Bone marrow examination is useful in the diagnosis and staging of hematologic disease, as well as in the assessment of overall bone marrow cellularity. Because of easy accessibility, aspiration, biopsy, and culture of the bone marrow may also play a role in the assessment of patients with fever of undetermined origin as well as in the diagnosis of various storage and infiltrative disorders.
The indications, contraindications, technique, and complications of bone marrow aspiration and biopsy will be reviewed here . Evaluation of bone marrow aspirates and biopsies is presented separately. (See "Evaluation of bone marrow aspirate smears".)
The bone marrow is one of the most widely distributed organs in the human body. It is the principal site of blood formation beginning at the time of birth, at which time all bone cavities are filled with hematopoietic tissue. (See "Overview of hematopoiesis and stem cell function", section on 'Bone marrow anatomy and microenvironment'.)
By adolescence, active marrow is usually only found in the cavities of axial bones (sternum, ribs, vertebrae, clavicles, scapulae, skull, pelvis, and the proximal ends of the femurs and humeri) (image 1) [2,3]. Overall bone marrow cellularity approximates 100 percent at birth and declines with time, paralleling an age-associated reduction in hematopoietic activity. Accordingly, bone marrow cellularity in the normal adult is approximately 50 percent, with the remainder of the marrow being composed of adipose tissue (picture 1). (See "Evaluation of bone marrow aspirate smears", section on 'Estimation of cellularity and myeloid to erythroid ratio'.)
Under physiologic conditions, all sites of hematopoiesis tend to exhibit uniform cellularity and cell lineage proportions. Thus, generalizations can be made regarding overall hematopoiesis from the evaluation of bone marrow at a single site. In most hematologic disorders, study of bone marrow at multiple sites has not been shown to improve diagnostic accuracy . Exceptions include malignancies which may have patchy marrow involvement (eg, multiple myeloma, lymphoma, metastatic disease), requiring either larger specimens or specimens from multiple sites (see 'Adequacy of the biopsy specimen' below).