it is characterized by : ( 1 ) clinical signs of thrombocytopenia , such as hemorrhages into the skin and tissues and from body orifices , ( 2 ) coagulation defects related to thrombocytopenia , such as prolonged bleeding time and poor clot retraction , ( 3 ) hematologic changes such as severe to moderate thrombocytopenia , often blood loss anemia , and signs of increased erythropoiesis , and ( 4 ) an absence or decreased number of megakaryocytes in the bone marrow during early phase and increased number during compensatory phase .
C0025166
megakaryocytes
C0005953
bone marrow