Bone marrow biopsies take a small core of marrow tissue, usually together with a liquid aspirate, from the back of the hip bone (the posterior iliac crest) under local anesthetic. Doctors order them to explain abnormal blood counts, to diagnose and stage blood cancers such as leukemia, lymphoma, and myeloma, and to check how well treatment is working. The procedure usually takes about 20 to 30 minutes, serious complications are uncommon, and full results usually take several days to a couple of weeks once genetic tests are included.
In hematology, few tests answer as many questions at once. This guide covers the indications, technique, laboratory workup, and aftercare that clinicians and patients should understand.
What Is a Bone Marrow Biopsy?
A bone marrow examination usually involves two linked samples. The aspirate is liquid marrow drawn into a syringe, and the trephine biopsy is a solid cylinder of bone and marrow, typically 1.5 to 2 cm long. Together they show both individual cells and the overall architecture of the bone marrow tissue.
The marrow is the main site of blood production, generating on the order of 200 billion red blood cells a day in a healthy adult, along with white cells and platelets. Our bone marrow guide details how this tissue sustains healthy blood counts.
| Feature | Aspirate | Trephine (core) biopsy |
|---|---|---|
| Sample | Liquid marrow | Solid core of bone and marrow |
| Best for | Cell morphology, differential counts, flow cytometry, cytogenetics, molecular tests | Cellularity, architecture, fibrosis, infiltrates, granulomas |
| Turnaround | Smears can be read within a day | Needs decalcification, so usually several days |
| Limitation | “Dry tap” in fibrosis or packed marrow | Less detail on individual cell features |
Indications: When Is a Biopsy Needed?
The main purpose is to diagnose and monitor blood disorders that cannot be explained from the peripheral blood alone. Common indications include:
- Unexplained anemia, thrombocytopenia (low platelets), neutropenia, or pancytopenia.
- Unexplained leukocytosis, abnormal cells on the blood film, or suspected acute leukemia.
- Suspected myelodysplastic syndromes (MDS) or myeloproliferative neoplasms.
- Diagnosis and staging of multiple myeloma and some lymphomas.
- Unexplained splenomegaly, fever of unknown origin, or suspected infiltration by metastatic cancer.
- Assessment of response or residual disease after treatment, and before or after stem cell transplant.
These patients often present with symptoms that suggest hematological abnormalities, such as persistent fatigue, frequent infections, unexplained bruising, petechiae, night sweats, or weight loss. Frequently, though, the trigger is simply an abnormal complete blood count (CBC).
How the Procedure Is Performed
Before the Biopsy
The clinician reviews the blood count, clotting status, and medication list, especially anticoagulants and antiplatelet drugs. Informed consent is obtained, and the patient is told what sensations to expect. Most adults need only local anesthetic, sometimes with an oral anxiolytic or light sedation.
Step by Step
- The patient lies on their side or front, and the posterior iliac crest is identified by palpation.
- The skin is cleaned and local anesthetic is infiltrated down to the periosteum, the sensitive membrane covering bone.
- An aspiration needle is advanced into the marrow cavity and a few milliliters of marrow are drawn back. This moment often causes a brief, sharp, pulling pain.
- A trephine needle is then used to cut and remove the solid core.
- Pressure is applied and a dressing placed. The patient usually rests briefly before going home.
The sternum can be used for aspiration only, not for trephine biopsy, in selected adults. In young children, the anterior tibia is sometimes used.
Laboratory Analysis
The samples go to a hematopathology laboratory, where several tests are often run in parallel:
- Morphology: stained smears and sections are reviewed for cellularity, maturation, blasts, dysplasia, and infiltrates. Normal marrow cellularity falls with age, roughly as 100 minus the patient’s age, as a percentage.
- Immunohistochemistry: stains for markers such as CD34 or CD138 identify specific cell populations in the core.
- Flow cytometry: characterizes leukemia and lymphoma cells by their surface markers.
- Cytogenetics and FISH: detect chromosomal changes that define many leukemias and guide prognosis.
- Molecular testing: next-generation sequencing panels find gene mutations relevant to MDS and acute myeloid leukemia.
- Special stains: Perls’ stain for iron stores and reticulin stain for fibrosis.
A useful textbook threshold: acute myeloid leukemia is generally diagnosed when blasts reach 20% or more of marrow cells, while normal marrow contains fewer than 5% blasts.
Risks, Complications, and Aftercare
Bone marrow biopsies are generally safe. Most people have soreness at the site for a few days. Less common complications include bleeding or a hematoma, infection, and, rarely, injury to nearby structures. Risk is higher in patients with bleeding disorders, very low platelet counts, anticoagulant use, or immunosuppression, so these are addressed beforehand where possible.
After the procedure, patients should:
- Keep the dressing clean and dry for about 24 hours, and avoid baths or swimming until the site has healed.
- Use simple pain relief such as paracetamol (acetaminophen) if needed.
- Avoid strenuous activity for the rest of the day.
- Report bleeding that soaks the dressing, fever, spreading redness, or worsening pain.
How Results Guide Treatment
Results feed directly into management. In acute leukemia, the blast percentage, immunophenotype, and genetic findings determine the subtype, risk group, chemotherapy regimen, and whether hematopoietic stem cell transplantation (HSCT) should be considered. In MDS, specific mutations and cytogenetic changes help define prognosis and can point to targeted therapies. In myeloma, the percentage of plasma cells supports diagnosis. Repeat biopsies after treatment check for remission and measurable residual disease.
Genomic testing has expanded what a single sample can reveal. Blood-based tests, sometimes called liquid biopsies, are being studied for monitoring certain conditions, but they do not yet replace examination of the bone marrow itself for diagnosis.
Key Takeaways
- Bone marrow biopsies combine an aspirate and a core to assess both cells and marrow architecture.
- Indications include unexplained cytopenias, suspected blood cancers, staging, and treatment monitoring in patients with hematological disorders.
- The posterior iliac crest is the standard site, and the procedure takes about half an hour under local anesthetic.
- Serious complications are uncommon, and aftercare is simple.
- Morphology, flow cytometry, cytogenetics, and molecular tests together drive diagnosis and treatment.
Frequently Asked Questions
Does a bone marrow biopsy hurt?
Local anesthetic numbs the skin and bone surface, but most people feel pressure and a brief, deep pulling pain during aspiration. Soreness for a few days afterward is common and usually settles with simple painkillers.
How long do bone marrow biopsy results take?
Initial smear findings can be available within a day or two. The core needs decalcification, and cytogenetic and molecular tests can take one to two weeks or longer.
Can I drive home after a bone marrow biopsy?
If you had only local anesthetic, many centers allow it, although having someone with you is wise. If you received sedation, you should not drive for the rest of the day.
Why is the hip bone used?
The posterior iliac crest lies close to the skin, contains active red marrow throughout adult life, and is away from major blood vessels and organs. That makes it the safest and most productive site for both aspirate and core.
