Prediction of fetal anemia with Doppler measurement of the middle cerebralartery peak systolic velocity in pregnancies complicated by maternal bloodgroup alloimmunization or parvovirus B19 infection

Objectives To confirm the relationship between the middle cerebral artery p eak systolic velocity (MCA PSV) and hemoglobin values in fetuses at risk fo r anemia (due to maternal blood group alloimmunization or parvovirus B19 in fection) and to investigate the clinical value of this method in the manage ment of these pregnancies regardless of previous transfusions. Subjects and methods Forty singleton pregnancies, 30 affected by alloimmuni zation and 10 by intrauterine parvovirus B19 infection, were referred to ou r tertiary center between 1998 and 2000. All cases underwent Doppler measur ement of the MCA PSV immediately before fetal blood sampling and just befor e and after intrauterine transfusion. Hemoglobin determination was always p erformed after diagnostic cordocentesis, before starting and after terminat ing fetal transfusion. Results Overall, we Performed 16S fetal blood samplings (hemoglobin values) and obtained 16S corresponding MCA PSV values, 140 in pregnancies complica ted by red-cell alloimmunization and 2S by parvovirus B19 infection. In ord er to adjust for the effect of gestational age on the measurements, the dat a were expressed in multiples of the median (MoM). We found a good correlat ion between MCA PSV MoM and Hb MoM in both groups (alloimmunization, r(2) = 0.6; y = 2.21 - 1.41x + 0.24x(2); parvovirus infection, r(2) = 0.68; y = 2 .09 - 0.58x - 0.16x(2)). The reduction of posttransfusion MCA PSV values wa s statistically significant (P < 0.0001). Using a threshold of 1.29 for MoM PSV, the sensitivity and the specificity of MCA pulsatility indices on pre transfusion values in predicting any degree of fetal anemia (Hb less than o r equal to 0.84 MoM) were 73.1% and 81.5% in the alloimmunization group and 100% and 100% in the parvovirus infection group, respectively. Conclusion We can confirm the presence of an inverse correlation between MC A PSV measurements and hemoglobin values in fetuses at risk for anemia due to maternal blood group alloimmunization and fetal parvovirus B19 infection . The MCA PSV is a reliable method for the prediction of anemia not only in fetuses before the first intrauterine transfusion, but also in those which have undergone one or more transfusions, with good sensitivity and specifi city in both groups of fetuses at risk.