Bone marrow is a soft, spongy tissue found within larger bones that serves as the body’s primary factory for producing blood cells, including red blood cells, white blood cells, and platelets. An iliac crest bone marrow aspiration and biopsy collects a sample of this tissue for analysis. The procedure collects both the liquid portion (the aspirate) and a solid core of bone tissue (the biopsy), providing a comprehensive view of marrow structure and function. The iliac crest, the large, curved bone at the top of the pelvis, is the preferred site in adults due to its accessibility and safety.
Diagnostic Purposes of the Procedure
Doctors often order this test when routine blood work shows unexplained abnormalities in the number or appearance of circulating blood cells. The procedure is especially useful for investigating cytopenias (conditions involving too few blood cells), such as unexplained anemia, leukopenia, or thrombocytopenia. Examining the marrow helps determine if the underlying issue is a production problem within the bone factory itself or a peripheral problem outside of it.
The test is also fundamental in diagnosing and staging various cancers that affect the blood and bone marrow. These include acute and chronic leukemias, lymphomas, and multiple myeloma. A bone marrow exam can also monitor treatment effectiveness by showing whether the marrow is recovering and producing healthy cells. It also helps in evaluating myelodysplastic syndromes, where blood cells fail to mature properly, and conditions like myelofibrosis, which involves the replacement of marrow with scar tissue.
Patient Preparation and Consent
Preparation begins with a thorough discussion between the patient and the medical team to obtain informed consent. This conversation covers the procedure details, potential risks, and expected sensations, which helps reduce patient anxiety. The healthcare provider reviews the patient’s medical history, paying particular attention to any history of bleeding disorders or allergies to local anesthetics.
Instructions regarding medications, especially blood thinners like aspirin or anticoagulants, are provided in advance. These medications may need to be temporarily stopped or adjusted to reduce bleeding risk. Patients may also be instructed to fast for a certain period before the procedure if sedation will be used. During the procedure, the patient is typically positioned lying on their stomach or side to allow easy access to the posterior superior iliac spine. If sedation is administered, arranging for a responsible adult to provide transportation home afterward is a necessary safety precaution.
The Aspiration and Biopsy Collection Process
Once positioned, the medical team prepares the site using a strict aseptic technique, cleaning the area with an antiseptic solution like povidone-iodine or chlorhexidine. A local anesthetic, commonly 1% lidocaine, is then injected into the skin, subcutaneous tissue, and down to the surface of the bone (the periosteum). This numbing minimizes pain, though the injection itself may cause a brief stinging or burning sensation.
The procedure involves two distinct parts, usually performed through the same small skin incision: the aspiration and the core biopsy. First, a specialized hollow needle is inserted into the marrow cavity. A syringe is attached to quickly withdraw a small sample of the liquid bone marrow, which is the aspiration. This suction often causes a sharp, brief, and sometimes painful sensation as the pressure inside the bone changes, indicating successful collection.
Immediately following aspiration, the needle is slightly repositioned. A second, larger needle is then used to collect a solid cylinder, or core, of bone tissue (the biopsy). This needle is advanced with a rotating motion until it captures a sample typically measuring 1.5 to 3 centimeters in length. While the bone itself cannot be fully numbed, patients generally feel significant pressure and a pushing or pulling sensation during the core biopsy part of the process. The specimen is then carefully removed from the needle and prepared for transport to the laboratory for detailed analysis.
Post-Procedure Monitoring and Care
Following sample collection, firm pressure is immediately applied to the puncture site for several minutes to stop any bleeding. A sterile bandage is then placed over the small wound. The patient is monitored for a short period, typically while lying down, to check for continued bleeding. Patients are advised to keep the dressing dry and in place for at least 24 hours to prevent infection.
For the next 24 to 48 hours, patients should avoid strenuous activity or heavy lifting that could strain the hip area. Mild soreness or bruising at the site is common and can usually be managed with over-the-counter pain relievers like acetaminophen. The medical team provides clear instructions on when to contact a physician. Warning signs include developing a fever over 100°F, experiencing severe pain not relieved by medication, or noting excessive bleeding, redness, or swelling at the site. While preliminary results may be available within a few days, specialized studies can sometimes take up to three weeks to be fully processed and discussed with the patient.