Bone marrow examination is to obtain bone marrow fluid or intact bone marrow tissue through bone marrow aspiration or bone marrow biopsy for morphology, immunology, cytogenetics, molecular biology and other related examinations. Bone marrow aspiration is usually performed by taking the anterior superior iliac spine and posterior superior iliac spine of the patient as puncture points, routinely disinfecting the skin, anesthetizing with lidocaine, puncturing the bone marrow cavity with a puncture needle, and removing the bone marrow fluid for smear by dry injection. At the same time, another 5 ml of bone marrow fluid is extracted for various examinations. Through bone marrow aspiration examination, a clear diagnosis of most hematologic diseases can be made. However, in patients with aplastic anemia or myelofibrosis, the bone marrow fluid can often not be obtained by bone marrow aspiration, and it is necessary to obtain the complete bone marrow tissue through a bone marrow biopsy needle, and then pathological examination can confirm the diagnosis of aplastic anemia or myelofibrosis.