The differential diagnosis depends partly on the clinical circumstances associated with the hemorrhage. In a sick newborn, the differential diagnosis should include DIC, hepatic failure, and thrombocytopenia. Thrombocytopenia in an ill neonate may be secondary to consumption by trapping of platelets in a hemangioma (Kasabach-Merritt syndrome)or may be associated with perinatal, congenital, or bacterial infections; NEC; thrombotic endocarditis; PPHN; organic acidemia; maternal preeclampsia; or asphyxia. Thrombocytopenia also may be due to peripheral washout of platelets after an exchange transfusion. Treatment of a sick infant with thrombocytopenia should be directed at the underlying disorder, supplemented by infusions of platelets, blood, or both.
The etiology of DIC in a newborn includes hypoxia, hypo-tension, asphyxia, bacterial or viral sepsis, NEC, death of a twin while in utero, cavernous hemangioma, nonimmune hydrops, neonatal cold injury, neonatal neoplasm, and hepatic disease. The treatment of DIC should be focused primarily on therapy for the initiating or underlying disorder. Supportive management of consumptive coagulopathy involves platelet transfusions and factor replacement with fresh frozen plasma. Heparin and factor C concentrate should be reserved for infants with DIC who also have thrombosis.
Disorders of hemostasis in a well child are not associated with systemic disease in a newborn but reflect coagulation factor or platelet deficiency. Hemophilia initially is associated with cutaneous or mucosal bleeding and no systemic illness. If bleeding continues, hypovolemic shock may develop. Bleeding into the brain, liver, or spleen may result in organ-specific signs and shock.
In a well child, thrombocytopenia may be part of a syndrome such as Fanconi anemia syndrome (involving hypoplasia and aplasia of the thumb), radial aplasia-thrombocytopenia syndrome (thumbs present), or Wiskott-Aldrich syndrome. Various maternal drugs also may reduce the neonatal platelet count without producing other adverse effects. These drugs include sulfonamides, quinidine, quinine, and thiazide diuretics.
The most common causes of thrombocytopenia in wellnewborns are transient isoimmune thrombocytopenia andtransient neonatal thrombocytopenia. Isoimmune thrombocytopenia is caused by antiplatelet antibodies producedby the HPLA1-negative mother after her sensitization to specific paternal platelet antigen (HPA-1a and HPA-5b represent85% and 10% of cases, respectively) expressed on the fetalplatelet. The incidence is 1 in 1000 to 1 in 2000 births. Thisresponse to maternal-sensitized antibodies that produce isoimmune thrombocytopenia is analogous to the response thatproduces erythroblastosis fetalis. The maternal antiplateletantibody does not produce maternal thrombocytopenia, butafter crossing the placenta this IgG antibody binds to fetalplatelets that are trapped by the reticuloendothelial tissue,resulting in thrombocytopenia. Infants with thrombocytopenia produced in this manner are at risk for developmentof petechiae, purpura, and intracranial hemorrhage (an incidence of 10% to 15%) before or after birth. Vaginal deliverymay increase the risk of neonatal bleeding; cesarean sectionmay be indicated.