THE ROLE OF FETAL MIDDLE CEREBRAL ARTERY PEAK SYSTOLIC VELOCITY AND INTRAUTERINE TRANSFUSION IN MANAGEMENT OF FETAL ANEMIA IN RH- ALLOIMMUNIZED EGYPTIAN WOMEN

Abstract

To assess the predictive performance of the current reference values of peak systolic velocity of middle cerebral artery (MCA-PSV) in the detection of various degrees of fetal anemia in Rh-alloimmunized Egyptian women and to evaluate pregnancy outcome after prenatal treatment with ultrasound guided intrauterine fetal blood transfusion.
Materials and Methods: In a prospective study, 33 Rh-alloimmunized Egyptian women were evaluated by fetal MCA-PSV. MCA-PSV, intrahepatic umbilical venous maximum velocity (IHUV), liver length, and spleen perimeter were measured. Results before first fetal blood sampling or delivery were analyzed. Perinatal outcome was also recorded.
Results:Thresholds of ≥1.50 and ≥1.55 MOM's MCA-PSV were evaluated with all degrees of fetal anemia. For predicting moderate and severe anemia(Hb ≤0.65 MOM's), MCA-PSVof ≥1.50 MOM's has a 90.6% sensitivity, 55.0% specificity with positive likelihood ratio of 2.01 and negative likelihood ratio of 0.17 while IHUV maximum velocity sensitivity was 75%, specificity was 54%, +ve likelihood ratio was 1.4 and -ve likelihood ratio was 0.54.Sensitivity was obviously low for spleen perimeter and liver length (54%-32% respectively),also their specificity was (32%-33% respectively) in predicting moderate and severe anemia. By addition of IHUV velocity to MCA-PSV, has slightly increased test sensitivity to 94.44, almost same specificity 54.5% and predictive performance (+velikelihood ratio=2.08) and lowered false negative values. Total loss was 16/33 (48.5%) of which 25% (4/16) had miscarriage (fetal loss < 24 week) and 12 cases (36.3%) were early neonatal death in the first week of life. Ten fetuses were anemic by MCA-PSV follow up and required intrauterine transfusion. The total number of transfusions done during the study period was 23 times. Of the 10 pregnant women who required IUT, 4 fetuses (40 %) had died; 1 due to complicated IUT (fetal bradycardia) and 3 had miscarriage due to early severe fetal hydrops. Eighteen cases needed exchange transfusion within 7 days of birth.
Conclusion:It can be concluded that MCA-PSV has limited diagnostic accuracy for the prediction of moderate to severe fetal anemia in Rh-alloimmunized women. Although, it appears superior to other ultrasonographic parameters they need to be interpreted cautiously. Further work should be undertaken to develop test combinations and improve its diagnostic accuracy.
Keywords: Rh alloimmunization, fetal anemia, Doppler, Ultrasonography.