Impaired megakaryocyte maturation is often considered a typical change on bone marrow examination in idiopathic thrombocytopenic purpura (ITP). In clinical workup, it is found that diseases such as connective tissue disease, hypersplenism, and megaloblastic anemia can also present with peripheral thrombocytopenia and impaired bone marrow megakaryocyte maturation. Diagnostic criteria for impaired maturation of bone marrow megakaryocytes: 1. multiple laboratory tests for thrombocytopenia; 2. no or only mildly enlarged spleen; 3. increased or normal megakaryocytes on bone marrow examination with impaired maturation; 4. any one of the following five items: ① effective prednisone treatment; ② effective splenectomy treatment; ③ increased PAIgG; ④ increased PAC3; ⑤ shortened platelet lifespan measurement.