Synopsis
Select bone-marrow aspiration, trephine biopsy and ancillary studies for a defined clinical question, prepare the patient safely and translate morphology, flow and genetics into a coherent diagnosis.
- Define the question before the procedure: unexplained cytopenia, suspected acute leukaemia, myelodysplasia, marrow infiltration, plasma-cell disorder, lymphoma staging, fibrosis, storage disease or fever of unknown cause each needs different samples.
- Aspiration provides individual-cell morphology, differential counts, flow cytometry, cytogenetics, molecular tests and microbiology; the trephine preserves architecture, cellularity, fibrosis, focal infiltrates and spatial relationships.
- Most adult samples come from the posterior iliac crest. Sternal aspiration is an expert-only alternative in selected circumstances and cannot provide a trephine; the sternum is not used for routine biopsy.
Key red flags
Blasts, abnormal promyelocytes, rapidly worsening cytopenias, infection, bleeding or leukostasis symptoms require urgent blood and marrow classification within an emergency haematology pathway.
Investigation priorities
Confirm the indication and plan bleeding-risk mitigation before an invasive sample.
Management branches
Persistent blood, clinical or imaging abnormalities raise a marrow diagnosis but immediate instability has been addressed.
- Review peripheral film, reticulocytes, haematinics, haemolysis, renal, liver, infection, imaging and medicine causes first, documenting the unresolved question that marrow should answer.
- The preferred plan is combined aspirate and trephine when cellularity, architecture or infiltration matters; aspiration alone is an alternative only when the specific question is cytological and the core would not add value.
Key medicines
Lidocaine 1% local anaestheticInfiltrate skin, subcutaneous tissue and periosteum incrementally, aspirating before injection, using the smallest effective volume and staying below 3 mg/kg and 200 mg total without adrenaline.