Rh alloimmunization: Doppler or amniotic fluid analysis in the prediction of fetal anemia?

Objective: Compare the results of amniocentesis and those of middle cerebral artery peak systolic velocity to detect anemic fetuses in Rh alloimmunized pregnancies.

Method: Descriptive observational study involving 99 consecutive Rh-negative pregnancies: 74 alloimmunized patients submitted to amniotic fluid spectrophotometry (group 1) and 25 alloimmunized cases managed with Doppler ultrasonography (group 2). Variables analyzed were the following: need for neonatal transfusion and neonatal hematocrit.

Result: Neonatal hematocrit was significantly lower and the need for neonatal transfusion was significantly higher in cases managed with spectrophotometry compared to those managed with Doppler.

Conclusion: Infants managed with Doppler velocimetry had higher hematocrit and less need for neonatal transfusion, suggesting that this non-invasive method of monitoring fetal anemia may best preserve the neonate.