Clinical Manifestations. The infant with NATP is at risk for intracranial hemorrhage in utero and during the immediate delivery process. In ITP, the greatest risk seems to be present during passage through the birth canal, during which molding of the head may induce intracranial hemorrhage. Fetal scalp sampling or percutaneous umbilical blood sampling may be performed to measure the fetal platelet count.
Treatment. Administration of intravenous immunoglobulin (IVIG) before delivery increases fetal platelet counts and may alleviate thrombocytopenia in infants with NATP and ITP. Delivery by cesarean section is recommended to prevent central nervous system (CNS) bleeding (see Chapter 59). Neonates with severe thrombocytopenia (platelet counts <20,000/mm3) may be treated with IVIG or corticosteroids or both until thrombocytopenia remits. If necessary, infants with NATP may receive washed maternal platelets.
Etiology. Autoimmune thrombocytopenic purpura of childhood (childhood ITP) is a common disorder that usually follows an acute viral infection. Childhood ITP is caused by an antibody (IgG or IgM) that binds to the platelet membrane. The condition results in Fc receptor–mediated splenic destruction of antibody-coated platelets. Rarely, ITP may be the presenting symptom of an autoimmune disease, such as systemic lupus erythematosus (SLE).
Clinical Manifestations. Young children typically exhibit ITP 1 to 4 weeks after viral illness, with abrupt onset of petechiae, purpura, and epistaxis. The thrombocytopenia usually is severe. Significant adenopathy or hepatosplenomegaly is unusual, and the red blood cell (RBC) and white blood cell (WBC) counts are normal.
Diagnosis. The diagnosis of ITP usually is based on clinical presentation and the platelet count and does not often require a bone marrow examination. If atypical findings are noted, however, marrow examination is indicated to rule out an infiltrative disorder (leukemia) or an aplastic process (aplastic anemia). In ITP, an examination of the bone marrow reveals increased megakaryocytes and normal erythroid and myeloid elements.
Treatment and Prognosis. Therapy is seldom indicated for platelet counts greater than 30,000/mm3. Therapy does not affect the long-term outcome of ITP but is intended to increase the platelet count acutely. For moderate and severe clinical bleeding with severe thrombocytopenia (platelet count <10,000/mm3), therapeutic options include prednisone, 2 to 4 mg/kg/24 hours for 2 weeks or IVIG, 1 g/kg/24 hours for 1 to 2 days. All of these approaches seem to decrease the rate of clearance of sensitized platelets, rather than decreasing production of antibody. The optimal choice for therapy (if any) is controversial. Splenectomy is indicated in acute ITP only for life-threatening bleeding. Approximately 80% of children have a spontaneous resolution of ITP within 6 months after diagnosis. Serious bleeding, especially intracranial bleeding, occurs in fewer than 1% of patients with ITP. There is no evidence that early treatment prevents intracranial bleeding.
ITP that persists for 6 to 12 months is classified as chronic ITP. Repeated treatments with IVIG, IV anti-D, or high-dose pulse steroids are effective in delaying the need for splenectomy. Secondary causes of chronic ITP, especially SLE and HIV infection, should be ruled out. Splenectomy induces a remission in 70% to 80% of childhood chronic ITP cases. The risks of splenectomy (surgery, sepsis from encapsulated bacteria, pulmonary hypertension) must be weighed against the risk of severe bleeding.