Contributed by Lirong Qu, MD, PhD, Theresa Nester, MD, and Ileana Lopez-Plaza, MD
Published on line in November 2000
A 6-hour-old baby was found to have diffuse petechiae by the nurse while changing the diaper. This apparently healthy infant girl was born from a healthy 38 year-old woman (gravida 3, para 3) who had an uneventful pregnancy and a spontaneous vaginal delivery without complications. At birth, the girl on physical examination was otherwise normal and in no distress. A platelet count performed at the time of the petechial rash was 10,000/mL. The infant was transferred to a pediatric tertiary care facility where she received random-donor platelets. Two units of platelets needed to be transfused to elicit an adequate platelet count increment. Intravenous immunoglobulin (IVIG) treatment was commenced ( 400 mg/kg/day over 5 days). Additional studies revealed no other sources of bleeding. Over the course of the next 4 days, the patient received IVIG and random donor platelets to maintain a platelet count >50,000/mL and to correct several episodes of spontaneous lower urinary tract bleeding. An attempt to obtain maternal platelets at the time was unsuccessful due to a donation deferral secondary to infection. The infant's platelet count reached a plateau of 30,000/mL by day five and gradually increased without further platelet transfusion support. The neonate was discharged from the hospital in good health. Confirmatory laboratory studies were performed and the results were as follows: maternal platelets were homozygous for HPA-3a (Baka), paternal platelets were homozygous for HPA-3b (Bakb). Maternal serum was found to contain anti-HPA-3b (Bakb) and anti-HLA antibodies.
DIAGNOSIS & DISCUSSION