If you’ve had a thyroid biopsy, you might have left with more questions than answers. What do the numbers mean? What is the Bethesda system? And most importantly, what do your thyroid biopsy results mean for your next steps?

Thyroid Biopsy Results: Breaking Down the Bethesda System

Why Your Thyroid Biopsy Results Matter

If you’ve recently had a thyroid nodule biopsy, you’re not alone. Thyroid nodules are extremely common, and most are harmless. But some can be cancerous or cause other problems, which is why we biopsy them in the first place.

The challenge? Many patients leave with confusing thyroid biopsy results filled with medical jargon. At the Clayman Thyroid Center, we believe you deserve to fully understand your results. When you understand what your biopsy is telling you, you can make the best decision about what comes next for your health.

That’s why doctors around the world use something called the Bethesda System. It’s a universal way of reporting thyroid biopsy results so that both patients and doctors are speaking the same language.

What Is the Bethesda System for Thyroid Biopsy Results?

The Bethesda System categorizes thyroid biopsy results into six categories, numbered 1 through 6. Each category has a specific meaning, and it helps your doctor decide whether you need more testing, surgery, or just monitoring.

Think of it as a traffic light system:

• Green: benign, nothing to worry about right now
• Yellow: uncertain, we need more information
• Red: suspicious or cancerous, we need to take action

Does everyone with a thyroid nodule need a biopsy?

No, not everyone with a thyroid nodule needs a biopsy. Many nodules are completely harmless and never cause problems. We usually start with an ultrasound to evaluate the size and appearance of the nodule. If the nodule looks suspicious or is larger than 1–1.5 cm, we typically recommend a fine needle aspiration (FNA) biopsy to determine if the cells are benign or cancerous. Smaller nodules or those that appear very low risk on ultrasound may simply be monitored over time with follow-up imaging instead of going straight to a biopsy.

Breaking Down Your Thyroid Biopsy Results: The Six Bethesda Categories

Bethesda Category 1: Nondiagnostic

If your thyroid biopsy results fall into Bethesda Category 1, it means there weren’t enough cells collected in the sample for the pathologist to make a clear diagnosis. This doesn’t necessarily indicate a problem; it simply means the test wasn’t able to provide enough information. The most appropriate next step is to repeat the biopsy so we can get a better sample. While it can be frustrating to do the test again, this is the only way to ensure you have an accurate diagnosis and can make informed decisions about your care.

Bethesda Category 2: Benign

A benign result is the outcome we hope for because it means the cells in your thyroid nodule look normal and the chance of cancer is very low—about 1%. If the nodule is smaller than 3.5 cm and isn’t causing compressive symptoms like difficulty swallowing or breathing, we can typically just monitor it with regular ultrasounds. If it is larger or causing discomfort, we may discuss surgery, but in most cases, no immediate intervention is needed.

Bethesda Category 3: AUS (Atypia of Undetermined Significance)

Category 3 is often called the “gray zone” because the cells don’t appear completely normal, but they also aren’t clearly cancerous. In this situation, we usually recommend additional molecular testing, which looks at the nodule’s genetic makeup to better assess the risk of cancer. Depending on those results, surgery to remove part of the thyroid may also be recommended so we can evaluate the tissue more thoroughly.

Bethesda Category 4: Follicular Neoplasm

When biopsy results show Bethesda Category 4, it means the cells could be part of a tumor, but the biopsy can’t tell us if the tumor is benign or malignant. This uncertainty makes it necessary to do more. Like Category 3, molecular testing may be recommended to get a clearer picture of the risk of cancer. In many cases, we advise surgery to remove part of the thyroid so that the entire nodule can be examined and a definitive diagnosis can be made.

Bethesda Category 5: Suspicious for Malignancy

Bethesda Category 5 indicates that there is a high chance—between 67% and 83%—that the nodule is cancerous. Because the likelihood of cancer is significant, surgery is typically recommended. Depending on the individual situation, this may involve removing at least half of the thyroid gland or, in some cases, a total thyroidectomy.

Bethesda Category 6: Malignant

A Bethesda Category 6 result is the most definitive: it means the biopsy clearly shows cancer. While this is never easy news to hear, it’s important to remember that most thyroid cancers grow slowly and have excellent cure rates when treated by an experienced thyroid surgeon. Surgery, usually a thyroidectomy, is the recommended treatment. At the Clayman Thyroid Center, we perform over 2,000 thyroid surgeries each year and consistently achieve some of the best cure rates in the world.

Why Thyroid Biopsy Results Can Be Confusing

Many patients expect their thyroid biopsy results to be a simple yes or no. Unfortunately, that’s not always the case. In fact, up to 30% of biopsies fall into the “indeterminate” categories (3 and 4).

This doesn’t mean something is wrong—it just means the cells don’t give us enough information. That’s why molecular testing and surgery are sometimes necessary for a definitive answer.

How We Help Patients Understand Their Thyroid Biopsy Results

At the Clayman Thyroid Center, we take extra time to walk you through your results. Here’s what you can expect:

1. A detailed review of your biopsy and ultrasound
2. A personalized plan based on your specific Bethesda category
3. Clear explanations of your options, whether that’s monitoring, further testing, or surgery

We want you to leave your appointment feeling empowered, not overwhelmed.

What If My Thyroid Biopsy Results Show Cancer?

If your biopsy shows cancer, it’s normal to feel anxious—but it’s important to know that thyroid cancer is one of the most treatable cancers when handled by an expert.

Our team at the Clayman Thyroid Center are world leaders in thyroid surgery. Each of our surgeons focuses exclusively on thyroid disease, which means you’re in the best hands possible. Our cure rates are among the highest in the world, and we’re known for making the process as easy as possible for our patients.

What If I Need Surgery After My Thyroid Biopsy Results?

If surgery is recommended, we make the process simple:

• You’ll have a consultation with one of our expert thyroid surgeons.
• We’ll review your ultrasound and biopsy to determine exactly what needs to be done.
• Many patients can have their evaluation and surgery on the same day at our state-of-the-art Hospital for Endocrine Surgery in Tampa, Florida.

Why Your Surgeon’s Experience Matters

If your thyroid biopsy results suggest surgery, it’s critical to choose a high-volume thyroid surgeon. This isn’t a procedure any surgeon should do occasionally. Experience matters when it comes to removing the thyroid safely and effectively.

At the Clayman Thyroid Center, each of our surgeons performs hundreds of thyroid operations every year. This expertise leads to better outcomes, fewer complications, and higher cure rates.

Thyroid Biopsy Results: Key Takeaways

1. Don’t panic. Most thyroid nodules are benign.
2. Understand your Bethesda category. This determines your next steps.
3. Ask questions. If something doesn’t make sense, speak up.
4. Seek expert care. Especially if your biopsy results are suspicious or cancerous.

We’re Here to Help
If your thyroid biopsy results are confusing, you don’t have to navigate this alone. At the Clayman Thyroid Center, we’ve helped thousands of patients understand their results and get the care they need.

We’re here to answer your questions, ease your fears, and guide you every step of the way.

Ready to talk about your thyroid biopsy results?
We’re here to help. Schedule a consultation with one of our expert thyroid surgeons today and get the clarity you deserve.

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Additional Resources

• Become our patient by filling out the form at this link. 
• Learn more about The Clayman Thyroid Center here. 
• Learn more about our sister surgeons at the Norman Parathyroid Center, and Carling Adrenal Center
• Learn more about the Hospital for Endocrine Surgery.