There are two main causes of low bone marrow, as follows: First, it is related to the operation, such as the failure of the operation when doing bone puncture, or due to the inhalation of more blood during the puncture process, or the incomplete aspiration of the bone marrow tissue during the puncture process. Second, the operation is correct, there are indeed bone marrow diseases, such as aplastic anemia, or fibrosis of the bone marrow, eventually causing a reduction in the bone marrow itself, aplastic anemia or myelofibrosis and other blood diseases, the etiology is more complex, especially aplastic anemia, generally with exposure to radioactive substances or toxic chemicals, and drugs caused by myelofibrosis clinical The etiology of myelofibrosis is not clear.