The marrow aspiration is usually performed before a biopsy is done. A syringe is attached to the needle, the plunger is pulled and 1.0-1.5 ml. of marrow particles and blood from marrow sinuses is withdrawn. If additional bone marrow samples are needed, a separate syringe must be used each time. If more than 2 cc. per syringe is taken out, the blood to marrow ratio will be too high and the preparations will not accurately reflect the marrow contents. As the marrow is aspirated into the syringe the patient will feel some pain and pressure even though local anesthetic has been administered.
