaine is the worst part–like a bee sting–the rest is just pressure.”
3. Using ultrasound guidance
The ultrasound machine stays on during the whole procedure so the needle can be precisely guided into the right spot.
“We avoid cystic or sparse areas and aim for the outer edges of the nodule , that’s where we get the most cells,” Dr. VanDyke says.
4. Collecting the samples
A very fine needle (smaller than a typical blood draw needle) is inserted, and suction is applied while gently twisting the needle to collect cells. This is repeated 4–6 times depending on what’s retrieved.
5. Saving a “back pocket” sample
One pass is stored in a special solution called Veracyte.
“If the pathologist sees something unclear, like atypia of undetermined significance, we send that sample for genetic testing to look for high-risk genes,” Dr. VanDyke explains.
What the results can show
Pathologists may report one of four main outcomes:
- Benign – No signs of cancer; ongoing monitoring is recommended.
- Malignant – Cancer cells are present; treatment planning begins.
- Non-diagnostic – Not enough cells to make a conclusion (happens in 10–15% of cases).
- Atypia of undetermined significance (AUS) – Cells look unusual but it’s not clear that they’re “bad”; genetic testing may help clarify.
Results typically come back within about a week.
What patients usually feel
Most patients report only mild discomfort:
“Once the lidocaine is in, patients really just feel pressure,” says Dr. VanDyke. “It’s not fun, but when it’s done well, it’s quick and low-risk.”
Why this matters
A biopsy is the most reliable way to determine if a thyroid nodule is harmless or needs treatment. It allows for earlier, more precise decisions , whether that means watchful waiting, minimally invasive therapy, or surgery.
“A biopsy gives us the roadmap,” Dr. VanDyke says. “It takes the guesswork out and lets us make the best, safest plan for you.”
Take charge of your endocrine health, no matter where you live
Your health is your greatest asset , empower yourself by knowing who is in charge of it. Whether it’s your thyroid, diabetes, menopause symptoms, or other hormone concerns, getting care from a physician who listens and explains your options clearly makes all the difference.
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