Bone Marrow Evaluation

What is a bone marrow aspirate and when is it indicated?

A bone marrow aspirate is a procedure where a sample of cells within the bone marrow is aspirated and evaluated on a slide.  Bone marrow is located within the center cavity of bones and is the organ where blood cells (ie red blood cells, white blood cells, and platelets) are produced. This procedure will show signs of disease, and is generally indicated when patients exhibit abnormalities on a CBC, such as anemia (low red blood cell count), thrombocytopenia (low platelet counts), leukopenia (low white blood cell counts), severely elevated blood cell counts (which can indicate leukemia), or abnormal cells circulating in the blood stream. 

How is bone marrow aspiration used in cancer patients?

In patients with suspected cancer, a bone marrow aspirate may be indicated for staging (like with lymphoma and high grade mast cell tumors) or utilized as a method of evaluating response to therapy.  This procedure may also help reveal cancer in a patient with bloodwork abnormalities that does not appear to have cancer elsewhere in the body (such as in patients with multiple myeloma). 

How is bone marrow aspiration performed?

Patients are generally heavily sedated or placed under light anesthesia to minimize discomfort associated with the procedure.  The area over the bone is shaved (just a small square) and cleaned thoroughly, and a small needle with syringe is used to inject local anesthetic (usually lidocaine) into the bone and overlying subcutaneous tissue and skin.  A large needle is inserted through the skin and into the bone, and is slowly advanced through the outer cortex; once the needle is through into the bone marrow, a syringe is connected and a sample of marrow is aspirated (sucked into the syringe).  The needle and syringe are quickly removed, and the material (which looks similar to blood) is spread on slides and sent to a clinical laboratory for evaluation.  

The most common bones used for bone marrow aspiration include the upper forearm, the hip bone, the upper thigh, the shin, or the ribs.   The procedure takes roughly 5-10 minutes, and is very safe.  While profuse bleeding and/or fracture of bones is a risk, this is exceedingly rare and almost never happens.

Is this procedure painful?

Precautionary measures are taken to make sure this procedure is as pain-free as possible.  A local anesthetic is used to minimize discomfort associated with insertion of the needle, and the patient is generally heavily sedated or anesthetized to ensure that they do not feel pain during aspiration.  While some patients are slightly uncomfortable for 12-48 hours after the procedure, this can be alleviated with oral pain medications.