Bone marrow is the soft material in the center of bones. In some bones, the bone marrow consists only of fat. Other bones contain what is termed cellular marrow. The cellular marrow has different types of cells that give rise to red cells, white cells and platelets that circulate in the blood. Sometimes the marrow may produce abnormal cells called “blasts” that may lead to blood cancer (leukemia).

What is a bone marrow aspiration and biopsy?
It is a technique for obtaining the marrow (bone marrow aspiration) or the inner core of bone (bone marrow biopsy) for investigation, diagnosis or for transplantation. The procedure consists of inserting a special needle into a bone that contains marrow and withdrawing the marrow by suction or coring out a sample of the marrow.

Why is bone marrow procedure required?
Most bone marrow procedures are performed to diagnose various conditions that affect the different types of blood cells for e.g. if the blood shows decrease in all 3 cell lines i.e. decrease platelets, red cells and white cells which may suggest decreased production in the bone marrow then a bone marrow procedure may be required. Another frequent reason is to diagnose certain cancers or to determine the extent of the cancer (cancer staging). This procedure can also be used to obtain marrow for transplantation.
A wide variety of conditions can be diagnosed by examination of the bone marrow. Cancers such as leukemia can be diagnosed by bone marrow examination. Decrease in any of the cells lines in the blood such as Idiopathic Thrombocytopenic Purpura, Sideroblastic anemia, Megaloblastic anemia, Aplastic Anemia can be diagnosed by bone marrow examination. Persistent fevers can be caused by infections that reside in the marrow and a bone marrow culture may establish the diagnosis.

What bone is used to sample the bone marrow?
The most frequent site for obtaining bone marrow is the hip bone. Other sites include the sternum (chest).

How is a bone marrow procedure performed?
Prior to the procedure, the patient is given pre-anesthetic medications consisting of a potent painkiller, sedative and atropine. A local anesthetic is injected at the procedure site to numb the skin and tissue down to the surface of the bone. A small nick is then made in the skin. A special needle called the bone marrow aspiration needle is used to penetrate through the dense outer shell of bone. Once inside the bone, the center portion of this needle (the trochar) is removed and a syringe is attached. The bone marrow is withdrawn by pulling back on the plunger of the syringe and collecting the liquid. This sample is known as the marrow aspirate. This part of the procedure only lasts a few seconds but is usually the most painful due to the sudden stimulation of small nerves inside the bone.

A biopsy may also be obtained in addition to the marrow aspirate. The same needle is used but without the center portion in place. As the needle is twisted through the bone it cuts a core which is trapped inside the needle. Once the needle is removed, this core can be extracted from the needle barrel.

Since the skin cut is usually very small, no stitches are generally necessary and only a bandage is applied.

What are the complications of a bone marrow procedure?
Patients may feel the pain caused by the procedure to a variable extent.

What is done with the bone marrow sample?
The bone marrow core biopsy is processed like other biopsies in the tissue study (histology) laboratory. The aspirate of the bone marrow is spread on glass slides and stained to make the bone marrow smears. The slides are then examined under the microscope, usually by a hematologist or pathologist. Portions of either sample may be submitted to the microbiology laboratory for cultures. Certain conditions may require other specialized studies such as genetic testing or cell marker studies.

Last updated on 01-06-2005