Bone Marrow Aspiration

Bone marrow biopsies can be done regardless of the platelet count and while the patient is on anticoagulation, provided that the INR is not severely abnormal (eg, INR ≥5). Care should be taken to maintain hemostatic pressure longer in patients with bleeding diatheses.

• Anesthesia: Local anesthesia is employed. General anesthesia is required for pediatric cases, some sternal bone marrow sampling cases, and in those patients who are highly anxious
• Positioning: The patient is placed in the lateral decubitus position, with the top leg flexed and the lower leg straight. Alternatively, the patient may be placed in the prone position.

Biopsy

Any of several needle models can be utilized; however, the Jamshidi needle has been the most popular. This disposable needle is tapered at the distal end to help retain the specimen for improved extraction. Powered drill devices have also been employed for this purpose and currently appear to yield comparable results.

Patient preparation is carried out in the manner previously described for bone marrow aspiration. Some kits allow aspiration and biopsy to be done with the same needle, which is convenient for the patient. However, if the latter is used, it is important to change the needle position slightly to a different area of bone after aspiration is obtained. Otherwise, an aspiration artifact is created where the marrow has been aspirated out of the core.

The needle, with stylet locked in place, is held within the palm and index finger and repositioned so that a new insertion site is created for biopsy sampling. Once the needle touches the bone surface, the stylet is removed.

With firm pressure applied, the needle is slowly rotated in an alternating clockwise-counterclockwise motion and advanced into the bone marrow cavity to obtain an adequate bone marrow specimen measuring approximately 1.6-3 cm in length.

The needle is rotated along its axis to help loosen the sample, pulled back approximately 2-3 mm, and then advanced again slightly, at a different angle, to help secure the specimen. After this procedure, the needle is slowly pulled out while being rotated in an alternating clockwise and counterclockwise motion.

The specimen is removed from the needle, and a probe is introduced through the distal cutting end. If the aspirate was unsuccessful (ie, a dry tap), the core biopsy may be used to make touch preparations .This must be performed before the specimen is placed in formalin. Finally, the specimen is placed in formalin solution for histologic processing.

Sternal bone marrow aspiration has a higher risk of complications than other sites because of the delicate bone structure in this area (~1 cm thick in adults). Penetration of the underlying mediastinal organs can result in mediastinitis, pulmonary embolism, pneumothorax, cardiac tamponade, and cardiac tissue injury, and for these reasons, biopsies are not to be performed from the sternum.

Awareness of anatomic variations and pathologies that may affect bone density (eg, osteoporosis and multiple myeloma) can prevent further complications and injuries.