Bone marrow aspiration and trephine biopsy are essential diagnostic procedures in the fields of hematology and oncology, offering essential information regarding the condition, pathology and functioning of the bone marrow. These methods are vital for identifying a variety of hematological disorders, such as leukemia and lymphoma etc.

Background Information

What is Bone Marrow?

Bone marrow is a soft, jelly-like tissue located within the bone cavities. It plays a key role in hematopoiesis, the process of generating blood cells, which includes red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). There are two main types of bone marrow:

• Red marrow: Involved actively in hematopoiesis.
• Yellow marrow: Mainly made up of fat and does not participate in blood cell production.

What is Bone Marrow Aspiration?

Bone marrow aspiration consists of extracting a small amount of liquid bone marrow through a thin needle. Typically, the sample is obtained from the posterior iliac crest (pelvis) in adults, although it can also be taken from the sternum (breastbone) in certain situations. This procedure is carried out under local anesthesia and yields a sample for cytological analysis.

What is Bone Marrow Trephine Biopsy?

A trephine biopsy, or core biopsy, entails the removal of a small core of bone marrow tissue, including a portion of the bone. This method offers a more detailed examination of the bone marrow architecture, such as cellularity, fibrosis, and the presence of abnormal cell infiltration. It is frequently performed in conjunction with aspiration to enhance the diagnostic findings.

Historical Context of Bone Marrow

• 1868-  Neuman  and  Bizzazero  squeezed  the marrow from rib of human cadaver.
• 1876-  Mosler  use  a  regular  wood  drill  to  obtain marrow particle.
• 1929, Dr. Mikhail M. Wintrober performed the first successful bone marrow aspiration by utilizing a sternal puncture to collect marrow samples. Throughout the years, these techniques have progressed, featuring advancements in needle designs, imaging guidance, and processing techniques, which have improved the safety and diagnostic effectiveness of these procedures.

Indications for Bone Marrow Aspiration and Trephine Biopsy

These procedures are indicated for:

• Diagnosis of Hematologic Disorders:
  • Acute and chronic leukemia
  • Lymphoma
  • Multiple myeloma
  • Myelodysplastic syndromes (MDS)
  • Aplastic anemia
• Evaluation of Unexplained Cytopenias:
  • Anemia (decrease in red blood cells)
  • Thrombocytopenia (decrease in platelets)
  • Neutropenia (decrease in white blood cells)
• Staging of Hematologic Malignancies:
  • Determining the degree of disease involvement.
• Infectious Diseases:
  • Identifying infections such as tuberculosis, histoplasmosis, or leishmaniasis.
• Monitoring Treatment Response:
  • Assessing the success of chemotherapy or immunotherapy.
• Stem Cell Harvesting:
  • Obtaining bone marrow for transplantation.

Sites For Bone Marrow Aspiration

What are the sites for bone marrow aspiration?

1. Posterior superior iliac spine/crest (PSIS/C):

This is the preferred location for adults and children older than two years. It allows for multiple punctures at once and the collection of larger amounts of bone marrow. It is considered safe, and since it is not visible to the patient, it tends to induce less anxiety. A bone marrow trephine biopsy can also be conducted from this location with the same skin entry point.

2. Sternum:

The sternum is appropriate for obese adult patients. It can be punctured at the second or third intercostal space, slightly off the midline. The sternum has a thickness of approximately 1.5 cm, so a guard should be utilized on the needle to limit penetration to no more than 0.5 cm into the bone.

3. Spinous process of vertebrae:

The spinous processes may also be considered for bone marrow aspiration, but it is important that they are palpable. This site is not commonly chosen.

4. Tibia:

For children under the age of 2, the anteromedial surface of the tibia, just below the tibial tuberosity, is the preferred site.

5. Anterior superior iliac spine:

While this location can be used for obese individuals, it is not ideal. It is more painful due to the high concentration of sensory nerves in the skin, has thicker overlying cartilage, and is more acute, leading to less marrow presence, particularly in older patients.

6. Others site:

In certain instances, aspiration can be directly carried out from a visible lesion observed on X-ray, such as lytic lesions in the ribs or skull bones.

What are the best sites for bone marrow aspiration?

The fluid from the bone marrow (aspirate) and the tissue sample (biopsy) are typically obtained from the upper edge of the hipbone at the back (posterior iliac crest). In certain cases, the front of the hip may also be utilized.

What is the most common site for bone marrow aspiration in infants?

In children under 18 months old, the anteromedial aspect of the tibia is the recommended location for marrow aspiration; however, inexperienced technicians may find this site insufficient for obtaining adequate samples, and there is a possibility of fracturing the bone during the procedure.

Procedure of Bone Marrow Aspiration

Requirements

• Bone Marrow Aspiration needle
  • Should be stout and made of hard stainless steel.
  • About 7-8cm in length with a well fitting stylet provided with a  adjustable guard to prevent over penetration.
  • The most commonly used needle is Salah, Klima or Islam. First two needles are provided with a guard and are suitable for aspiration from all sites.
  • Islam needle is not provided with a guard but it is longer than others and has holes on the sides that permit collection of better representative sample. It can only be used on PSIS/C.
• Glass slides that are clean and free of grease, ideally featuring a frosted end for convenient labeling.
• A spreader.
• A large piece of filter paper.
• 10 ml disposable syringes.
• 20-50 ml disposable syringes with a nozzle compatible with the aspiration needle.
• Antiseptic lotion containing 0.5% chlorhexidine in ethanol.
• Local anesthetic in 2% lignocaine.
• A surgical blade attached to a handle.
• Surgical towels.
• Disposable surgical gloves.
• Towel clamps.
• Sponge forceps.
• A medicine bowl.
• Sterile surgical gauze.

Procedure

1. Gather all necessary items on the tray or trolley.
2. Set a piece of filter paper and arrange 2-3 glass slides at an angle against a support on it.
3. Mark at least 10 slides with patient identification and prepare for smear preparation.
4. Draw approximately 5 ml of 2% lignocaine into a disposable syringe and set it aside for later use.
5. Wash your hands thoroughly with soap and water, and then put on surgical gloves.
6. Explain the procedure to the patient and provide reassurance. Make sure to address the potential suction pain.
7. Position the patient based on the area selected for aspiration.
8. Clean the site with an antiseptic solution, ensuring to cover a larger area than needed to avoid infection.
9. Use surgical towels to drape the area.
10. Inject lignocaine into the skin, subcutaneous tissue, and periosteum of the bone in an area of about 1-2 cm. Allow 3-5 minutes for the anesthetic to take effect.
11. Use a blade to make a small, shallow incision at the chosen site.
12. Introduce the aspiration needle using a gentle boring motion. When the needle enters the bone marrow, there will be a noticeable reduction in resistance. Advance the needle slightly more until it feels secure.
13. Remove the stillet and attach a disposable syringe of 30-50 ml to the needle.
14. Aspirate around 0.5 ml of marrow. A sign that the marrow has been adequately entered is the sensation of suction pain.
15. Detach the syringe and reinsert the stillet.
16. Immediately begin preparing the smears to prevent clotting of the marrow. This is done by pouring the aspirated marrow onto the angled slides, allowing the free blood to flow away while the fragments adhere to the slide. Use the edge of the spreader to pick up the fragments and gently smear them onto the pre-prepared slides.
17. Place any remaining marrow in an EDTA bottle and mix it well to allow for the preparation of additional slides if necessary.
18. Achieve hemostasis by applying firm pressure on the puncture site for 5-10 minutes.
19. If necessary, a stitch may be placed in the incision.
20. Apply a dressing over the site.

Risk Involved In Bone Marrow Aspiration

• People with bleeding problems have a higher chance of bleeding  from biopsy site. If patients have bleeding problems, pressure  will be put on the biopsy site for at least 10 minutes after the  biopsy. In rare cases, patients may be given a blood product  (clotting factor or platelets) in a vein in arm before the  aspiration to prevent bleeding after the aspiration/biopsy.
• Infection of skin or the bone at the biopsy site, especially in  people with compromised immune system.
• Injury to heart, a lung, or a major blood vessel if the sample is  taken from the sternum. This complication is very rare.
• Pain after the procedure.

What is the most commonly used anticoagulant for bone marrow studies?

• Chromosome/ PCR/  Cytogenetic studies: Place at least 0.5ml of the  bone marrow aspirate in  Sodium Heparin tube and  EDTA tube.
• For Flow  Cytometry: Place as much bone marrow  aspirate as possible into a  sterile EDTA tube and mix.

Recent Developments in Bone Marrow Aspiration

• Imaging Assistance
  • The employment of ultrasound or fluoroscopy has enhanced the precision and safety of bone marrow procedures, especially in obese individuals or those with complex anatomical structures.
• Molecular Testing
  • Methods like next-generation sequencing (NGS) and digital PCR have improved the detection of genetic mutations and minimal residual disease, providing high sensitivity.
• Circulating Tumor DNA Analysis
  • Although it cannot replace bone marrow biopsy, liquid biopsy (which examines circulating tumor DNA) provides a less invasive option for tracking disease progression and evaluating treatment responses.
• Machine Learning
  • AI-based algorithms are being created to evaluate bone marrow samples, boosting diagnostic precision and decreasing variability between observers.

Challenges and Limitations

• Technical Difficulties Patient Discomfort: These procedures can cause pain, although local anesthesia can help alleviate this.
• Sampling Challenges: Insufficient samples may result in uncertain diagnoses.
• Risks: There are rare but serious risks such as bleeding, infection, or nerve damage.
• Diagnostic Constraints Subtle Indicators: Early-stage diseases might display nonspecific or subtle changes in the bone marrow.
• Fibrosis: In conditions such as myelofibrosis, obtaining a sufficient sample can be challenging.
• Ethical and Practical Issues Patient Worry: Some individuals may feel considerable anxiety regarding the procedure.
• Financial and Access Issues: Cutting-edge diagnostic methods may not be accessible in settings with limited resources.