THE EFFECT OF INTRAUTERINE TRANSFUSION ON FETAL BILIRUBIN IN RED-CELLALLOIMMUNIZATION

Objective: To evaluate the change in fetal serum bilirubin levels in r esponse to intrauterine transfusion for red cell alloimmunization. Met hods: The records of 37 patients who underwent more than one intrauter ine transfusion were reviewed. The following indices were extracted: p re- and post-transfusion fetal hematocrit, total and direct serum bili rubin, reticulocyte count, Kleihauer-Betke test results, volumes of in travascular and intraperitoneal transfusions, and the source used for transfusion. The data were compared for interval 1 (transfusion 1 to 2 ) and interval 2 (transfusion 2 to 3). The rates of change in bilirubi n, reticulocyte count, and percent fetal cells on the Kleihauer-Betke test were defined as the differences between the initial values of one transfusion and the initial values of the next transfusion divided by the number of days between transfusions. Analysis of variance, sign-r ank test, and linear regression analysis were used when appropriate. P < .05 was significant. Results: The median number of intrauterine tra nsfusions for each patient was 3 (range 2-8). Gestational ages ranged from 22 to 37 weeks. Total bilirubin remained above the 97.5 percentil e for gestational age in all but five patients. There was a significan t decrease in reticulocyte count and fetal cells on the Kleihauer-Betk e test, and an increase in hematocrit with serial intrauterine transfu sions. Bilirubin increased significantly after the first intrauterine transfusion (3.9 versus 5.0 mg/dL) and remained elevated thereafter. C onclusion: Fetal total serum bilirubin remains elevated with repeated intrauterine transfusions in fetal alloimmunization. Total bilirubin s hould not be used to evaluate fetal hematologic responses to the trans fusions. Copyright (C) 1997 by The American College of Obstetricians a nd Gynecologists.