What Is a Bone Marrow Biopsy?

What to expect when undergoing this test

A bone marrow biopsy is a procedure that obtains a sample of bone tissue marrow to evaluate the different types of blood cells, as well as the structure of the bone marrow. It can be used to diagnose diseases of the blood and bone marrow such as leukemias and lymphomas, figure out the cause of unexplained anemia or bleeding, and diagnose some genetic conditions. The most common site for a bone marrow biopsy is the large pelvic bone near the hip (posterior iliac crest), but a sample may also be taken from the sternum (breastbone), or, in infants, the shin bone (tibia).

A bone marrow examination actually consists of two separate tests that are often done at the same time; a bone marrow aspiration that obtains a sample of the liquid portion of the bone marrow, and a bone marrow biopsy that obtains a sample of the solid material. In addition to providing information about the types and proportions of blood cells as well as bone marrow structure, special tests on the sample obtained can be used to further identify and subtype any abnormal cells.

bone marrow biopsy
 Illustration by Cindy Chung, Verywell

Purpose of Test

Bone marrow is the spongy material found inside of long bones, the pelvis, and the breastbone that produces all of the types of blood cells. There are a number of different reasons why a healthcare provider may recommend a biopsy, and they all relate to the bounty of cellular material the bone marrow contains.

What Bone Marrow Contains

Pluripotential stem cells are the origin of all of the blood cells that develop through a process called hematopoiesis. These blood cells, which are born in bone marrow, have different functions:

  • White blood cells: To fight infections with bacteria, viruses, and parasites, as well as cancer cells
  • Red blood cells: To carry oxygen to all of the cells in the body
  • Platelets: To aid in blood clotting

Stem cells initially divide into two different groups:

Bone marrow also contains connective tissue and the materials that are important to the manufacturing of blood cells, such as iron, vitamin B12, and folic acid.


A bone marrow biopsy may be done for the following reasons:

  • To uncover a reason for an abnormal level (high or low) of red blood cells (anemia or polycythemia), white blood cells (leukopenia or leukocytosis), or platelets (thrombocytopenia or thrombocytosis). While a complete blood count can detect abnormal levels of blood cells, the results do not explain why the levels are high or low.
  • To evaluate a fever of unknown origin (a fever that persists without any obvious cause)
  • To investigate abnormal bleeding or clotting
  • To diagnose, further evaluate, or subtype known cancers that begin in the bone marrow, such as leukemias and lymphomas, when there are not enough circulating cancer cells to make the diagnosis otherwise
  • To see if some cancers have spread to the bone marrow
  • To follow the progress of a cancer or bone marrow disease, either to decide when to initiate treatment or to monitor the results of treatment
  • To evaluate iron overload conditions and monitor iron levels
  • To identify stem cell disorders and some rare genetic syndromes

By looking at a sample of bone marrow, healthcare providers can determine if too many of one type of blood cell are being made, or if the bone marrow contains tumor or fibrosis that crowds out the normal production of these cells. Findings can help zero in on diagnoses such as:


Since the contents of the bone marrow may vary in different regions, an aspiration and biopsy done in one region may not be representative of the whole or may miss focal areas of bone marrow involvement with tumor or other conditions. The technique is also dependent on the skill of the healthcare provider performing the procedure and the quality of the samples obtained.

Since bleeding is the most common side effect of the procedure, it may be challenging when a person has a low platelet count.

Comparison to Other Tests

Unlike a complete blood count (CBC) and peripheral smear that looks at mature blood cells in the circulation (peripheral blood), a bone marrow biopsy gives important information about blood cells in all stages of development. It can also provide evidence of bone marrow disease (such as fibrosis) that cannot be detected on peripheral blood.

Risks and Contraindications

As with any medical test, there are potential risks to a bone marrow biopsy, as well as reasons why the test may not be recommended.

Potential Risks

The most common side effect of a bone marrow aspiration and biopsy is bleeding. This is uncommon overall (less than 1 percent) but is more likely to occur if a person's platelet count is low. In this case, however, the benefits of a diagnosis may still outweigh any potential risk.

Infection (due to the opening in the skin where the needle enters) may also occur, especially in people who are at a greater risk of infection due to a reduced number of white blood cells. Persistent pain after the procedure may also occur for some people. These risks can be reduced by checking a complete blood count prior to the procedure.

When a bone marrow aspiration is performed on the breastbone (sternum) there is a small risk of damage to nearby structures due to the close proximity of the heart and lungs.

There is also a small risk of side effects or an allergic reaction to the medications given to make you drowsy (or heavier sedation in children) or to the local anesthetic used to numb the site where the needle is placed.


In people who have a very low platelet count, the procedure may need to be delayed, or platelet transfusions may be given prior to the biopsy. For those who have a very low white blood cell count, the procedure may also be delayed, or medications may be given to increase counts before the test is done.

Before the Test

When your healthcare provider recommends a bone marrow biopsy, she will discuss the procedure and any potential risks. She will want to know about any medications, over-the-counter remedies, or supplements you are taking, and will ask you whether you or anyone in your family has a history of bleeding disorders. She will also ask you about any allergies, including an allergy to local anesthetics or to latex, and whether you are pregnant or if there is a chance you are pregnant. During this visit, it's important to ask any questions you have and talk about any anxiety you have about the procedure.


While the amount of time it takes to perform a bone marrow aspiration and biopsy is only around 10 minutes, you should plan on dedicating at least an hour or two to the procedure. This will include time for a nurse to provide you with medications to relax you if needed, time to clean and anesthetize the area, and time after the procedure to make sure you are ready to return home.


A bone marrow test is usually done as an outpatient procedure at a hematologist/oncologist's office, but may also be done at a hospital.

What to Wear

Most of the time, a person will be asked to change into a gown before the procedure. It's a good idea to dress in loose clothing to reduce discomfort at the site of the procedure after it is done.

Food and Drink

Healthcare providers vary in their recommendations, but some ask that you not eat beginning at midnight the night prior to the procedure. Drinking clear liquids such as water is usually alright, but talk to your healthcare provider about her recommendations.


You may be asked to stop some medications before your bone marrow test, such as blood thinners, aspirin, or nonsteroidal anti-inflammatory drugs like Advil (ibuprofen), but talk to your healthcare provider. Sometimes the risk of stopping blood thinners is greater than the risk of bleeding due to the procedure. Keep in mind that some medications may need to be discontinued a week or more before the test. Some vitamins and dietary supplements can also increase the risk of bleeding, and it's important to talk to your healthcare provider about any you use before the test.

Cost and Health Insurance

Most health insurance companies will cover a bone marrow aspiration and biopsy, but in some cases, prior authorization may be required. You will likely be billed separately for different aspects of the test. The practitioner performing the test will bill for the procedure, a test that currently runs between $1,700 and $2,800, depending on the facility and area where you live. The pathologist usually bills separately for any tests run on the sample. This figure can vary significantly depending on whether the sample is only viewed under the microscope or specialized molecular tests are done.

Procedures done at a hospital are usually costlier than those done in a clinic.

For those who are uninsured, there are several options, and it's important to talk to a social worker at your clinic or hospital if you are concerned about the cost. Some clinics offer discounts for those who do not have insurance and set up a payment plan ahead of time. If your healthcare provider is concerned about a leukemia, lymphoma, or the spread of other cancers to the bone marrow, there are a number of ways to find financial assistance if you have cancer.

What to Bring

On the day of your appointment, you should bring your health insurance card and any paperwork you were asked to fill out. It's always a good idea to pack a book or magazine in the event there is a delay in the start of the procedure.

Other Considerations

If you aren't given sedation, you may be able to drive yourself to the appointment. That said, the biopsy site will likely be sore, and you will probably be more comfortable as a passenger in the car than as the driver. Having a companion with you can help you pass the time and provide support during an anxious time.

During the Test

During your bone marrow test, you will be attended to by the hematologist/oncologist (or other trained specialists) performing the procedure and a nurse. A laboratory technician may also be present to assist in collecting the sample, making blood smears, and delivering these to the laboratory.


At the start of the test, you will be asked to sign a consent form indicating that you understand the purpose of the test and the potential risks. If you will be receiving IV sedation, an IV will be placed. Oral sedation may be given for adults who are anxious about the procedure. Your vital signs (heart rate, blood pressure, and temperature) will be taken, and you will again be asked whether you have any concerns.

Throughout the Test

In the procedure room, you will be asked to lie on your side, back, or abdomen, depending on the site of the biopsy:

  • A hip biopsy is done in two parts, the aspiration and then the biopsy. The back of the hip (posterior iliac crest) is used more commonly than the front. This is by far the most common site used for a bone marrow examination.
  • A breastbone (sternum) biopsy is done only in adults and children over the age of 12, and includes only an aspiration.
  • A tibia (shin) biopsy is done only in infants less than one year of age, as it provides insufficient cells in adults.

The area where the biopsy will be performed will be cleansed with a disinfectant and the area draped with sterile towels. The surface of the skin will then be numbed locally with a lidocaine injection, which will cause you to feel a sting.

After making a small incision in the skin, a hollow needle is inserted. You will feel pressure as it enters your skin, then a sharp, momentary sting when the needle enters the bone. The needle has an internal rod called a bone trocar that will then be removed.

The aspiration is done first and is usually the most painful part of the procedure. The healthcare provider attaches a syringe to the needle after removing the trocar and withdraws fluid. This often causes a deep ache, but fortunately, only takes a few seconds. If the sample does not have enough fluid, another sample may need to be taken from another site.

With a bone marrow biopsy, a thicker needle is inserted into the bone with a twisting motion to take a core, solid sample of the bone marrow. The biopsy often causes sharp pain for a few seconds while the sample is being taken.


When the procedure is done, the needle is removed and pressure is applied to the area to stop any bleeding. The area is then covered with an antiseptic dressing. You will be asked to lie down for 10 to 15 minutes before leaving. You may note some soreness as the local anesthetic wears off.

After the Test

You should keep the biopsy site dry and covered for two days and avoid showering, baths, or swimming during this time. You may give yourself a sponge bath or wash your hair in the sink or tub as long as the biopsy site doesn't get wet. Your healthcare provider may instruct you to inspect and change the dressing, but this can vary.

You will be able to resume your regular diet as soon as the test is completed, as well as many of your activities. It's important, however, to avoid excessive activity or heavy lifting for the first few days after the biopsy. You will be able to take most of your medications as soon as your bone marrow examination has been completed, but should talk to your healthcare provider about when to resume taking any blood thinners and medications such as aspirin or anti-inflammatories.

Managing Side Effects

You may feel achy in the region of your biopsy for a few days and may be advised to use Tylenol (acetaminophen) or prescription pain medications to treat any discomfort. Most often, people are advised to avoid aspirin or nonsteroidal anti-inflammatory drugs such as Advil (ibuprofen) or Aleve (naproxen), as these can increase bleeding.

When to Call Your Healthcare Provider

It's important to call your healthcare provider if you have any bleeding from the site that does not stop with pressure on the wound; if you develop signs of infection, such as a fever, redness, swelling, or discharge from the biopsy site; or if you have significant pain that is not going away or getting worse.

Interpreting Results

The samples from your bone marrow will be reviewed under a microscope in the pathology lab. Some results may be available shortly after your biopsy, but others can take longer. Those of chromosome studies, for example, may take two weeks or more to come back.

More than a dozen cell types will be evaluated and results will be compared to reference ranges, which vary widely and can differ depending on age. Comparing your results to these ranges, as a patient, is not entirely useful, as the set of results as a whole is what's telling. A pathologist and your healthcare provider will be able to shed proper light on this for you.

Bone Marrow Aspiration Results

Evaluation of the liquid bone marrow sample can reveal:

  • The number of each type of blood cell
  • The proportion of each type of blood cell relative to other blood cells in the marrow
  • The myeloid/erythroid ration (ME ratio): The number of cells that are precursors of white blood cells compared with the number of cells that are precursors to red blood cells
  • The maturity of cells: For example, blasts may make up to 20 percent to 30 percent of the type of white blood cells in cases of acute lymphocytic leukemia and acute myelocytic leukemia. While this may be diagnostic of acute leukemia, further testing will be needed to determine the subtype of the leukemia.
  • Whether abnormal cells such as leukemia cells or tumor cells are present

Bone Marrow Biopsy Results

The bone marrow biopsy also looks at the number and types of blood cells, but also gives important information about the structure of the bone marrow. Results include:

  • The numbers and types of white blood cells, red blood cells, and platelets at all stages of development (to determine if there are adequate numbers)
  • Cellularity: The number of blood cells relative to other components of bone marrow such as fat (this can vary at different ages)
  • Infiltrates: Whether anything abnormal is present in the bone marrow, such as cancer or an infection
  • Changes to the bone marrow stroma, such as fibrosis
  • Changes to the bone, such as osteoporosis

Special Tests

In addition to the samples being examined, special tests may be done on them depending on the possible diagnosis. These may include:

  • Tests to diagnose and stage leukemia, lymphoma, and myeloma, such as cytochemistry (flow cytometry and immunophenotyping), chromosomal studies, and molecular testing: While the results above may be diagnostic for blood-related cancers, these special tests are often needed to determine subtypes and molecular characteristics of the cancer that are important in choosing the best treatment options.
  • Cultures and stains to look for certain viruses, bacteria, and fungi
  • Stains to look for iron overload


Follow-up after a bone marrow test will depend on the diagnosis and treatments that are recommended. Depending on your results, consider whether a second opinion might be appropriate before beginning any treatment.

A Word From Verywell

Scheduling your bone marrow biopsy can be very anxiety-provoking, as you consider both the discomfort of the procedure and the possible diagnoses that could be found. Worry can persist after the procedure as well, since some of the specialized study results can take weeks to be delivered. Understanding what the test will be like, asking questions about anything you don't understand, and educating yourself about any abnormalities found can help you feel more in control of your care and empowered as you make decisions going forward.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Lab Tests Online. Bone Marrow Aspiration and Biopsy. Updated April 29, 2018.

  2. American Society of Clinical Oncology. Bone Marrow Aspiration and Biopsy. Updated August 2018.

  3. U.S. National Library of Medicine. Bone marrow biopsy. Updated April 2, 2018.

  4. UChicago Medicine Medical Laboratories. Bone Marrow Differential.