Core Needle Biopsy: About This Test

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What is a core needle biopsy?

A core needle biopsy is a test to take samples of tissue using a needle with a special tip. The samples are looked at under a microscope to check for changes in the cells.

Why is this test done?

A core needle biopsy is most often done to check a lump found during an exam. It may also be done when an area of concern is found on a mammogram, ultrasound, or other imaging.

How do you prepare for the test?

If you take aspirin or some other blood thinner, ask your doctor if you should stop taking it before your test. Make sure that you understand exactly what your doctor wants you to do. These medicines increase the risk of bleeding.

How is it done?

  • Depending on what part of your body is being tested, you may sit in a chair or lie on a table. After you are positioned, the doctor or nurse will clean and numb the area where the biopsy will be done. Or you may have intravenous (IV) sedation or general anesthesia, which will make you sleep.
  • When the area where the doctor will do the biopsy is numb, a small cut (incision) is made in the skin.
  • The doctor may use ultrasound, an X-ray, a CT scan, or an MRI to help guide the placement of the biopsy needle.
  • The doctor will take several samples. This may be done with the needle or with a probe that uses a gentle vacuum to remove the samples.
  • A marker may be placed in the biopsy site. You won't be able to feel or see this marker after it is placed. But the marker will be visible in future imaging tests, such as mammograms, ultrasounds, and MRIs. This will help the doctor find the area later.
  • The needle is removed, and pressure may be put on the needle site to stop any bleeding.
  • A bandage may be put on the needle site.

How does it feel?

You may feel only a quick sting from the needle if you're given a shot to numb the biopsy area. You may feel some pressure as the biopsy needle removes samples. But if you have general anesthesia, you won't feel anything during the procedure.

How long does it take?

The test may take 15 minutes to an hour. But it may take longer if general anesthesia was used.

What happens after the test?

  • You'll be told how long it may take to get your results back.
  • You will probably be able to go home right away. But this will depend on the location of the biopsy and if general anesthesia was used.
  • After the doctor looks at the biopsy sample, their office will let you know the results.
  • If the test results aren't clear, you may have another biopsy or test.

How can you care for yourself at home?

  • Your doctor will tell you when you can resume your normal activities.
  • The site may be tender for 2 or 3 days. You may also have some bruising, swelling, or slight bleeding.
    • You can use an ice pack. Put ice or a cold pack on the area for 10 to 20 minutes at a time. Put a thin cloth between the ice and your skin.
    • Ask your doctor if you can take an over-the-counter pain medicine, such as acetaminophen (Tylenol), ibuprofen (Advil, Motrin), or naproxen (Aleve). Be safe with medicines. Read and follow all instructions on the label.

When should you call for help?

Call 911 anytime you think you may need emergency care. For example, call if:

  • You passed out (lost consciousness).
  • You have severe trouble breathing.
  • You have severe pain in your belly or chest.

Call your doctor now or seek medical care if:

  • You have new or worse pain or swelling.
  • Bright red blood has soaked through the bandage over the biopsy site.
  • You cough up blood.
  • You are sick to your stomach or cannot keep fluids down.
  • You are dizzy or lightheaded, or you feel like you may faint.
  • You have signs of infection, such as:
    • Increased pain, swelling, warmth or redness.
    • Red streaks leading from the puncture site.
    • Pus draining from the puncture site.
    • A fever.

Watch closely for changes in your health, and be sure to contact your doctor if you have any problems.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. Ask your doctor when you can expect to have your test results.




The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.