Performing bone marrow aspiration and biopsy in children: Recommended guidelines

Abstract

Bone marrow aspiration (BMA) and bone marrow trephine biopsy are important procedures for the diagnosis of hematological malignancies and nonmalignant diseases in children. During BMA, bone marrow particles are obtained for analysis including microscopic morphologic evaluations and differential counts. During a trephine biopsy, a core of bone marrow is obtained and processed for the evaluation of marrow cellularity and to rule out marrow involvement by solid tumours, lymphomas or other processes. These invasive procedures should only be performed by a trained individual following a standard operating technique. There are no clear published guidelines in the paediatric literature. Hence, the purpose of the present article is to provide guidelines for the performance of BMAs and bone marrow trephine biopsies in children that will be useful for both general paediatricians and paediatric hematologists and oncologists.

COMMON CLINICAL INDICATIONS FOR BONE MARROW ASPIRATION

1. To investigate children with abnormal peripheral blood findings (eg, atypical cells [or blasts], pancytopenia, unexplained anemia, leukopenia or thrombocytopenia);

2. To diagnose malignant hematological disorders, hypoplastic anemias, inherited bone marrow failure syndromes and metastatic spread of tumours (1–3);

3. To obtain microbiological cultures in children with fever of unknown origin;

4. For investigation of hypersplenism, lymphadenopathy, mediastinal or abdominal masses; and

5. For follow-up after chemotherapy or hematopoietic stem cell transplant (3).

COMMON CLINICAL INDICATIONS FOR BONE MARROW TREPHINE BIOPSY

1. Inadequate or failed marrow aspiration;

2. Suspected bone marrow fibrosis;

3. Investigation and staging of Hodgkin’s and non-Hodgkin’s lymphoma, and small blue round cell tumours of childhood (neuroblastoma, rhabdomyosarcoma and Ewing’s sarcoma); and

4. Diagnosis of aplastic anemia, myelodysplastic syndromes and acute megakaryoblastic leukemia (AML-M7) (4).

TECHNIQUE

The preferred site for obtaining bone marrow in children is the posterior superior iliac crest because it contains the most cellular marrow, there are no vital organs in close proximity and it is a nonweight-bearing structure (3). The anterior iliac crest is preferable in very obese patients. In children younger than 18 months of age, the anteromedial face of the tibia is preferred for marrow aspiration (3); however, this site may fail to yield adequate samples when the procedure is performed by an inexperienced technician; there is also a risk of fracturing the bone. At The Hospital for Sick Children (Toronto, Ontario), the posterior superior iliac crests for all children, including small infants, is preferred.

Trephine biopsies are usually taken from the posterior superior iliac crest in children; however, a technique using the tibia has been described for small neonates (5). Bone marrow aspiration (BMA) and bone marrow trephine biopsy (BMTB) must be performed only by experienced health care providers who have been well-trained in the technique (6).

CONTRAINDICATIONS

1. Hemorrhagic disorders such as congenital coagulation factor deficiencies (eg, hemophilia), disseminated intravascular coagulation and concomitant use of anticoagulants.

   If a BMA or a BMTB is absolutely indicated in these patients, then factor replacement or cessation of anticoagu lation should be considered before the procedure, and the patient should be closely monitored for 24 h postprocedure Severe thrombocytopenia is not a contraindication to BMA, as long as prolonged pressure is applied to the site to prevent bleeding. For obese patients with severe thrombo cytopenia, in whom a bone marrow biopsy is indicated, it is preferable to perform a platelet transfusion to raise the platelet count to over 15 × 10⁹/L (3,4).

2. Skin infection or recent radiation therapy at the sampling site.

3. Bone disorders such as osteomyelitis or osteogenesis imperfecta.

PATIENT ASSESSMENT

1. Check primary diagnosis and treatment protocol to determine the need for the study and any special requirements (eg, flow cytometry, cytogenetic or molecular studies);

2. Obtain written consent from the guardian or the child, if deemed competent;

3. Assess need for sedation (eg, conscious sedation by an anesthesiologist [using intravenous propofol or inhaled nitric oxide] or general anesthesia). At The Hospital for Sick Children, children who weigh less than 10 kg and those with respiratory compromise undergo the procedure in an operating room (children with a mediastinal mass and those with severe respiratory distress should have an anesthesia assessment before the procedure);

4. Check the platelet count in all children, as well as the international normalized ratio and the partial thromboplastin time if the patient has a history of bleeding problems or is currently on anticoagulant therapy;

5. Assess skin at bone marrow site for signs of infection;

6. Check medical record for history of allergy to local anesthetics, iodine solutions or anesthetic medications;

7. Ensure all necessary personnel are present (eg, laboratory technician if cytogenetic studies are required);

8. Confirm patient identity; and

9. Consider the application of a topical anesthetic cream to marrow sampling site 30 min to 60 min before procedure.

EQUIPMENT

Ensure that an adequate number of syringes (some heparinized as indicated for the specimens to be collected) are prepared, and that any transport tubes containing, for example, EDTA (necessary for flow cytometry and molecular studies) are also available.

Refer to the on-line version of the guidelines for details on the equipment needed <www.pulsus.com>.

PREPARATION

Position the child on the procedure table (prone or lateral decubitus for posterior superior iliac crest, or supine for the anterior iliac crest) and expose the iliac crest. Ensure that the child is appropriately immobilized and that the airway is not compromised by positioning. Remove any topical ointments and clean the skin; palpate the iliac crest and locate the site of aspiration. Open the tray using sterile techniques, and wash and dress as required for sterile procedure. Wash the puncture site with antiseptic solution using a circular motion from the inner to the outer area, repeating the wash three times. Place sterile drapes over the operative site. It is the standard of care to anesthetize the marrow site with 1 mL to 2 mL of local anesthetic (1% to 2% lidocaine without adrenaline). The initial injection of the anesthetic solution should be intradermal with the needle parallel to the skin (bevel up to produce a wheal if using the posterior superior iliac crest), then slowly inject more deeply into the periosteum. In some institutions, the intradermal injection is not required if a topical anesthetic has been applied.

BMA

Puncture the skin with the BMA needle and advance to the periosteum, then enter the bone marrow space with a twisting motion until the needle is firmly anchored in the bone. Remove the stylet and attach a 5 mL syringe to the needle hub. Apply strong suction to obtain no more than 0.3 mL to 0.5 mL of bone marrow, disconnect the syringe from the needle and, if desired, reintroduce the stylet. Make or ask the technician to make smears from the aspirate immediately and verify that it contains particles. Using a new syringe, obtain additional samples as needed. Withdraw the aspiration needle and apply an adhesive bandage or pressure dressing. Document the procedure and any problems encountered in the patient’s chart. After transfer of the patient to a recovery area, monitor the patient and procedure site carefully. In instances of prolonged bleeding at the site, check the platelet count and the international normalized ratio and the partial thromboplastin time; occasionally, platelet and/or fresh frozen plasma transfusion may be required. At discharge, instruct the patient or the family to not use ibuprofen or acetylsalicylic acid for pain at the procedure site (because these drugs can cause platelet dysfunction), but to give codeine orally. Also, instruct to remove the dressing over the procedure site within 12 h because it may cause skin infection if it is left on for too long.

BMTB

A marrow biopsy and aspiration can be carried out through the same skin site. Position and prepare the patient as discussed earlier. Hold the needle with the proximal end in the palm and the index finger against the shaft near the tip. With the stylet locked in place, introduce the needle through the skin pointing toward the anterior iliac spine. Using gentle pressure, advance the needle with a slight twisting motion until it feels anchored to the bone; remove the stylet, then using alternating clockwise and counterclockwise motion, advance the needle slowly for 2 mm to 10 mm into the bone; the depth of the insertion depending on the size of the patient. Rotate the needle with three twists to the right and then to the left without advancing; repeat once again, then withdraw the needle using a rotary motion. Using a sterile gauze pad, apply manual pressure to the site until the bleeding stops. Remove the bone specimen from the biopsy needle by introducing a probe through the distal end (this prevents specimen crushing). An adequate biopsy in children should contain at least 0.5 cm of well-preserved bone marrow (7). Drop the specimen in formalin and label. If uncertain whether marrow particles have been obtained with the aspirate, before placing it in formalin, roll the biopsy specimen along a slide to obtain touch imprints (8). Refer to the on-line version of the guidelines for more details on technique <www.pulsus.com>.

INTERPRETATION OF RESULTS

The interpretation and reporting of marrow aspirates are the domain of qualified hematopathologists or hematologists. While some results from an aspirate may be available within hours, tests such as flow cytometry, molecular and cytogenetic analyses take longer. A bone marrow biopsy requires decalcification, and results will often only be available after two or more days.

COMPLICATIONS

BMA and BMTB are generally safe procedures with a low risk of morbidity. A review (9) of adverse events secondary to bone marrow examination showed an incidence of 0.08%. The most frequent adverse events were hemorrhage, infection and persistent pain at the marrow site. The bleeding episodes occurred mainly in the buttocks, thighs and retroperitoneum. Bleeding was particularly common among patients who had undergone both BMA and BMTB, or patients diagnosed with myeloproliferative disorders or osteoporosis (3,9). Patients with severe throm-bocytopenia, platelet dysfunction, coagulopathy, von Willebrand’s disease, renal impairment or obesity and those receiving acetylsalicylic acid, warfarin or heparin were also at risk (10). Breakage of the marrow needle has rarely been reported (3).

SUMMARY

BMA and BMTB are important investigations for the diagnosis and monitoring of many diseases. Significant adverse events related to these procedures are rare when they are properly performed. Standard operating guidelines are necessary for paediatric tertiary care centres performing BMAs and BMTBs.

Paediatric hematology and oncology trainees performing these procedures at our hospital are closely supervised during their first few sessions, and subsequently certified if deemed competent.