A bone marrow examination may be performed on patients over the age of 60 and people who do not respond to treatment, or when the diagnosis is in doubt. The bone marrow biopsy in ITP can show increased (thought not always) megakaryocytes, bizarre giant platelets and platelet fragments.  (Large platelets are often seen in the peripheral blood smear though this can be seen in other diseases.)  When the spleen is removed it may show increased lymphatic nodularity.
Idiopathic thrombocytopenic purpura other diagnostic studies
Glanzmann's thrombasthenia other diagnostic studies
Idiopathic thrombocytopenic purpura causes
Essential thrombocytosis other diagnostic studies
Glanzmann's thrombasthenia laboratory findings
Thrombotic thrombocytopenic purpura differential diagnosis
Glanzmann's thrombasthenia causes
Thrombotic thrombocytopenic purpura risk factors