A bone marrow aspiration is a medical procedure in which a small amount of liquid bone marrow is removed using a thin needle and suction. The sample is then spread onto glass slides so that the individual cells can be examined under a microscope by a pathologist. Because the aspiration provides a detailed look at individual cells, it is very useful for studying their size, shape, maturity, and number.
Aspirations are performed when doctors need to understand how the bone marrow is producing blood cells or to investigate possible diseases that affect the bone marrow.
Reasons for performing a bone marrow aspiration include:
Unexplained blood abnormalities: If blood tests show low or high levels of red blood cells, white blood cells, or platelets.
Suspected blood cancers: Such as leukemia, lymphoma, multiple myeloma, or myelodysplastic syndromes.
Other cancers: To check if cancer from another part of the body has spread to the marrow. This type of spread is called a metastasis.
Non-cancerous conditions: Such as nutritional deficiencies (iron, B12, or folate), infections, or autoimmune diseases.
Monitoring treatment: To evaluate how well the bone marrow is recovering after chemotherapy, bone marrow transplant, or other therapy.
The aspiration is usually taken from the hip bone, often the back part of the pelvis called the posterior iliac crest. After the skin is numbed with local anesthetic, a thin hollow needle is inserted into the bone. A syringe is then attached, and a small amount of liquid marrow is drawn out. The procedure is usually quick, although you may feel pressure or a brief, sharp pulling sensation when the marrow is removed.
A bone marrow aspiration can provide many important details about how the bone marrow is functioning. The report may describe whether the overall number of developing blood cells is normal, increased, or decreased, and whether all three main types of blood cells are present and maturing as expected. Pathologists also comment on the number of immature cells (called blasts), the appearance of developing cells, and the presence of any abnormal or cancerous cells. Together, these findings help your doctor understand the health of your bone marrow and guide further testing or treatment if needed.
Your report may include terms such as:
Normocellular marrow: The number of cells is normal for your age.
Hypercellular marrow: There are more blood-forming cells than expected, often seen in leukemia, myeloproliferative neoplasms, or as a response to infection.
Hypocellular marrow: There are fewer blood-forming cells than expected, which can occur in aplastic anemia or after chemotherapy.
Trilineage hematopoiesis: All three main types of blood cells are present and developing normally.
Left shift: More immature cells than expected, sometimes as a response to infection.
Maturation arrest: Developing cells stop before reaching maturity, which is abnormal and may suggest bone marrow disease.
Although both tests are often performed together, they provide different but complementary information:
A bone marrow aspiration provides liquid marrow for studying individual cells in detail. It is excellent for identifying abnormal cell shapes and counting the number of blasts or other rare cells.
A trephine biopsy provides a solid piece of tissue that shows the overall structure of the marrow, including fibrosis (scarring) or abnormal clusters of cells.
Together, they give the most complete picture of bone marrow health.
Why was a bone marrow aspiration recommended for me?
What did my bone marrow aspiration show?
Were all three blood cell lineages present and normal?
Was my bone marrow described as normocellular, hypercellular, or hypocellular?
Were any abnormal or cancerous cells seen?
Do I need a trephine biopsy as well, and how do the results compare?
How will these findings affect my treatment or follow-up plan?