Bone Marrow Aspiration Surgical Technique

Bone marrow aspiration is a critical diagnostic and therapeutic procedure used in the evaluation of hematologic disorders, malignancies, infections, and marrow involvement by systemic diseases. The technique involves the percutaneous withdrawal of a small amount of liquid bone marrow, typically from the posterior iliac crest, for cytologic and morphologic examination. Mastery of the bone marrow aspiration technique is essential for clinicians, hematologists, pathologists, and surgeons alike to ensure accurate sample collection with minimal patient discomfort and complications.

Anatomical Considerations

The preferred site for bone marrow aspiration is the posterior superior iliac spine (PSIS) due to its accessibility and the thickness of marrow space. In infants and very young children, the anterior iliac crest or the tibia may be used because of developmental differences in marrow distribution. The sternum is less commonly employed due to the risk of injury to vital mediastinal structures and its thinner cortical bone.

Understanding the anatomy and landmarks is fundamental to safely perform the procedure:

• Posterior Superior Iliac Spine (PSIS): The PSIS is the palpable bony prominence on the posterior iliac crest. It is identified by palpating the iliac crest from behind and is the ideal site for aspiration.
• Cortical and Cancellous Bone: The aspiration needle must traverse the cortical bone to reach the medullary cavity that contains the marrow. The cortex at the PSIS can be relatively thick but is usually negotiable with the recommended needles.
• Adjacent Structures: Awareness of nearby nerves, muscles, blood vessels, and soft tissues prevents inadvertent injury during needle insertion.

Indications and Contraindications

Indications

• Diagnosis and staging of hematologic malignancies (e.g., leukemia, lymphoma, multiple myeloma).
• Evaluation of unexplained cytopenias.
• Assessment of marrow infiltration in metastatic cancers.
• Investigation of suspected marrow infections.
• Monitoring marrow response to therapy.
• Obtaining marrow for cytogenetics, flow cytometry, molecular studies.

Contraindications

• Absolute: Cellulitis or infection over the puncture site; severe coagulopathy not correctable; lack of patient cooperation when sedation or anesthesia is not applicable.
• Relative: Osteoporosis or prior irradiation of the iliac crest; anatomical deformities; thrombocytopenia (may require platelet transfusion or alternative strategy); severe obesity complicating landmark localization.

Preoperative Preparation

Proper preparation minimizes patient anxiety and procedural complications:

• Informed Consent: Discuss procedure, benefits, risks, and alternatives. Answer patient queries to ensure understanding and voluntary participation.
• Medical History and Physical Exam: Evaluate bleeding risk, allergies, and ability to lie still during the procedure.
• Laboratory Evaluation: Check coagulation profile, platelet count, and hemoglobin level where indicated.
• Patient Positioning: Typically, the patient is positioned prone or in lateral decubitus with the side of aspiration uppermost. This provides optimal access to the PSIS.
• Site Preparation: The skin overlying the PSIS is cleaned with antiseptic solution such as chlorhexidine or povidone-iodine. A sterile field is maintained throughout the procedure.
• Anesthesia: Local anesthesia (e.g., 12% lidocaine without epinephrine) is infiltrated subcutaneously and into periosteum at the puncture site to minimize pain.

Equipment Required

• Sterile bone marrow aspiration needle (e.g., a 15-gauge, 1.52 inch specialized aspiration needle with stylet).
• 10ml or 20ml syringes.
• Antiseptic skin prep solutions.
• Local anesthetic agent and supplies for injection (syringe, needles).
• Sterile gloves, drapes, gauze pads, bandages.
• Collection tubes for marrow samples (EDTA tubes for cytogenetics, slides for smears, culture bottles if infection is suspected).
• Sharps disposal container.

Step-by-Step Surgical Technique

1. Patient Positioning and Site Identification

Place the patient in prone or lateral decubitus position with the uppermost hip abducted slightly. Palpate the PSIS by running fingers along the iliac crest posteriorly. Mark the site approximately 2 cm medial and inferior to the PSIS for needle insertion.

2. Skin Preparation and Local Anesthesia

Apply antiseptic solution using a circular motion starting at the marked site and moving outward. Allow the site to air dry for maximal antisepsis. Next, inject 13 ml of local anesthetic into the skin and subcutaneous tissues down to the periosteum, aspirating before each injection to avoid intravascular administration.

3. Needle Insertion

Remove the stylet from the marrow aspiration needle. Holding the needle perpendicular (at a 90-degree angle) to the bone surface, apply steady but moderate pressure while rotating the needle clockwise. The needle should penetrate the skin, subcutaneous tissue, and advance through the cortical bone of the iliac crest. A tactile give or sudden loss of resistance indicates entry into the marrow cavity.

4. Aspiration of Bone Marrow

Attach a 10ml syringe to the needle hub. Apply a quick, steady negative pressure by pulling back the syringe plunger to aspirate 0.5 to 1 ml of marrow. Excessive suction or slow aspiration risks dilution with peripheral blood. Immediately release suction and detach the syringe once the aspirate is obtained.

5. Sample Handling

Transfer small drops of marrow aspirate onto glass slides to prepare smears by spreading with another slide at a 45-degree angle. Allow the slides to air dry. Collect additional marrow aspirate in anticoagulated tubes for flow cytometry, cytogenetics, or molecular studies as indicated.

6. Needle Removal and Site Care

Replace the stylet to prevent contamination during withdrawal. Remove needle gently, apply firm pressure for several minutes to prevent bleeding or hematoma formation. Clean the site again and cover with a sterile adhesive dressing.

7. Observation and Aftercare

Observe the patient for 15 to 30 minutes post-procedure for any immediate complications such as bleeding, pain, or dizziness. Provide verbal and written instructions on care of the puncture site and signs of complications to monitor.

Tips for Optimal Technique and Sample Quality

• Aspiration from the PSIS generally yields the best samples; avoid multiple punctures to reduce patient discomfort and risk of complications.
• Use a fresh needle if repeated aspirations are required to minimize contamination and shearing of cellular elements.
• Limit aspiration volume per attempt (0.51 ml) to avoid peripheral blood dilution, which can interfere with accurate diagnosis.
• Prepare bone marrow smears promptly to preserve cellular morphology.
• Communicate clearly with the laboratory regarding special requests such as flow cytometry or molecular testing to ensure proper sample collection and handling.

Potential Complications and Management

Common Complications

• Pain and Discomfort: Usually mild and transient, controlled with adequate local anesthesia and reassurance.
• Bleeding and Hematoma: Minimized by careful technique and firm post-procedural pressure. Significant bleeding is rare but requires prompt evaluation.
• Infection: Rare with strict aseptic technique; delayed local infections may require antibiotics.

Rare but Serious Complications

• Needle breakage within the bone.
• Injury to adjacent neurovascular structures especially if performed improperly on sites other than the iliac crest.
• Osteomyelitis or osteonecrosis at the puncture site.

Early recognition and appropriate management of complications ensure patient safety and reduce morbidity.

Conclusion

Bone marrow aspiration remains a cornerstone procedure in the diagnosis and management of numerous hematologic and systemic diseases. Meticulous knowledge of anatomy, careful patient preparation, and adherence to proper surgical technique are critical for safe and effective sample collection. Ensuring optimal specimen quality and minimizing complications directly impact diagnostic accuracy and patient outcomes. As with all invasive procedures, continued training, experience, and adherence to evidence-based protocols promote best practices and maintain patient safety.