At a Glance
Why Get Tested?
To evaluate the type, quantity, and maturity levels of the blood cells present in the marrow; to evaluate the fibrous structure of the marrow; and sometimes to collect a sample of marrow for more specific testing
When to Get Tested?
When a patient is anemic without an obvious cause and/or has a condition or cancer that may be affecting blood cell production; sometimes when a doctor is investigating a fever of unknown origin, especially when the patient is immuno-compromised
A bone marrow sample collected primarily from the hip bone (pelvis); sometimes collected from the sternum in adults or the tibia (shin bone) in infants
Test Preparation Needed?
The Test Sample
What is being tested?
Bone marrow aspiration and biopsy are procedures used to collect and evaluate bone marrow. Bone marrow is a soft fatty tissue found inside the body’s larger bones. It has a honeycomb or sponge-like structure, consisting of a fibrous network that is filled with liquid. The liquid contains stem cells, blood cells in various stages of maturation, and “raw materials” such as iron, vitamin B12, and folate that are required for cell production. A bone marrow aspirate collects a liquid sample of cells that can be studied individually. A biopsy collects a cylindrical core sample that preserves the marrow’s structure. The biopsy shows the relationships of bone marrow cells to one another and the overall cellularity – the ratio of marrow cells to fat and other constituents present in the sample.
Red blood cells (RBCs), platelets, and five different types of white blood cells (WBCs) are produced in the marrow as needed, with the number and type of cell being produced at any one time based on the use of cells, loss, and a continual replacement of old cells. For instance, RBCs, which carry oxygen throughout the body, have a lifespan of about 120 days. The marrow paces RBC production at such a rate as to replace old RBCs that are taken out of circulation and maintain a relatively constant number in the blood. The marrow increases the rate of RBC production whenever the person’s number of RBCs decreases, due to such things as bleeding or hemolysis. The increased rate of production continues until there is a sufficient number of RBCs in the blood stream or until marrow production capacity is reached. If the need approaches this capacity, then an increased number of reticulocytes (immature RBCs) will be released into circulation as the marrow tries to keep up. If the need exceeds capacity, then the number of RBCs in the blood stream will decrease and the patient will become increasingly anemic, with symptoms such as pallor, fatigue, and shortness of breath due to decreased oxygen in the blood.
There are a variety of bone marrow disorders, cancers such as leukemia, vitamin and mineral deficiencies, inherited conditions, and diseases such as aplastic anemia that can affect the marrow’s ability to produce an adequate number of each of the different blood cell types and release them into circulation. These diseases may affect the overall number of cells produced, the proportion of cells produced, and/or the function of the cells. Some bone marrow disorders may lead to a deficiency of one or more cell types while others result in excess production of a specific type or of a specific clone of a cell - a single cell that reproduces without regulation.
Leukemia, for example, is a cancer of the blood cells. It results in the excessive production of one WBC type at the expense of other cell types and can lead to the release of large quantities of abnormal immature WBCs into the blood stream. These WBCs do not fight infection as other WBCs do and they leave the patient more vulnerable to illness. When leukemic WBCs crowd out RBC production in the bone marrow, the patient becomes anemic; when they decrease the number of platelets produced, they leave the patient vulnerable to excessive bruising and bleeding. Other conditions, such as vitamin B and folate or iron deficiency, lead to the creation of large or small or abnormally shaped RBCs and result in specific types of anemia. Another disorder, myelofibrosis, is characterized by the overgrowth of the fibrous network found in the marrow, compressing cells and leading to changes in red cell shape and changes in the cell counts.
Bone marrow aspiration and/or biopsy as a “test” includes both the collection of marrow samples and the evaluation of it under the microscope. Specialists, a pathologist and/or hematologist, microscopically examine slides containing stained smears of marrow samples – the fibrous network and fluid from a biopsy or the fluid from an aspiration. The number, size, and shape of each of the cell types present are examined, as are the proportions of mature and immature cells. If leukemia is present, or another cancer has spread into the marrow, it can be diagnosed through this examination, and the type and severity of the disease (the stage) can be established.
Depending on what condition(s) the doctor suspects, additional tests can be performed on the marrow sample. It may be cultured to look for viral, bacterial, or fungal infections that can cause a “fever of unknown origin.” In the case of leukemia, tests to determine the type of leukemia may be done. These include special stains or the determination of antigenic markers (immunophenotype) to show just what type of leukemia is present. Special stains may also be used to look for things such as excess iron storage in the marrow, and tests are sometimes ordered to detect chromosomal abnormalities.
How is the sample collected for testing?
The bone marrow aspiration and/or biopsy procedure is performed by a doctor or other trained specialist. Both types of samples may be collected from the hip bone. Marrow aspirations are sometimes collected from the sternum (breastbone) of adults. In infants, samples may be collected from the tibia (shin bone).
The most common collection site is the iliac crest (top ridge) of the back of the hip bone. Before the procedure, the patient’s blood pressure, heart rate, and temperature are measured and evaluated to make sure that they are within normal limits, and some patients are given a mild sedative. The patient is then asked to lie down on his stomach or side for the collection, and his lower body is draped with cloths so that only the area surrounding the site is exposed.
The site is cleaned with an antiseptic such as iodine and injected with a local anesthetic. When the site has numbed, the doctor inserts a needle through the skin and into the bone. For an aspiration, the doctor attaches a syringe to the needle and pulls back on the plunger. This creates vacuum pressure and pulls a small amount of marrow into the syringe. For a bone marrow biopsy, the doctor uses a special needle that allows the collection of a core (a cylindrical sample) of marrow.
Even though the patient’s skin has been numbed, the patient may feel brief but uncomfortable pulling and/or pushing pressure sensations during these procedures. After the needle has been withdrawn, a sterile bandage is placed over the site and pressure is applied. The patient is then usually instructed to lie quietly until his blood pressure, heart rate, and temperature are normal, and then to keep the collection site dry and covered for about 48 hours.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 183-188.
Corinne Goldberg, C. et. al (2008 April 7, Updated). Bone Marrow Aspiration and Biopsy. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/207575-overview through http://emedicine.medscape.com. Accessed on 1/4/09.
Dugdale, D., Updated (2008 July 11, Updated). Bone marrow aspiration. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003658.htm. Accessed on 1/4/09.
Dugdale, D., Updated (2008 July 11, Updated). Bone marrow biopsy. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003934.htm. Accessed on 1/4/09.
Mayo Clinic Staff (2007 November 15). Bone marrow biopsy and aspiration. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/bone-marrow-biopsy/MY00305 through http://www.mayoclinic.com. Accessed on 1/4/09.
Riley, R. et. al An Illustrated Guide to Performing the Bone Marrow Aspiration and Biopsy. Virginia Commonwealth University Department of Pathology [On-line information]. PDF available for download at http://www.pathology.vcu.edu/education/lymph/How%20to%20Marrow.pdf through http://www.pathology.vcu.edu. Accessed on 1/4/09.
Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition]. Pp 1163.
Sources Used in Previous Reviews
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Nanda, R. (2005 February 3, Updated). Bone marrow aspiration. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003658.htm.
Vergidis, D. (2004 June 28). Bone Marrow Aspiration and Biopsy. EMedicine [On-line information]. Available online at http://www.emedicine.com/med/topic2971.htm#section~procedure through http://www.emedicine.com.
Nanda, R. (2005 February 1, Updated). Bone marrow biopsy. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003934.htm.
(©1999-2003). Bone marrow aspiration and biopsy. Dr. Joseph F. Smith Medical Library [On-line information]. Available online at http://chclibrary.org/micromed/00040370.html through http://chclibrary.org.
Falck, T. (© 2003). Bone Marrow Biopsy. Emedicine Consumer Health [On-line information]. Available online at http://www.emedicinehealth.com/articles/4945-1.asp# through http://www.emedicinehealth.com.
(© 1995-2005). Bone Marrow Examination. Merck Manual Second Home Edition [On-line information]. Available online at http://www.merck.com/mmhe/sec14/ch170/ch170c.html?qt=%22bone%20marrow%22&alt=sh#fg170_1 through http://www.merck.com.
(© 1995-2005). Stem Cell Transplantation. Merck Manual Second Home Edition [On-line information]. Available online at http://www.merck.com/mmhe/print/sec16/ch187/ch187h.html through http://www.merck.com.
Sondheimer, N. (2005 April 20). Bone Marrow Aspiration And Biopsy. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/print/ency/article/003935.htm.
(April 2002). Bone and Marrow Stem Cell Transplantation: Leukemia, Lymphoma, and Myeloma. The Leukemia and Lymphoma Society [On-line information]. PDF available for download at http://www.leukemia-lymphoma.org/attachments/National/br_1018986496.pdf through http://www.leukemia-lymphoma.org.