bone marrow biopsy are carry out principally to permit cytological assessment of bone marrow cell . however , in some clinical circumstance other test-for example , cytogenic and immunophenotypic analysis-are equally importance. In many patient ,a trephine biopsy will be carry out as part often same procedure. b should be preceded by evaluation of the medical history and clinical features,examination of blood film and assessment of results of full bloodcount, other lanoratory test ,and radiological investigation . this is essential to ensure that all appropriate tests are performed on the material obtained and to permit an adequate evaluation