A trephine biopsy is a medical procedure used to take a small, solid piece of bone marrow tissue so that it can be examined under a microscope. The bone marrow is the soft, spongy tissue inside bones where most blood cells are made. Pathologists use the sample from a trephine biopsy to see how the bone marrow is organized and whether it is healthy or affected by disease.
The term “trephine” comes from the special type of hollow needle used in the procedure. This needle removes a narrow core of bone and marrow together, allowing the pathologist to examine the structure of the tissue in its natural state.
A trephine biopsy is usually done when doctors need more information than can be obtained from a bone marrow aspirate alone. While an aspirate collects liquid marrow to study individual cells, a trephine biopsy provides a solid piece of tissue that shows:
The overall architecture of the bone marrow.
How different types of blood cells are arranged.
Whether there is fibrosis (scarring) in the marrow.
Whether abnormal clusters of cells, such as cancer cells, are present.
Doctors may request a trephine biopsy to investigate:
Unexplained changes in blood counts.
Suspected blood cancers such as leukemia, lymphoma, multiple myeloma, or myelodysplastic syndromes.
Other cancers that may have spread to the bone marrow. This is called a metastasis.
Non-cancerous conditions such as nutrient deficiencies, chronic infections, or bone marrow scarring disorders.
The biopsy is usually taken from the hip bone, most often the back part of the pelvis called the posterior iliac crest. After numbing the area with local anesthetic, the doctor inserts the trephine needle into the bone and removes a small core of bone marrow tissue. The procedure usually takes only a few minutes.
You may feel pressure or some discomfort, but the anesthetic helps minimize pain. Most people are able to go home the same day.
A trephine biopsy can reveal many different types of findings about the bone marrow. Some results describe whether the overall number of blood-forming cells is normal, increased, or decreased, while others focus on whether the three major blood cell lineages are present and developing properly. The report may also comment on the presence of abnormal or cancerous cells, scar tissue, or changes in iron storage. These details help your doctor understand how well your bone marrow is working and whether there are signs of disease.
Your report may use terms such as:
Normocellular marrow: The number of cells is normal for your age.
Hypercellular marrow: There are more developing blood cells than expected, which may be seen in leukemia, myeloproliferative neoplasms, or as a response to infection.
Hypocellular marrow: There are fewer developing cells than expected, which may occur in aplastic anemia or after chemotherapy.
Trilineage hematopoiesis: All three major blood cell lineages are present and developing normally.
Blasts: An increased number of immature cells may suggest leukemia.
Spread of cancer: Cancer from another site or lymphoma involving the bone marrow.
Fibrosis: Increased scar tissue that may interfere with normal marrow function.
Although both tests are often performed during the same procedure, they provide different but complementary information:
A bone marrow aspirate removes a small amount of liquid marrow. It allows pathologists to study individual cells in detail, including their size, shape, and maturity. This test is excellent for spotting abnormal-looking cells but does not show how the cells are arranged within the marrow.
A trephine biopsy removes a solid core of tissue. It allows pathologists to see the overall structure of the marrow, including cell organization, the presence of scar tissue (fibrosis), and abnormal clusters of cells.
Together, these tests give the most complete picture of bone marrow health and are often performed side by side.
Why was a trephine biopsy recommended for me?
What did my trephine biopsy show about my bone marrow?
Were all three types of blood cell lineages present and normal?
Was the marrow described as normocellular, hypercellular, or hypocellular?
Were there any abnormal or cancerous cells in the sample?
How will these results affect my treatment plan or follow-up?