BACKGROUND: The Doppler measurement of middle cerebral artery peak systolic velocity (MCA-PSV) is considered the gold standard for the noninvasive detection of moderate to severe anemia. However, the accuracy of this test has not been evaluated so far, specifically beyond 34 weeks. OBJECTIVES: To assess the accuracy of MCA-PSV to detect moderate to severe fetal anemia and to identify risk factors associated with false-positive and false-negative MCA-PSV values after 34 weeks. STUDY DESIGN: We studied a retrospective cohort of 150 pregnant women with severe alloimmunization who delivered between 2010 and 2014 and correlated MCA-PSV and fetal or neonatal hemoglobin levels. RESULTS: Sensitivity to predict severe anemia was 69%, with a false-negative rate of 3.6%. When MCA Doppler assessment was normal, the identification of serosal effusions increased the detection rate of severe fetal anemia to 94%, with a false-negative rate of 0.8%. False-positive MCA-PSV measurements were more frequent in fetuses with 1 previous intrauterine transfusion (p = 0.0002), but were not associated with MCA resistance index, intrauterine growth restriction and fetal heart rate. CONCLUSIONS: Between 34 and 37 weeks, sensitivity of MCA-PSV Doppler assessment alone is 69% and increases to 94% when also considering signs of hydrops. False-positive MCA-PSV measurements are more frequent in case of former fetal transfusion.
BACKGROUND: The Doppler measurement of middle cerebral artery peak systolic velocity (MCA-PSV) is considered the gold standard for the noninvasive detection of moderate to severe anemia. However, the accuracy of this test has not been evaluated so far, specifically beyond 34 weeks. OBJECTIVES: To assess the accuracy of MCA-PSV to detect moderate to severe fetal anemia and to identify risk factors associated with false-positive and false-negative MCA-PSV values after 34 weeks. STUDY DESIGN: We studied a retrospective cohort of 150 pregnant women with severe alloimmunization who delivered between 2010 and 2014 and correlated MCA-PSV and fetal or neonatal hemoglobin levels. RESULTS: Sensitivity to predict severe anemia was 69%, with a false-negative rate of 3.6%. When MCA Doppler assessment was normal, the identification of serosal effusions increased the detection rate of severe fetal anemia to 94%, with a false-negative rate of 0.8%. False-positive MCA-PSV measurements were more frequent in fetuses with 1 previous intrauterine transfusion (p = 0.0002), but were not associated with MCA resistance index, intrauterine growth restriction and fetal heart rate. CONCLUSIONS: Between 34 and 37 weeks, sensitivity of MCA-PSV Doppler assessment alone is 69% and increases to 94% when also considering signs of hydrops. False-positive MCA-PSV measurements are more frequent in case of former fetal transfusion.