The procedure described by CPT code 38222 involves the concurrent performance of both a diagnostic bone marrow biopsy and a bone marrow aspiration, typically performed through the same incision on the same bone, which is most commonly the posterior superior iliac crest, but occasionally the sternum or anterior iliac crest. Bone marrow is the spongy tissue found inside bones that houses stem cells responsible for producing red blood cells, white blood cells, and platelets. The primary purpose of this dual procedure is to obtain both liquid marrow via aspiration for cytological, flow cytometric, and molecular evaluation, and a solid core of bone marrow tissue via biopsy to assess overall marrow architecture, cellularity, and the presence of focal lesions, fibrosis, or metastatic infiltration. The physician begins by positioning the patient appropriately, usually in a prone or lateral decubitus position to expose the pelvic area. The overlying skin is prepped with an antiseptic solution and draped in a sterile fashion to maintain a completely sterile field. Local anesthesia, such as lidocaine, is meticulously infiltrated into the skin, subcutaneous tissue, and down to the periosteum of the target bone to ensure maximum patient comfort. Occasionally, conscious sedation or mild systemic analgesia is also utilized depending on patient tolerance and clinical setting. For the aspiration portion of the procedure, a specialized bone marrow aspiration needle equipped with a stylet is advanced with steady pressure through the tough outer cortex and into the medullary cavity. The stylet is then removed, a sterile syringe is attached, and rapid negative pressure is applied to aspirate the liquid marrow contents. Multiple aspirations may be performed using different syringes to gather adequate samples for diverse laboratory tests. Following the aspiration, or sometimes prior depending on the exact procedural sequence preferred by the physician, the core biopsy is performed. A Jamshidi or similar specialized biopsy needle is inserted, typically through the exact same skin incision but angled slightly differently to penetrate and sample a completely fresh, undisturbed area of the marrow cavity. The biopsy needle is firmly advanced with a twisting, alternating motion to cut and capture a solid cylindrical core of intact bone and marrow. Once an adequate specimen is deemed captured, the needle is gently rocked side to side to detach the core from the underlying host bone, and it is subsequently withdrawn. The core biopsy specimen is carefully pushed out of the needle using a probe into a collection container filled with a fixative solution. Firm manual pressure is immediately applied to the puncture site for several minutes until complete hemostasis is achieved, followed by the application of a tight, sterile pressure dressing. Post-procedure, the patient is closely monitored for any signs of hemorrhage, hematoma formation, or localized infection. This comprehensive code captures the dual evaluation provided when both of these highly critical sampling techniques are executed together, offering a robust and complete diagnostic picture for complex hematologic and oncologic conditions. The precise retrieval of these respective specimens is imperative for the accurate diagnosis, subclassification, and staging of disorders such as acute and chronic leukemias, various lymphomas, multiple myeloma, and myelodysplastic syndromes. Performing this dual procedure requires intricate anatomical knowledge and clinical expertise to ensure a high diagnostic yield while simultaneously minimizing patient discomfort and potential procedural complications.