A bone marrow biopsy (BMB) is a diagnostic procedure designed to evaluate the health and composition of the soft, spongy tissue found inside most large bones. This marrow produces the body’s red blood cells, white blood cells, and platelets. The procedure is typically ordered when blood tests show abnormal counts, such as unexplained anemia or elevated white blood cell levels. Examining a sample helps doctors diagnose a range of conditions, including blood disorders, leukemia, lymphoma, or determine if other cancers have spread to the bone. It may also be used to investigate the cause of an infection or monitor the effectiveness of treatment.
Preparing for the Biopsy
Before the procedure, the healthcare team will provide detailed instructions and obtain informed consent, which is a formal agreement where the patient confirms they understand the risks and benefits. A thorough review of all current medications and supplements is necessary, especially regarding blood-thinning agents like anticoagulants. Patients are often instructed to temporarily stop taking these specific medications before the biopsy to minimize the risk of bleeding at the site.
Patients can usually eat and drink normally beforehand, unless intravenous (IV) sedation is planned. If sedation is administered, fasting, often starting the night before, is required. Patients receiving sedation must arrange for someone to drive them home afterward, as the medication can cause drowsiness and impair their ability to operate a vehicle safely. Discussions with the provider will also cover pain management options, ranging from local anesthesia alone to a combination with light sedation.
The Steps of the Procedure
The bone marrow biopsy is typically performed in an outpatient setting, such as a clinic or hospital room, and usually takes about 10 to 20 minutes. The patient is positioned to allow easy access to the sampling site, which is most commonly the posterior iliac crest—the back of the hip bone. Positioning involves lying on the stomach or side, often with the knees possibly drawn up to the chest.
The area over the hip bone is first cleaned with an antiseptic solution and draped with sterile cloth. A local anesthetic, such as lidocaine, is then injected to numb the skin and the tissue down to the surface of the bone. Since the bone itself cannot be fully numbed, the provider ensures the periosteum—the highly sensitive membrane covering the bone—is adequately anesthetized, which may cause a brief stinging sensation as the medication is delivered.
The procedure involves two distinct parts, often performed through the same skin entry point: the bone marrow aspiration and the core biopsy. The aspiration is usually done first, using a specialized hollow needle inserted into the marrow cavity. A syringe is attached, and the provider quickly draws out a small amount of liquid bone marrow, which is the aspirate. This suction creates a brief, sharp pain or tugging sensation that is commonly reported as the most uncomfortable part of the procedure.
After the liquid sample is collected, the core biopsy is performed to obtain a solid piece of tissue. A larger, specialized needle is advanced into the bone, often with a twisting motion, to cut and capture a small core of the spongy bone and marrow. The patient may feel pressure or a dull, deep ache as the needle is rotated. Once the core sample is obtained, the needle is removed, and firm pressure is immediately applied to the site to stop bleeding.
Post-Procedure Care and Monitoring
Following the procedure, immediate care involves applying firm pressure to the biopsy site for several minutes until bleeding has stopped completely. Patients who received only local anesthesia are typically asked to lie on their back for about 10 to 15 minutes to maintain this pressure. A sterile dressing is then placed over the wound.
The provider gives specific instructions for site care, advising the patient to keep the dressing dry and in place for at least 24 hours. Showering is usually permitted after 24 hours, but soaking the area in a bathtub, hot tub, or swimming pool is discouraged for several days to reduce infection risk. Soreness or bruising at the site is common and can be managed with over-the-counter pain relievers like acetaminophen.
Avoid strenuous activities, heavy lifting, or exercise that strains the hip for 24 to 48 hours. Monitor the site for complications, such as excessive bleeding that soaks through the dressing, increasing redness or swelling, or a fever higher than 100°F within 48 hours. These symptoms warrant a prompt call to the healthcare team for further instructions.
What Happens to the Sample
Once collected, the bone marrow aspirate and core tissue are sent immediately to a specialized laboratory for analysis. The liquid aspirate is quickly smeared onto glass slides, allowing pathologists to assess the morphology—or appearance—of individual cells and perform cell counts. The aspirate also provides material for advanced testing, such as flow cytometry and cytogenetics, which analyze cell surface markers and chromosomes to identify abnormal cell populations.
The solid core biopsy provides a three-dimensional view of the marrow’s architecture and requires a different process. This sample is placed in a fixative solution, then embedded in paraffin wax, cut into very thin slices, and stained. This method allows the pathologist to evaluate the overall cellularity, the ratio of fat to blood-forming cells, and whether abnormal cells are present in clusters. While initial results from the aspirate smears may be available quickly, the comprehensive analysis, including specialized studies on the core biopsy, typically takes between one and three weeks to complete. The ordering physician communicates the final results and diagnosis to the patient.