Consensus in prenatal management of Hemolytic disease of the fetus and newborn.

Hemolytic Disease of the Fetus and Newborn (HDFN) is complication caused by maternal alloantibodies crossing the placenta and leading to the destruction of fetal red blood cells. While RhD is the most common antigen causing HDFN, Kell alloimmunization is the most severe. The assessment of HDFN risk begins with identifying the fetal antigen status. The HDFN Delphi consensus supports the use of cell-free fetal DNA (cffDNA) to determine fetal antigen status for RhD, Kell, and Rhc as a noninvasive alternative to amniocentesis. Ultrasound monitoring, including middle cerebral artery (MCA) Doppler assessments, should be initiated when antibody titers reach ≥16 for non-Kell antibodies. MCA Doppler can be started at 16 weeks' gestational age (GA) and should continue weekly until delivery. Antenatal management of HDFN involves both medical therapy with IVIg and intrauterine transfusions (IUT). Maternal IVIg can be initiated at 10-14 weeks GA for patients with a history of early intrauterine transfusion (IUT) or prior fetal/neonatal loss due to HDFN. IUT can be initiated at 16-18 weeks GA, with intraperitoneal IUT preferred before 20 weeks GA and intravascular IUT preferred after 20 weeks GA, and should be discontinued by 35 weeks GA. The timing of subsequent transfusions may be guided by hemoglobin drop calculation rates, MCA-PSV Doppler and ultrasound evaluations. Delivery is recommended at 37-38 weeks GA for those not requiring IUT and 2-3 weeks after the final IUT for those who did require IUT.