Pathophysiology 

Normally the platelets are formed from megakaryocytes (stem cells) in the.  bone marrow. These cells mature, fragment and are released in  the blood stream. In idiopathic thrombocytopenic purpura  there  is rapid platelet  destruction beacuse of presence of platelet antibodies which results  in bleeding. There is no  failure to produce platelets as there are abundant platelet precursors (megakaryocytes)  in the bone marrow. 

Assessment 

The child may present with petechiae ecchymosis, bleeding of the gums and epistaxis. Bleeding in  the skin may be seen prominently over the legs. There may be hematemesis, malena, haematuria and haemarthrosis which indicate  internal haemorrhage. There may also be occasional low grade fever. Anaemia may be present  if there  is significant  blood loss. Diagnostic evaluation includes laboratory examination of blood which reveals platelet  count below  (40,000) 20,000/mm³ other platelet function tests  such as tourniquet test, bleeding time and clot retraction is abnormal. The white blood cell count and cloting time  is normal.