Bone Marrow Aspiration: A Method to Obtain Bone Marrow to Examine Cell Morphology

- Bone marrow, or the spongy tissue inside most bones, is the primary site of blood cell formation. Analysis of bone marrow cells helps in the accurate diagnosis of many blood-related disorders like leukemia. The posterior superior iliac spine is a readily accessible site and a rich source of bone marrow.

To obtain bone marrow aspirations, make the patient lie in a lateral decubitus position. Disinfect and anesthetize the intended aspiration site. Insert an aspiration needle and advance it through the skin, the subcutaneous tissue, and the cortical bone to access the spongy cancellous bone containing the bone marrow.

Remove the stylet of the needle and attach an empty syringe. Aspirate the bone marrow. Transfer a part of the aspirate into an anticoagulant-containing tube for storage without blood clotting. Transfer the remaining aspirate into a watch glass.

Locate tiny bone marrow cell aggregates or spicules and transfer one onto a glass slide. Gently glide a second glass slide over the spicule to form a smear. Dry and stain the smear for morphological examination of the bone marrow cells. The following protocol shows bone marrow sample aspiration from the posterior superior iliac spine of an acute myeloid leukemia patient for morphological evaluation of cells.

- With the patient in the lateral decubitus position, mark the superior posterior iliac spine with a pen and disinfect the skin of the intended biopsy area with 0.5% to 1% chlorhexidine in ethanol in an outward circular motion. After administering a local anesthetic, pick up a 15-gauge 2.8-inch needle with the proximal end in the palm and the index finger against the side of the metal shaft of the needle near the tip for control. Using gentle but firm pressure, introduce the needle with a quick alternating pronating/supinating movement through the anesthetized skin toward the iliac spine.

When the needle comes into contact with the posterior iliac spine, remove the stylet and attach an empty 10-milliliter syringe to the needle. Gently withdraw the plunger to create negative pressure within the syringe until up to 10 milliliters of bone marrow spicules have been harvested.

- Do not take more than 10 mils of bone marrow per aspirate to avoid hemodilution.

- Remove the syringe and place the stylet back onto the needle. Then eject about 2 milliliters of the marrow into a watch glass and ensure that enough sample is drawn to be injected into a heparin-coated 8-milliliter tube, and immediately invert the tube.

- To prevent clotting, it is important to invert the anticoagulant-containing tube as soon as the bone marrow is added.

- For optimal morphological assessment, use a plastic spatula to transfer spicules from the aspirate in the watch glass onto a glass slide, and carefully glide another glass slide on top of the marrow. After drying, stain the spicules with May-Grünwald-Giemsa for analysis by light microscopy. Place the bone marrow tube in a plastic holder and place the holder into a plastic container with an ambient gel pack and a completed request form.