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Bone Marrow Tests

What Are Bone Marrow Tests?

Bone marrow is a soft, spongy tissue found in the center of most bones. Bone marrow makes different types of blood cells, including:

  • Red blood cells (also called erythrocytes), which carry oxygen from your lungs to every cell in your body
  • White blood cells (also called leukocytes), which help you fight infections
  • Platelets, which help with blood clotting

Bone marrow tests check to see if your bone marrow is working correctly and making normal amounts of blood cells. The tests can help diagnose and monitor bone marrow disorders, blood disorders, and certain types of cancer.

There are two types of procedures used to collect bone marrow samples for testing:

  • Bone marrow aspiration removes a small amount of bone marrow fluid and cells
  • Bone marrow biopsy removes a small piece of bone and bone marrow

Bone marrow aspiration and bone marrow biopsy are usually done at the same time.

Other names: bone marrow examination

What are they used for?

Bone marrow tests are used to:

  • Find out the cause of problems with red blood cells, white blood cells, or platelets
  • Diagnose and monitor blood disorders, such as:
  • Diagnose bone marrow disorders
  • Diagnose and monitor treatment for certain types of cancers, including leukemia, multiple myeloma, and lymphoma
  • Diagnose the cause of an unexplained fever, which could be from an infection in the bone marrow

Why do I need a bone marrow test?

Your health care provider may order a bone marrow aspiration and a bone marrow biopsy if other blood tests show your levels of red blood cells, white blood cells, or platelets are not normal.

Too many or too few blood cells may mean you have a medical condition, such as cancer that starts in your blood or bone marrow. If you are being treated for another type of cancer, these tests can find out if the cancer has spread to your bone marrow.

Bone marrow tests may also be used to see how well cancer treatment is working.

What happens during a bone marrow test?

Bone marrow aspiration and bone marrow biopsy procedures are usually done at the same time. A health care provider will collect the marrow samples for testing. Usually, the samples can be collected in about ten minutes.

Before the procedure, you may be asked to put on a hospital gown. Your blood pressure, heart rate, and temperature will be checked.

You may choose to have a mild sedative, which is medicine to help you relax. You may also have the choice to use stronger medicine that will make you sleep. Your provider can help you decide which option is best for you.

During the procedure:

  • You'll lie down on your side or your stomach, depending on which bone will be used to get the samples. Most bone marrow samples are taken from the back of the hip bone, called the iliac crest. But other bones may be used.
  • An area of skin over the bone will be cleaned with an antiseptic.
  • You will get an injection (shot) of medicine to numb the skin and the bone underneath. It may sting.
  • When the area is numb, the provider will make a very small incision (cut) in your skin and insert a hollow needle. You will need to lie very still during the procedure:
    • The bone marrow aspiration is usually done first. The provider will push the needle into the bone and use a syringe attached to the needle to pull out bone marrow fluid and cells. You may feel a brief, sharp pain. The aspiration takes only a few minutes.
    • The bone marrow biopsy uses a special hollow biopsy needle inserted through the same skin opening. The provider will twist the needle into the bone to take out a small piece, or core, of bone marrow tissue. You may feel some pressure or brief pain while the sample is being taken.
  • After the test, the health care provider will cover your skin with a bandage.
  • If you didn't use medicine to relax or sleep, you'll usually need to stay lying down for about 15 minutes to make sure that the bleeding has stopped. Afterwards, you can do your usual activities as soon as you are able. If you used medicine to relax or sleep, you'll need to stay longer before you can go home. You may also need to rest the next day.

Will I need to do anything to prepare for the test?

Your provider will tell you whether you need to fast (not eat or drink) for a few hours before the procedure.

Plan to have someone take you home after the test, because you may be drowsy if you are given medicine to help you relax or sleep during the procedure.

You'll receive instructions for how to prepare, but be sure to ask your provider any questions you have about the procedure.

Are there any risks to the test?

After a bone marrow aspiration and bone marrow biopsy you may feel stiff or sore where the sample was taken. This usually goes away in a few days.

Your provider may recommend or prescribe a pain reliever to help. Don't take any pain medicine your provider hasn't approved. Certain pain relievers, such as aspirin, could increase your risk of bleeding.

Serious symptoms are very rare, but may include:

  • Increased pain or discomfort where the sample was taken
  • Redness, swelling, bleeding, or other fluids leaking from at the site
  • Fever

If you have any of these symptoms, call your provider.

What do the results mean?

It may take several days or even weeks to get your bone marrow test results. Your provider may have ordered many different types of tests on your marrow sample, so the results often include a lot of complex information. Your provider can explain what your results mean.

In certain cases, if your test results are not normal, you may need to have more tests to confirm a diagnosis or to decide which treatment would be best.

If you have cancer that affects your bones and marrow, your test results may provide information about your cancer stage, which is how much cancer you have in your body and how fast it may be growing.

If you are already being treated for cancer, your test results may show:

  • How well your treatment is working
  • Whether your treatment is affecting your bone marrow

Learn more about laboratory tests, reference ranges, and understanding results.


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The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.