OC14.02: Middle Cerebral Artery Doppler in Fetuses with Red Cell Alloimmunisation Between 34 and 37 Weeks Gestation

To assess the performance of middle cerebral artery peak systolic velocity (MCA-PSV) to detect severe anemia (hemoglobin < 0.55MoM) in fetuses with red cell alloimmunisation between 34 and 37 weeks gestation. We studied a retrospective cohort of 202 patients with severe alloimmunisation delivered in a tertiary perinatal centre from January 2010 to December 2014. Antibodies specificities were: 40% anti D, 10% anti D + C, 7% anti Kell, 4% anti c, 39% others. All the patients underwent weekly ultrasound examination with measurement of MCA-PSV. Delivery was scheduled at 37 weeks. 45% of patients received at least one intrauterine transfusion (IUT). The MCA-PSV measurements were performed just before IUT or within 2 days before the delivery and the hemoglobin values were recorded. 222 MCA-PSV measurements were performed in 202 fetuses. Sensitivity of MCA Doppler was 52.1% to predict fetal anemia (hemoglobin < 0.82MoM) and a false positive rate of 4.0%. Sensitivity to predict severe fetal anemia (hemoglobin < 0.55MoM) was 70.0% with 2.6% false negative (4 fetuses with at least one previous IUT and 2 without IUT). Indirect signs of fetal anemia like hydramnios, pericarditis and/or ascites enabled us to diagnose severe anemia when MCA Doppler was normal and to decide to perform a Caesarean section. Abnormal fetal heart rate (FHR) monitoring helped us to detect one case of severe fetal anemia. Indirect signs of anemia and FHR increased sensitivity to 94.7%. Because of lower sensitivity of MCA-PSV Doppler measurement between 34 and 37 weeks, sonographers should look for indirect signs in order to increase the sensitivity to predict severe fetal anemia, especially in fetuses with previous IUTs. Multidisciplinary management with weekly ultrasound and FHR monitoring is needed to anticipate neonatal care, intensive phototherapy and postnatal transfusions.