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What is a breast biopsy?

A breast biopsy is a procedure to remove a sample of cells or tissue from a suspicious area in the breast for examination under a microscope. A biopsy is the only conclusive way to diagnose breast cancer, because even though lumps or abnormalities in the breast are often detected by physical examination—or by mammography or another imaging study—it is not always possible to tell from these kinds of exams whether a growth is benign or cancerous.

The kind of biopsy your doctor recommends will depend on several factors, such as the appearance of the breast change and how suspicious it looks; its size and location; your medical history, including any other conditions you have; and your preferences. In many cases, the doctor will use imaging during biopsy to guide his or her instruments to the area of abnormal cell growth. Image-guided biopsy can be done using a variety of imaging technologies, such as ultrasound, magnetic resonance imaging (MRI) and mammography. When mammography is used to guide a biopsy, the procedure is called stereotactic breast biopsy.

No matter what kind of biopsy you have, the tissue samples will be sent to a lab to be examined by a pathologist, a doctor who specializes in the study of samples of body tissue. It typically takes several days to get the results of this examination.

Needing a biopsy does not necessarily mean you have breast cancer. In fact, in the United States, only about 20% of women who have a biopsy turn out to have cancer.

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Why it's done

A breast biopsy may be recommended if you or your doctor notice a change in your breast—for instance, a lump or thickening, or a dimpling of the skin (it may look like an orange peel). Breast or nipple pain, nipple retraction, or nipple discharge are other signs that might prompt a doctor to advise testing. Even if you haven’t noticed any breast changes, a biopsy may be recommended if a mammogram, ultrasound or MRI shows something suspicious.

Our approach

When an abnormality is identified in the breast, a biopsy is a critical tool in investigating—and in many cases, imaging can make the biopsy process easier, safer and more effective. When it comes to breast biopsies, the radiologists at Northwell Health Imaging are the power behind the procedure. Every breast biopsy is performed by a fellowship-trained interventional radiologist whose skills have been honed by specialized training and thousands of hours of experience.

If you need additional care, your radiologist will work side by side with the rest of your care team, collaborating closely to answer your questions and help guide your care.

Northwell Health Imaging offers the largest group of fellowship-trained and subspecialized radiologists on Long Island, as well as access to all the resources and clinical expertise of New York state’s largest health system. Whether you are here for screening, diagnostic or treatment imaging services, each of our practitioners is committed to providing a caring, comfortable environment and a positive, productive experience.

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Risk factors

All biopsies can cause bruising, bleeding and swelling. There is also the chance of infection, as in any procedure in which the skin is penetrated. A biopsy may also alter the appearance of your breast, depending on how much tissue is removed.

If you have a stereotactic breast biopsy—in which the physician uses mammography to help precisely locate the tissue to be sampled—you will be exposed to a small amount of radiation, slightly more than the amount of background radiation normally present in the soil and air. If there is a possibility that you might be pregnant, let your technologist know. Stereotactic biopsy is safe in pregnancy and does not cause any fetal risk, but we can use lead shielding as an added precaution.

When your breast biopsy results are received from the pathologist, the radiologist will make recommendations regarding followup care. Core needle biopsy has been proven to be an accurate and reliable way to evaluate breast masses, and has replaced surgical biopsy for most types of breast abnormalities. However, uncommonly, a core needle biopsy result may be a “false positive”—meaning that the results don’t show cancer when in fact a cancer is present. For that reason, the radiologist will typically recommend at least one followup imaging examination after biopsy, even with a benign result, to make sure that there are no unexpected developments.


There are several ways to perform a breast biopsy:

  • Fine needle aspiration (FNA)—In a FNA biopsy, the doctor uses a very fine needle and syringe to extract (aspirate) a small amount of fluid or tissue from the area being investigated. The needle used in FNA is thinner than one used for blood tests. In some cases, the doctor may use imaging during the biopsy, such as ultrasound or mammography, to help guide the placement of the needle.
  • Core needle biopsy—The doctor uses a device with a larger, hollow needle to extract a cylinder (core) of tissue. In most cases, the doctor will insert the needle several times in order to take a number of samples. In some cases, the doctor may use imaging during the biopsy, such as ultrasound or mammography, to help guide the placement of the needle.
  • Vacuum-assisted biopsy—This approach is a type of core needle biopsy, but uses a probe that needs to be inserted just once. It is able to extract more tissue than a core needle biopsy does.
  • Surgical biopsy—The physician makes an incision into the breast and takes either part of the tumor (“incisional biopsy”) or the entire mass (“excisional biopsy”). If the breast mass can’t be felt, the physician may use a mammogram, ultrasound or MRI before the surgery to place a thin wire in the mass as a guide to the area to be removed.

What to expect

Both FNA and core needle breast biopsies are generally done as outpatient procedures.

For a FNA, your doctor may or may not give you an injection to numb the area—the needle used for the breast biopsy is so thin that the anesthetic injection might hurt more than the biopsy itself. You’ll lie on your back for the FNA as the doctor guides the needle into the lump. Imaging may be used to help direct the placement of the needle. Once the needle is in the right spot, the doctor will extract a small amount of tissue and/or fluid. This process may be repeated several times, with each collection taking just a few seconds. Afterward, a sterile dressing or bandage will be used to cover the area.

If you are having a core needle biopsy, a radiologist will use a hollow needle to extract small cylindrical samples (cores) of breast tissue from the suspicious area. You may be given local anesthesia, which numbs your breast but doesn’t put you to sleep. A small incision will be made in the breast and the needle will be inserted; a spring-loaded mechanism may move the needle in and out of the tissue quickly. Your doctor may use imaging such as ultrasound, MRI or mammogram to guide the position of the needle.

During a FNA or core needle breast biopsy, the physician may place a tiny stainless steel marker or clip at the biopsy site. If the laboratory analysis of the biopsied cells shows that surgery is needed, the clip will help the surgeon locate the precise area more easily.

How to prepare

Some medications (both prescription and over-the-counter) and supplements can raise the risk of bleeding during or after the biopsy, so it’s important to tell your doctor about all medications and supplements you take.

You should also tell the doctor if you have any allergies, and about recent illnesses or other medical conditions.

Tell your doctor if there is a possibility that you might be pregnant.

If your biopsy will be guided by MRI, tell your doctor if you have if you have medical or electronic devices in your body.

On the day of the procedure, you should not wear deodorant, powder, lotion or perfume under your arms or on your chest. Wear a bra to the appointment; it can provide support after the procedure and may also be used to hold a cold pack in place.


After FNA or a core breast biopsy, only bandages and an ice pack to reduce swelling are needed over the biopsy site.

Our nurses will give you instructions after your biopsy. The instructions will include avoiding heavy lifting on the day of the procedure, keeping the area dry for 24 hours, and using ice and acetaminophen (Tylenol, for instance) for pain. We will give you an ice pack. You should not take aspirin or NSAIDS (such as Motrin) for biopsy-related pain, but you can continue to take these medications if you need them for other medical reasons.


Tissue or fluid extracted during a breast biopsy is examined by a pathologist, a doctor specially trained to identify diseases and conditions by studying cells and tissues. The pathology results are typically available within a week, sometimes sooner. Our nurse or radiologist will call you with the results and followup recommendations, and will also forward the results to your doctor.

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