Noninvasive approach for the management of hemolytic disease of the fetus.

Hemolytic disease of the fetus and newborn (HDFN) is due to maternal alloantibodies directed against paternally inherited antigens on fetal red cells, and it is still a problem in affected pregnancies despite the routine use of anti-D immunoglobulin during pregnancy and shortly after delivery. The current noninvasive management of HDFN starts with the determination of fetal RhD genotype by use of cell-free fetal DNA in maternal plasma. When the fetus is antigen positive, the follow-up is performed by Doppler ultrasonography for the detection of moderate or severe anemia on the basis of an increase peak velocity of systolic blood in the middle cerebral artery. Finally, if anemia is suspected, an invasive approach is required in order to perform an intrauterine blood transfusion, which should only be attempted when the fetus needs transfusion. This approach reduces the iatrogenic conversion of mild-to-severe disease, which occurred as a result of the previous invasive management, and prevents unnecessary administration of human-derived blood products. These changes represent one of the genuine successes of fetal therapy.