Peripheral blood admixture in bone marrow aspirates.

A simple method is described by which the degree to which a bone marrow aspirate is diluted with peripheral blood, the admixture of peripheral blood leukocytes in the aspirate, and the true cellularity of bone marrow at the aspiration site can be estimated quantitatively. A highly significant correlation is shown to exist between the true bone marrow cellularity and the number of hemopoietic cells in the bone marrow aspirate. This correlation can be described by an exponential regression equation (r = 0.6997; p less than or equal to 0.001). The degree of bone marrow dilution with peripheral blood does not depend on the initial bone marrow cellularity and is devoid of diagnostic value. It fluctuates over a wide range (1.2- to 6.3-fold). The admixture of peripheral blood leukocytes has been found to be small (0.05%-9.7%) in most cases studied and much higher in those cases where the cellularity is low while the dilution is high.