Fine Needle Aspiration (FNA) Biopsy of the Breast

If other tests show you might have breast cancer, your doctor may refer you for a fine needle aspiration (FNA) biopsy. During this procedure, a small amount of breast tissue or fluid is taken from the suspicious area and is checked for cancer cells.

What is an FNA breast biopsy?

In an FNA biopsy, the doctor uses a very thin, hollow needle attached to a syringe to withdraw (aspirate) a small amount of tissue or fluid from a suspicious area. The biopsy sample is then checked to see if there are cancer cells in it.

If the area to be biopsied can be felt, the needle can be guided into it while the doctor is feeling it. 

illustration showing a fine needle aspiration using ultrasound including detail of the biopsy needle, area to be biopsied and the ultrasound transducer

If the lump can't be felt easily, the doctor might watch the needle on an ultrasound screen as it moves toward and into the area. This is called an ultrasound-guided biopsy.

What should you expect if you have an FNA?

During an FNA

An FNA is an outpatient procedure most often done in the doctor’s office. Your doctor might use a numbing medicine (called a local anesthetic), but it's not needed in all cases. This is because the needle used for the biopsy is so thin that getting an anesthetic might hurt more than the biopsy itself.

You’ll lie on your back for the FNA, and you will have to be still while it’s being done.

If ultrasound is used, you may feel some pressure from the ultrasound wand and as the needle is put in. Once the needle is in the right place, the doctor will use the syringe to pull out a small amount of tissue and/or fluid. This might be repeated a few times. Once the biopsy is done, the area is covered with a sterile dressing or bandage.

Getting each biopsy sample usually takes about 15 seconds. The entire procedure from start to finish generally takes around 20 to 30 minutes if ultrasound is used.

After an FNA

Your doctor or nurse will tell you how to care for the biopsy site and what you can and can’t do while it heals. Biopsies can sometimes cause bleeding, bruising, or swelling. This can make it seem like the breast lump is larger after the biopsy. Most often, this is nothing to worry about, and the bleeding, bruising, and swelling go away over time.

What does an FNA show?

A doctor called a pathologist will look at the biopsy tissue or fluid to find out if there are cancer cells in it.

  • If the fluid is brown, green, or tan, the lump is most likely a cyst, and not cancer.
  • Bloody or clear fluid can mean either a cyst that’s not cancer or, very rarely, cancer.
  • If the lump is solid, the doctor will look at small groups of cells from the biopsy to determine what it is.

The main advantages of FNA are that it is fairly quick, and the skin doesn’t have to be cut, so no stitches are needed and there is usually no scar. Also, in some cases it’s possible to make the diagnosis the same day.

An FNA biopsy is the easiest type of biopsy to have, but it can sometimes miss a cancer if the needle does not go into the cancer cells, or if it doesn't remove enough cells. Even if an FNA does find cancer, there might not be enough cancer cells to do some of the other lab tests that are needed.

If the results of the FNA biopsy do not give a clear diagnosis, or your doctor still has concerns, you might need to have a second biopsy or a different type of biopsy.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Joe BN, Esserman LJ. Breast Biopsy. 2019. UpToDate. Accessed at on August 26, 2019.

Radiological Society of North America. Ultrasound-Guided Breast Biopsy. 2019. Accessed at on August 26, 2019.

Last Medical Review: September 1, 2017 Last Revised: October 9, 2017

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