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1'_ 1S a dia g nostic aid in pediatric hematology, the validity of single-site examinations as compared with multiple sites has been questioned in the past and again recently., To determine whether the bone marrow reacts as a unit to disease processes involving it, or whether there are significant intra-individual variations in the cellular content of marrows obtained from two corresponding body sites, we performed simultaneous dual-site bone marrow aspirations 53 times on 48 children consecutively examined at the Medical University of South Carolina Hospital who had clinical or laboratory findings confirming or suggesting the presence of hematologic disease. These children ranged in age from 7 days to 12 years. Eighteen were females; 30 were males.
MethodsAll bone marrow aspirations were done using an 18 gauge Osgood needle, and 0.1 cc to 0.2 cc of marrow transferred to clean slides. The marrow was allowed to spread in the angle formed by two slides. The top slide was then moved over the horizontal slide effecting the spread of the marrow. The slides were dried. Wright's stain was applied. 200 nucleated cells from each aspiration specimen were counted under oil immersion by the same technologist. An AO Microstar binocular Series 10 microscope was used.A chi-square test of independence of proportions of cell types from the two locations sampled was then calculated for each of the cases. The statistical analysis of these counts was carried out on an IBM 360 Model 40 Computer. A significant chisquare would indicate that the proportions of cell types differ between locations.
ResultsWith 49 of the 53 dual-site aspirations, it could not be concluded that the proportions of cell types differed between locations. Each chi-square was checked for significance at the 5% level. If there were no true differences in proportions of cell types between locations, one would expect that 2.65 out of the 53 chisquares would be statistically significant due to random fluctuations in sampling. Since the chi-squares were independent, it was possible to calculate that at least 5 individual chi-squares would have to be significant in order to conclude that the true proportions of cell types differed between locations for any individual.Only 4 were observed. It is concluded that the true proportions of cell types between locations within the individuals do not differ.
Discussion
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