Maximum diagnostic information is obtained when peripheral blood smears, bone marrow aspiration smears, trephine biopsy imprints, trephine and clot biopsy sections are simultaneously examined. Peripheral blood smears reflect end organ function and provide clues to underlying hematolymphoid pathology that may prompt additional studies including bone marrow examination. Bone marrow aspiration alone has diagnostic utility in the evaluation of a limited number of primary hematological conditions including: megaloblastic anemias, hyporegenerative anemias, certain hemolytic anemias, normochromic normocytic anemias, neutropenias, thrombocytopenias, immunoglobulin disorders, storage diseases, and leukemias (Bain, J Clin Pathol 54:657–663, 2001). Bone marrow trephine biopsy is indicated in those situations where marrow aspiration is unsuccessful; in evaluation of cytopenias, myelofibrosis, suspicion of lymphoma, metastatic tumor, granulomatous disease, evaluation of myeloproliferative neoplasms, and for the examination of trabecular bone in metabolic diseases (Bain, J Clin Pathol 54:737–742, 2001). Many of the indications for marrow aspiration overlap with those for trephine biopsy. Because it is not possible to predict which patients will have diagnostic aspiration biopsies and which will have diagnostic trephine biopsies, both procedures are routinely performed together (Brynes et al., Am J Clin Pathol 70:753–759, 1978; Cotelingam, Adv Anat Pathol 10:8–26, 2003; Lee et al., Int J Lab Hematol 30:349–364, 2008; Peterson et al., Arch Pathol Lab Med 126:1050–1056, 2002).