Bone Marrow Examination – Meaning, Procedure & Result Guide

What is Bone Marrow Examination?

Bone Marrow Examination is a specialized diagnostic procedure used to study the soft tissue inside the bones, known as bone marrow.
This tissue plays a vital role in producing blood cells — red blood cells (RBCs), white blood cells (WBCs), and platelets.

The test helps doctors evaluate bone marrow function, detect blood-related disorders, and monitor the response to treatments like chemotherapy.

There are two main types of bone marrow tests:

1. Bone Marrow Aspiration – A small liquid sample of bone marrow is collected.
2. Bone Marrow Biopsy – A solid core sample of bone marrow tissue is removed for detailed examination.

Together, these procedures provide a complete picture of how well the bone marrow is functioning and whether any abnormal or cancerous cells are present.

Where It Is Synthesized/Produced in the Body

Bone marrow is located within the central cavities of large bones such as:

• Pelvis (hip bone)
• Sternum (breastbone)
• Femur (thigh bone)
• Vertebrae (spine)

Inside the bone marrow, there are hematopoietic stem cells — immature cells that can develop into:

• Red Blood Cells (RBCs): Carry oxygen to tissues.
• White Blood Cells (WBCs): Defend against infections.
• Platelets: Help in clotting and prevent bleeding.

The bone marrow is thus the factory of the body’s blood cells and plays a crucial role in immunity, oxygen transport, and bleeding control.

Main Functions and Importance of Bone Marrow Examination

Bone marrow examination provides vital diagnostic information about blood production, bone marrow health, and the presence of abnormal cells.

1. Evaluates Blood Cell Production

• Helps assess whether bone marrow is producing adequate numbers of red cells, white cells, and platelets.
• Detects pancytopenia (low counts of all cell types).

2. Diagnoses Bone Marrow Disorders

• Identifies serious diseases such as:
  • Leukemia (blood cancer)
  • Lymphoma
  • Multiple Myeloma
  • Aplastic Anemia
  • Myelodysplastic Syndrome (MDS)
  • Myeloproliferative Disorders

3. Detects the Cause of Anemia or Infections

• Used when routine blood tests show unexplained anemia, persistent fevers, or low blood counts.
• Helps detect infections that involve or spread to the bone marrow (like tuberculosis or fungal infections).

4. Cancer Staging and Monitoring

• Determines whether cancers from other organs (like breast or prostate cancer) have spread to the bone marrow.
• Monitors how well the bone marrow is recovering after chemotherapy or bone marrow transplant.

5. Research and Genetic Testing

• Bone marrow samples are sometimes used for cytogenetic and molecular tests to detect genetic abnormalities in blood cancers.

Causes of Low or Abnormal Bone Marrow Findings

Low bone marrow activity (also called hypoplastic or aplastic marrow) means that the marrow is producing fewer blood cells than normal.

Common Causes Include:

1. Aplastic Anemia:
   • A condition where the bone marrow fails to produce enough blood cells.
   • Can be caused by autoimmune reactions, radiation, or certain drugs.
2. Chemotherapy or Radiation Therapy:
   • These cancer treatments suppress bone marrow function temporarily.
3. Nutritional Deficiencies:
   • Severe lack of vitamin B12, folate, or iron can slow blood cell formation.
4. Bone Marrow Infiltration:
   • Cancer cells (like leukemia or metastasis) may crowd out normal marrow cells.
5. Chronic Infections or Autoimmune Disorders:
   • Certain viral or bacterial infections may damage marrow activity.

Symptoms of Low or Abnormal Bone Marrow Function

When the bone marrow produces too few blood cells, symptoms depend on which type of cell is affected:

If all three are low (pancytopenia), it may indicate a serious bone marrow failure condition.

Causes of High or Abnormal Bone Marrow Findings

High bone marrow activity (called hypercellular marrow) indicates that the marrow is overproducing blood cells or responding to disease.

Common Causes Include:

1. Leukemia:
   • Overproduction of immature or abnormal white blood cells.
   • Seen in acute or chronic leukemias.
2. Myeloproliferative Disorders:
   • Conditions where the marrow produces too many RBCs, WBCs, or platelets.
   • Examples: Polycythemia Vera, Essential Thrombocythemia, Myelofibrosis.
3. Infections or Inflammation:
   • Marrow activity increases to produce more immune cells during severe infection.
4. Cancers Metastasizing to Bone Marrow:
   • Certain cancers (like lung, breast, or prostate cancer) can spread to bone marrow and alter its structure.

Symptoms of High or Abnormal Bone Marrow Activity

• Fever and night sweats (often due to leukemia or infection)
• Unexplained weight loss
• Bone pain or tenderness
• Swollen lymph nodes or spleen
• Abnormal bleeding or clotting (especially with platelet abnormalities)

These findings often point toward bone marrow cancer or serious hematologic disease requiring prompt evaluation.

Reference Ranges

Bone marrow examination does not have fixed numeric reference ranges like other blood tests.

Instead, results are interpreted microscopically by a pathologist based on:

• The cellularity (ratio of marrow cells to fat)
• The number and proportion of different cell types
• The presence of abnormal or immature cells
• Fibrosis or infiltration by cancer cells

A healthy bone marrow typically contains:

• 30–70% cells, depending on age (more cellular in young people)
• No malignant or abnormal cells

Sample Type and Procedure

1. Sample Type

• Bone Marrow Aspirate: Liquid portion of marrow (for cellular detail and cytology).
• Bone Marrow Biopsy: Solid core tissue (for architecture and overall structure).

2. Common Collection Sites

• Posterior iliac crest (hip bone): Most commonly used.
• Sternum (breastbone): Sometimes used in adults.
• Tibia (shin bone): Used in infants or small children.

3. Procedure Steps

1. The area is cleaned and numbed using local anesthesia.
2. A special needle is inserted into the bone.
3. A small amount of liquid marrow (aspirate) is collected first.
4. Then a small core of solid tissue (biopsy) may be taken.
5. The samples are sent to the laboratory for examination under a microscope.

The procedure takes about 15–20 minutes and may cause mild discomfort or pressure but is generally safe.

Test Preparation

• Fasting is not required.
• Inform your doctor about:
  • Any bleeding disorders or use of blood thinners.
  • Allergies to anesthetic agents.
• The area may be numb for a few hours after the test.
• Avoid heavy exercise or pressure on the biopsy site for a day.

When to Consult a Doctor

You should consult a hematologist or doctor if you experience:

• Unexplained fatigue, weakness, or pale skin
• Frequent infections or fevers
• Easy bruising or prolonged bleeding
• Unexplained weight loss, bone pain, or swollen glands
• Abnormal CBC (Complete Blood Count) results

Bone marrow examination may be recommended to confirm or rule out:

• Leukemia, lymphoma, or multiple myeloma
• Aplastic anemia or pancytopenia
• Myelodysplastic or myeloproliferative disorders

Important Word Explanations

~END~