Hematology

What Happens During a Bone Marrow Biopsy for Myelofibrosis?

At a Glance

During a bone marrow biopsy for myelofibrosis, the area is numbed and a clinician collects liquid marrow and a small bone core from the pelvic bone. Scarring may prevent liquid collection (a “dry tap”), but the core can still provide essential information, and results arrive in stages.

A bone marrow biopsy is an important procedure used to help confirm a diagnosis of myelofibrosis and, in certain situations, reassess the disease if your symptoms or blood counts change ^[1]. During the procedure, a doctor or specially trained nurse removes a small sample of liquid bone marrow (aspiration) and a solid piece of spongy bone (core biopsy) from the back of your pelvic bone ^[2]. While the area is numbed with a local anesthetic, you can expect to feel pressure and a brief, sharp pain or cramping sensation when the samples are withdrawn. Because the samples undergo different types of testing, your results will arrive in stages over several days to a few weeks ^[2]^[3].

Preparing for the Procedure

Before your biopsy, your care team will review your medications and your most recent blood counts. Because myelofibrosis can affect your platelet levels and blood clotting, it is especially important that your doctor knows if you are taking any blood thinners, anticoagulants, aspirin, or supplements. Do not stop taking these medications without specific instructions from your prescribing doctor ^[4]^[5].

If you are feeling anxious about the procedure, tell your medical team. Anxiety can affect how you experience pain, and it is entirely okay to ask the clinician to explain each step, pause, or provide more local anesthetic if needed ^[6]^[7]. Some centers may offer a mild sedative to help you relax if arranged in advance ^[8]. If you will be receiving a sedative, you must follow your clinic’s specific rules, which usually include fasting beforehand, having a responsible adult drive you home, and avoiding driving or making important decisions for the rest of the day.

During the Procedure

For the procedure, you will typically be asked to lie comfortably on your side or stomach so the clinician can easily access the back of your pelvic bone (not the hip joint), an area known as the posterior iliac crest ^[9].

The doctor will clean the skin and inject a local anesthetic (like lidocaine) to numb the area ^[10]. This injection may sting for a moment. Once the area is numb, the doctor inserts a special hollow needle into the bone. You will likely feel strong pressure as the needle goes in. When the liquid marrow is pulled out (aspirated), some people feel a brief, sharp pain or pressure, sometimes radiating down their leg or hip ^[10].

Note on “Dry Taps”: Because myelofibrosis involves scar tissue in the marrow space, it is very common for the doctor to be unable to draw out any liquid—a situation called a “dry tap.” This does not mean the procedure failed or that your disease has worsened; the solid core biopsy can still provide the essential information needed for your report ^[11]^[12].

After the liquid is attempted, a needle is used to capture a small, solid core of bone, which can also cause a deep, brief ache or pressure.

Recovery, Wound Care, and Warning Signs

After the needle is removed, a pressure bandage or compression dressing will be applied to the site ^[13]. You may be asked to lie flat on your back or remain under observation for a short time, depending on your clinic’s protocol and whether you received sedation ^[14].

It is normal to have some soreness, achiness, and bruising at the biopsy site for a few days ^[15]. You can usually manage this with ice packs and pain relievers approved by your doctor ^[14]. Do not take aspirin or NSAIDs (like ibuprofen or naproxen) without asking your doctor first, as these can increase your risk of bleeding. Ask if acetaminophen is safe for you instead.

Before you leave, your care team will give you instructions on when you can safely shower, when to remove the bandage, and how long to avoid heavy lifting or strenuous activity.

While severe complications are rare, you should know what to watch for. If the site starts bleeding, immediately apply firm, uninterrupted direct pressure. Contact your care team immediately or go to the nearest emergency room if you experience:

Bleeding that does not stop with pressure, or soaks through the bandage ^[16]
Dizziness, severe weakness, or fainting (syncope) ^[16]^[17]
A fever (ask your clinic for their specific temperature threshold, often 100.4°F or 38°C) ^[18]
Increasing pain, swelling, or redness at the biopsy site ^[18]
Pus or drainage coming from the wound ^[19]
Difficulty walking ^[18]^[19]

Understanding Your Pathology Report

Your bone marrow samples are analyzed by a hematopathologist. Because different tests take different amounts of time, your results will be reported in stages ^[2]^[3]. Your hematologist will combine these biopsy results with your blood counts, symptoms, and spleen size to understand your overall health.

A complete myelofibrosis pathology report will evaluate several specific factors:

Cellularity: This measures how much of your marrow space is filled with blood-forming cells versus fat. In early myelofibrosis, the marrow is often packed with cells (hypercellular) ^[20]. In advanced disease, it can sometimes become depleted of cells ^[21].
Megakaryocyte Morphology: Megakaryocytes are the cells that make platelets. In myelofibrosis, these cells look abnormal (atypical) under a microscope and tend to cluster together ^[20]^[22].
Fibrosis Grade: This tells you how much scarring is in the bone marrow. The pathologist uses a silver stain to measure reticulin (an early, web-like scar tissue) on a scale from 0 to 3 ^[23]. Grades 0 to 1 describe “prefibrotic” or early marrow changes, while grades 2 to 3 describe overt fibrotic marrow ^[24]^[25]. A trichrome stain is used to check for thicker scarring called collagen ^[23]. Note that the fibrosis grade describes the marrow’s appearance, but it does not determine your overall prognosis on its own.
Blasts: Blasts are immature blood cells. A healthy marrow has very few blasts. If the percentage of blasts increases over time, your doctor will monitor this closely alongside your blood tests, as it can be a sign of disease progression ^[26]^[27].
Cytogenetics: This looks at the chromosomes inside your marrow cells (using a test called a karyotype) to find large genetic changes ^[28]^[29].
Molecular Tests: These look for specific DNA mutations. The report may note if you have a “driver” mutation (JAK2, CALR, or MPL) that strongly supports the diagnosis of myelofibrosis ^[28]^[30]. However, some people are negative for all three. The lab may also check for additional high-molecular-risk mutations (like ASXL1 or EZH2) which help your doctor calculate your personal risk score and prognosis ^[27]^[31].

Common questions in this guide

What is done during a bone marrow biopsy for myelofibrosis?

You will usually lie on your side or stomach while the clinician numbs the skin over the back of your pelvic bone. A needle is used to try to remove liquid marrow and then a small solid bone core. Pressure and a brief sharp pain or cramping can occur, especially when the samples are withdrawn.

What does a dry tap mean in myelofibrosis?

A dry tap means the clinician cannot draw out liquid marrow, often because scarring has made the marrow space less able to yield fluid. It does not by itself mean the biopsy failed or that myelofibrosis has worsened, because the solid core can still be examined.

How should I prepare for a myelofibrosis bone marrow biopsy?

Tell your care team about every medication and supplement you take, especially blood thinners, aspirin, and anti-inflammatory pain relievers. Do not stop or change a medication unless the prescribing clinician gives you instructions. If sedation is planned, ask about fasting and arrange for a responsible adult to drive you home.

Will a bone marrow biopsy for myelofibrosis hurt?

The skin and tissue are numbed with a local anesthetic, although the injection may briefly sting. Pressure is common, and some people feel a short sharp pain or cramping when marrow is withdrawn. Tell the clinician if you are anxious or uncomfortable so they can pause, provide more anesthetic, or discuss sedation when available.

What warning signs should I watch for after a bone marrow biopsy?

Soreness, achiness, and bruising for a few days are common. Apply firm, continuous pressure if the site bleeds, and contact your care team urgently or seek emergency care for bleeding that will not stop, fainting or severe weakness, fever, increasing pain or redness, drainage, or difficulty walking.

When will my myelofibrosis biopsy results be ready, and what will they show?

Results often arrive in stages over several days to a few weeks because the samples require different tests. The report may assess marrow cellularity, megakaryocytes, fibrosis, blasts, chromosomes, and gene mutations. Your hematologist will interpret these findings together with your blood counts, symptoms, and spleen size.

Key takeaways

A myelofibrosis bone marrow biopsy usually includes an attempt to collect liquid marrow and a solid core from the back of the pelvic bone using local anesthetic.
Scarring can cause a dry tap, but this does not by itself mean the procedure failed or that myelofibrosis has worsened because the solid core can still be analyzed.
Tell your care team about blood thinners, aspirin, anti-inflammatory pain relievers, and supplements, and do not change medications without instructions.
Mild soreness and bruising are common after the biopsy, but persistent bleeding, fever, worsening pain or redness, drainage, fainting, or difficulty walking requires prompt medical attention.
The pathology report may assess cellularity, megakaryocytes, fibrosis, blasts, chromosomes, and mutations, with results often arriving over several days to a few weeks.

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This page explains what to expect from a bone marrow biopsy for myelofibrosis for educational purposes and does not replace medical advice. Follow your hematology team's instructions about medications, sedation, wound care, and warning signs.