There are two types of bone marrow aspirations. If the purpose is to diagnose a hematologic disease or to determine the effectiveness of treatment for a hematologic disease, the bone marrow can be aspirated from the anterior superior iliac spine, posterior superior iliac spine, or sternum, and then the aspirated bone marrow can be examined to diagnose the disease or determine the effectiveness of treatment. In the case of bone marrow transplantation, the amount of blood stem cells required is often too large to be performed by simple bone marrow aspiration. The patient is usually given a subcutaneous injection of granulocyte colony-stimulating factor to mobilize the hematopoietic stem cells from the bone marrow into the peripheral blood. Once the number of hematopoietic stem cells in the peripheral blood reaches a certain level, a blood cell separator can be used to separate the hematopoietic stem cells from the circulation of the body through a vein and store them for use in a bone marrow transplant. So where the bone marrow is drawn needs to be determined by the specific needs.