Fetal And Neonatal Reticulocyte Count Response To Intrauterine Transfusion For The Treatment Of Red Blood Cell Alloimmunization

To examine the fetal and neonatal erythropoietic response to intrauterine transfusion (IUT) for the treatment of hemolytic disease of the fetus and newborn (HDFN). Data collected from 36 patients undergoing IUT for treatment of HDFN at The Ohio State University from 2005 to 2015 was reviewed retrospectively. IUTs were performed in women with red blood cell antibody titers >16 and associated ultrasounds findings (specifically evidence of hydrops fetalis or increased middle cerebral artery peak systolic velocity values). For each patient, we reviewed the time course of treatment, including the number of IUTs performed, the gestational ages at which these occurred, and the timing of delivery in relation to the last procedure. Fetal and neonatal hemoglobin levels and reticulocyte counts were analyzed. Reticulocyte counts in-utero and postpartum were summarized over time through profile plots and smoothed lowess curves. Regression models were used to quantify the decrease in reticulocyte counts over time, accounting for correlation within subjects with robust sandwich standard error estimates. Anti-Rh(D) (alone or in combination with other antibodies) was the most commonly encountered antibody (identified in 28 of the 36 patients). At the time of the first IUT, the median fetal hemoglobin was 5.8 g/dL (range 1.9-11.4) with a median reticulocyte count of 17.4% (range 1.3-121.7). Reticulocyte counts dropped significantly with each subsequent IUT with a median count of 4.0% (range <0.5-11.6) with the second IUT, 0.75% (range 0-5.3) with the third, and 0.5% (range 0-2.7) with the fourth. A significant decrease in reticulocyte count was observed over time. For each GA week, the reticulocyte count decreased by approximately 8.6% (95% CI: 5.3, 12.0). Laboratory results were available for 13 neonates, all of whom displayed a reticulocyte count <0.6%. Intrauterine transfusion has a direct and measurable effect on fetal reticulocyte production. Erythropoiesis suppression persists into the neonatal period. This effect can lead to prolonged anemia such that transfusion may be necessary weeks after delivery.