A bone marrow biopsy and aspiration is a short outpatient procedure, usually done at the back of the hip bone (the posterior iliac crest). After numbing the area, a doctor uses one needle to draw out liquid marrow (the aspiration) and then takes a small solid core of bone and marrow (the biopsy). Needle time is usually about 10 minutes, and the whole visit takes 20 to 30 minutes plus recovery. Most people go home the same day with a small bandage and some soreness for several days.
These tests are central to diagnosing hematologic disorders, and they give information that no blood test can. Below I walk through what happens before, during and after, in the order you will experience it, and answer the questions my patients ask most.
Aspiration vs Biopsy: Two Samples, One Visit
People use one name for both, but they are two separate samples that answer different questions. Both are usually taken through the same small skin puncture. Bone marrow aspiration withdraws a few milliliters of liquid marrow, a bit like drawing blood from inside the bone. The biopsy removes a thin core of bone and marrow, usually around 1.5 to 2 cm long, which keeps the marrow’s structure intact.
| Feature | Aspiration | Biopsy (trephine) |
|---|---|---|
| Sample | Liquid marrow | Solid core of bone and marrow |
| What it shows | Individual cells: their appearance, counts, blast percentage, iron stores | Architecture: how full the marrow is (cellularity), scarring (fibrosis), infiltration by abnormal cells |
| Extra tests | Flow cytometry, chromosome studies (cytogenetics), FISH, molecular testing | Immunohistochemistry, reticulin stain for fibrosis |
| What it feels like | A brief, deep pulling or cramping sensation lasting a few seconds | Pressure and pushing, sometimes a dull ache |
| When it can fail | “Dry tap”, no liquid obtained (for example in myelofibrosis) | Rarely, if the core is too short or crushed |
Why Your Doctor Might Order It
A marrow test is rarely the first test. It usually follows blood work that simpler tests can’t explain. Common reasons include:
- Unexplained low counts (cytopenias): low red cells, white cells or platelets without a clear cause
- Suspected leukemia or myelodysplastic syndrome, especially if immature cells (blasts) appear on a blood smear
- Multiple myeloma and related plasma-cell disorders
- Lymphoma staging: checking whether it has reached the marrow
- Unexplained high counts, suggesting a myeloproliferative neoplasm
- Fever of unknown origin, when marrow infections such as tuberculosis are possible
- Checking treatment response, for example whether leukemia has cleared after chemotherapy
A referral does not mean cancer is expected. Many marrow tests are done to rule problems out, or to explain abnormal blood results that turn out to be benign.
Before the Procedure: Preparation
Blood thinners and other medicines
Tell your care team about every medicine and supplement you take, especially anything that affects bleeding:
- Anticoagulants such as warfarin, apixaban, rivaroxaban, dabigatran, edoxaban, heparin or enoxaparin
- Antiplatelet drugs such as aspirin, clopidogrel, prasugrel or ticagrelor
- NSAIDs such as ibuprofen or naproxen
- Supplements that can affect bleeding, such as fish oil or vitamin E
Do not stop a blood thinner on your own. Many are prescribed to prevent strokes or clots, and stopping them carries its own risks. The doctor who prescribed it and the team doing the biopsy will decide together whether to pause it, for how long, and whether you need a temporary substitute. Your team will usually check a recent blood count and, if needed, a coagulation panel (PT/INR and aPTT).
Eating, driving and practical steps
- With local anesthetic alone, you can usually eat normally and drive yourself home.
- If you are having sedation or general anesthesia, you will get fasting instructions and must arrange an adult to take you home.
- Wear loose, comfortable clothing, and bring a list of your medicines.
- Mention any allergies, especially to local anesthetics, latex, antiseptics or tape.
Questions to ask your care team beforehand
- Why is this test being done, and what are you looking for?
- Which site will you use, and will you take both an aspirate and a biopsy?
- What pain relief or sedation is available to me?
- Do I need to change any of my medicines, and when do I restart them?
- Can I drive home, and can I go to work the next day?
- When will results be ready, and who will explain them?
Numbing, Sedation and Anesthesia Options
Pain control is on a spectrum. What you are offered depends on your age, anxiety, medical history and the center’s practice:
| Option | What it involves | Awake? | Who gets it |
|---|---|---|---|
| Local anesthetic only | Lidocaine injected into the skin and the bone’s outer lining (periosteum) | Yes, fully | Most adults |
| Oral anti-anxiety medicine | A tablet such as lorazepam before the procedure, plus local anesthetic | Yes, relaxed | Adults who are anxious |
| Moderate (conscious) sedation | IV medicines such as midazolam and fentanyl, plus local anesthetic | Drowsy, may not remember | Adults who want more comfort or have found it painful before |
| Deep sedation or general anesthesia | Given by an anesthesia team | No | Most children; some adults with special needs |
If you want to be asleep or sedated, ask early. It needs to be arranged in advance and changes the fasting and transport rules.
During the Procedure: Step by Step
If you picture your lower back: the posterior iliac crest is the bony ridge you can feel on either side, just above the buttock, a few finger-widths from the spine. That is where the needle goes in most adults. The front of the hip bone, or rarely the breastbone (aspiration only), may be used instead.
- Check-in and consent. The doctor explains the procedure and risks and you sign a consent form. Your blood pressure and pulse are checked.
- Positioning. You lie on your side with knees drawn up, or on your stomach.
- Cleaning. The skin over the hip is cleaned with antiseptic, which feels cold, and covered with a sterile drape.
- Numbing. Local anesthetic is injected into the skin and then down to the surface of the bone. You’ll feel a sting and burning for a few seconds; the deeper injection onto the bone is the one most people notice.
- Aspiration. A hollow needle is pushed through the outer bone into the marrow, and a syringe pulls out liquid marrow. This causes the characteristic brief, deep pulling or cramping pain, sometimes running down the leg, for a few seconds.
- Biopsy. A slightly larger needle is advanced with a twisting motion to cut a small core. You will feel pressure and pushing; the needle is then rocked to free the core and withdrawn.
- Pressure and dressing. Firm pressure is applied to the site for a few minutes, then a pressure bandage goes on.
- Rest. You rest, often lying on your back to press on the site, for about 10 to 15 minutes, or longer after sedation, before going home.
Is It Painful? How Pain Is Reduced
Most people describe it as uncomfortable rather than severe. The numbing injection stings briefly. The aspiration pull is the sharpest moment, but it lasts only seconds, and the biopsy mostly feels like pressure. Local anesthetic cannot numb the marrow itself, which is why the aspiration pull is felt even when the skin and bone surface are fully numb.
Things that help:
- Ask for enough time after the local injection for it to work fully.
- Request an anti-anxiety tablet or IV sedation if you are nervous or have found it painful before.
- Slow, steady breathing and staying still help the procedure go quickly.
- An experienced operator makes a real difference. Don’t hesitate to ask how often the team does them.
Bone Marrow Biopsy in Children
Children almost always have their marrow test under general anesthesia or deep sedation, so they are asleep and don’t feel or remember it. The procedure itself is the same, usually from the back of the hip bone, and often combined with other procedures such as a lumbar puncture to limit anesthesia episodes. Children need to fast beforehand and recover in a monitored area until fully awake. Most can go back to normal play, school and activities after about 24 hours, avoiding swimming and baths until the site has healed a little.
After the Procedure: Home Aftercare
- Bandage: keep it on, clean and dry for 24 hours.
- Showering: you can usually shower after 24 hours. Avoid baths, hot tubs and swimming until the site has closed, usually a few days.
- Bleeding: a little oozing is normal. If the bandage becomes soaked, press firmly on the site with clean gauze for 10 minutes. If bleeding continues, call your team.
- Pain relief: acetaminophen (paracetamol) is usually enough. Avoid aspirin and NSAIDs such as ibuprofen for 24 hours unless your team says otherwise, because they can increase bleeding.
- Blood thinners: restart only as your care team instructed.
- Activity: avoid heavy lifting and strenuous exercise for about 24 hours. After sedation, don’t drive, drink alcohol or sign important documents for 24 hours.
Recovery timeline
| Time after procedure | What to expect |
|---|---|
| First 10–15 minutes | Rest with pressure on the site (longer after sedation) |
| Same day | Home; soreness as the anesthetic wears off |
| 24 hours | Remove the bandage and shower; resume most normal activities |
| 2–7 days | Aching or bruising at the site that steadily improves; usually gone within about a week |
| A few days to a few weeks | Results arrive in stages (see below) |
When to Call Your Doctor
Contact your care team promptly if you have any of these:
- Fever of 100.4°F (38°C) or higher, or shaking chills
- Bleeding that soaks the bandage and does not stop with 10 minutes of firm pressure
- Increasing redness, warmth, swelling or pus at the site
- Pain that gets worse instead of better, or is not controlled by acetaminophen
- New leg pain, numbness or tingling on the biopsy side
- Dizziness, fainting or a rapid heartbeat
If you have a low white cell count or are on chemotherapy, treat any fever as urgent and follow the fever instructions your team has given you.
Results and What Doctors Look For
Results come back in stages. The basic microscope report often takes a few days. Flow cytometry is often back within a week. Chromosome, FISH and molecular tests can take one to three weeks. Your hematologist usually discusses the first findings and updates you as the rest arrive.
- Cellularity: the share of marrow space filled with blood-forming cells. As a rule of thumb it is roughly 100 minus your age, as a percentage.
- Blast percentage: normally under 5%. A count of 20% or more generally defines acute leukemia.
- Balance and maturation of the red-cell, white-cell and platelet-forming lines
- Fibrosis: graded on a reticulin stain, key in myelofibrosis
- Iron stores: shown on an iron stain of the aspirate
- Genetic studies: chromosome changes and gene mutations that guide diagnosis and treatment
Risks
Bone marrow biopsy is a very safe procedure. The most common problems are soreness and bruising. Bleeding is uncommon and more likely with very low platelets or blood thinners, which is why your team reviews both first. Infection is rare with sterile technique. Serious bleeding into the deep tissues around the pelvis is very rare. Your hematologist weighs these small risks against what the test can reveal, as with any procedure in hematology.
Frequently Asked Questions
Is a bone marrow biopsy painful, and how can pain be reduced?
Expect brief stinging from the numbing injection, a few seconds of deep pulling pain during aspiration, and pressure during the biopsy. Good local anesthetic, an anti-anxiety tablet or IV sedation all reduce it; ask about these in advance.
Can I be put to sleep for a bone marrow biopsy?
Often, yes. Children usually have general anesthesia, and many centers offer adults IV sedation or, in some cases, general anesthesia. It must be arranged ahead of time, and you will need to fast and have someone take you home.
Should I stop blood thinners before a bone marrow biopsy?
Only if your care team tells you to. Some blood thinners are paused for a set number of days and some are continued. The plan depends on the drug and on why you take it, so never stop one on your own.
When can I shower after a bone marrow biopsy?
Keep the bandage dry for 24 hours, then shower normally. Avoid baths, hot tubs and swimming for a few days until the site has closed.
How long will I be sore afterwards?
Most people have aching or bruising for a few days, and it is usually gone within about a week. Acetaminophen helps; pain that worsens should be reported.
What fever or symptoms mean I should call my doctor?
A temperature of 100.4°F (38°C) or higher, bleeding that won’t stop with 10 minutes of pressure, spreading redness or pus, worsening pain, or new leg numbness or weakness.
Does a bone marrow biopsy mean I have cancer?
No. It is also used to investigate anemia, low counts, infections and other non-cancerous conditions. It means your doctor needs more information than a blood test can give.
Key Takeaways
- Aspiration takes liquid marrow; biopsy takes a solid core. Both usually come from the back of the hip in one short visit.
- Don’t stop blood thinners unless your team tells you to, and discuss sedation early if you want it.
- Keep the bandage dry for 24 hours, avoid NSAIDs for 24 hours, and expect soreness for up to about a week.
- Call for a fever of 100.4°F (38°C) or higher, persistent bleeding, or new leg symptoms.
- Results arrive in stages over a few days to a few weeks.
For more on how marrow works and what these tests find, see our bone marrow guide.
