Patient Basics: Fine-Needle Aspiration (FNA) of the Breast

Fine-needle aspiration (FNA) of the breast uses a very thin needle to draw fluid or cells out of a breast lump. If the lump is a fluid-filled cyst, draining it often makes the lump disappear on the spot. If the lump is solid, the cells are sent to a lab to check for cancer. It takes only a few minutes in a clinic, and most lumps checked this way turn out not to be cancer.

Key points

• “Aspiration” means drawing something out with gentle suction through a needle.
• FNA is most useful for breast cysts and for checking swollen lymph nodes in the armpit.
• For solid lumps, many doctors now prefer a core needle biopsy, which takes slightly larger samples.
• Most people feel only a brief sting or pressure.
• Results for cells sent to the lab usually take a few days to a week.

Why fine-needle aspiration is done

Your doctor may suggest FNA when:

• You or your doctor feel a new lump in the breast
• A mammogram or ultrasound shows a cyst or other spot that needs a closer look
• A cyst is large or painful and you want it drained
• A lymph node in the armpit looks swollen or unusual on ultrasound
• A pocket of infection (abscess) needs to be drained

Breast cysts are very common, especially between about age 35 and menopause. They often feel smooth and movable, and they can get bigger or more tender before a period. A simple cyst is not cancer and doesn’t raise your risk of breast cancer.

FNA or core needle biopsy?

A core needle biopsy uses a slightly larger hollow needle to remove thin strips of tissue rather than loose cells. That gives the lab more to work with. It can show the exact type of a cancer and whether it responds to hormones, which an FNA often can’t. Many breast centers use FNA for cysts and lymph nodes, and core biopsy for solid lumps. Your doctor will choose the test that fits your situation.

Before the test

• You can usually eat, drink and take your normal medicines.
• Tell your doctor if you take a blood thinner or aspirin, or have a bleeding problem. Don’t stop any medicine unless your doctor tells you to.
• Mention any allergies, including to numbing medicine or latex.
• Wear a two-piece outfit, since you’ll undress from the waist up.
• Skip deodorant, powder and lotion on your chest and underarms if you are having imaging the same day.
• Bring a supportive bra to wear afterward.

What happens during fine-needle aspiration

You lie on your back or slightly on your side. The skin is cleaned. Because the needle is so thin, numbing medicine isn’t always needed, but some doctors use it.

The doctor holds the lump steady with one hand or uses an ultrasound picture to guide the needle to the right spot. The needle goes into the lump, and a syringe pulls back to draw out fluid or cells. The doctor may move the needle back and forth a little, or make two or three passes, to collect enough. Each pass takes a few seconds, and the whole test usually takes 10 to 20 minutes.

Cyst fluid is often yellow, green or brown. If the lump was a cyst, it usually flattens as the fluid comes out. Afterward, the doctor presses on the spot for a few minutes and puts on a small bandage.

Afterward

Most people go back to their usual day right away and can drive themselves home. The area may feel sore or look bruised for a few days. A cold pack, a supportive bra and acetaminophen can help. Ask your doctor before taking ibuprofen or aspirin if you’re prone to bruising.

Possible risks

• Bruising, soreness and minor bleeding
• Feeling lightheaded or fainting during the test
• Infection, which is rare
• A sample that doesn’t have enough cells to give an answer, meaning you may need another test

Serious problems are very uncommon.

Your results

If the lump was a cyst

If the fluid looks normal and the lump goes away completely, no more testing is usually needed. The fluid is often thrown away rather than sent to the lab. If the fluid is bloody, or a lump is still there afterward, the fluid is tested and you’ll likely need more imaging or a biopsy.

If the lump was solid

A doctor who specializes in reading cells under a microscope (a pathologist) reports the result as one of these:

• Benign. No cancer, for example a fibroadenoma, a common harmless lump.
• Unclear or atypical. The cells look a bit unusual, so a core or surgical biopsy is needed.
• Suspicious or cancer. You’ll have more tests and meet with a breast specialist to plan treatment.
• Not enough cells. The test may need to be repeated, or a core biopsy done.

A benign result should match what the exam and imaging show. If it doesn’t, your doctor will recommend more testing. You may also be asked to come back for a follow-up ultrasound in a few months.

When to call your doctor

• Swelling, redness or warmth that is getting worse
• Fever or chills
• Bleeding that soaks through the bandage
• Pain that keeps getting worse
• The lump comes back, or you find a new one
• You haven’t heard your results when expected

Common questions about fine-needle aspiration

What does aspiration mean in medical terms?

Aspiration has two medical meanings. In a procedure like this one, it means using suction through a needle to draw out fluid, cells or air. It also describes accidentally breathing food, liquid or saliva into the lungs, which can cause pneumonia. The two meanings aren’t related.

Does a breast fine-needle aspiration hurt?

Most people feel a quick pinch and some pressure, similar to having blood drawn. The needle used is thinner than most needles for blood tests. Soreness afterward is usually mild and gone within a few days. Tell your doctor if you’re anxious; numbing medicine can be used.

Can a breast cyst come back after it is drained?

Yes. Cysts sometimes refill, and new ones can form, especially before menopause. A cyst that comes back can be drained again if it is painful. Your doctor may suggest imaging or a biopsy if a cyst keeps returning in the same spot or the fluid is bloody.

Is fine-needle aspiration accurate?

For cysts, FNA is very reliable, since the lump disappears when the fluid is removed. For solid lumps, it is less complete than a core needle biopsy and sometimes misses or can’t classify a cancer. That is why doctors compare the result with your imaging and order more tests if anything doesn’t fit.

Questions to ask your doctor

• Do you think this lump is a cyst or solid?
• Why are you recommending FNA instead of a core biopsy?
• Will you use ultrasound to guide the needle?
• When and how will I get my results?
• What follow-up will I need if the result is benign?

Learn more

• Breast biopsy (MedlinePlus, U.S. National Library of Medicine)
• Benign and precancerous breast conditions (National Cancer Institute)

This guide is general information and doesn’t replace advice from your own doctor. Last updated October 2026.