Changes in middle cerebral artery velocimetry of fetuses diagnosed postnatally with mild or moderate hemolytic disease.

OBJECTIVES To determine the longitudinal trends of middle cerebral artery peak systolic velocity (MCA PSV) in fetuses with mild or moderate hemolytic disease according to the need for postnatal therapy. DESIGN Prospective cohort study. SETTING University referral center. SAMPLE Twenty-three fetuses from singleton alloimmunized pregnancies. METHODS Serial measurements of MCA PSV were performed. After delivery, newborns were grouped by the need for postnatal management into mild hemolytic disease, which required no or only phototherapy (n = 14, group 1), and moderate hemolytic disease, where postnatal top-up or exchange transfusions were required (n = 9, group 2). MAIN OUTCOME MEASURES Serial Doppler MCA PSV data transformed to multiples of the median, analyzed with linear regression and exponential models. RESULTS We performed 83 measurements in group 1: 3-8 per fetus; mean GA at inclusion, 23 weeks and 65 measurements in group 2: 4-15 per fetus; mean GA at inclusion, 22 weeks. The estimated mean slopes of the MCA PSVs increased with the degree of postnatal therapy required (group 1: MCA PSV = 0.003 GA + 1.298; group 2: MCA PSV = 0.035 GA + 0.436). The relative average increments (RAI) were 4.7% and 7.1%, respectively. The two groups exhibited significant differences in mean slope and RAI (p<0.05). CONCLUSIONS Fetuses that required postnatal transfusions due to hemolytic disease showed an enhanced progressive increase in MCA PSVs compared to those without transfusion requirement. This information might enable their identification during pregnancy.