Rh/ABO

Hemolytic Disease of the Newborn

  • Aka erythroblastosis fetalis

  • From ABO or Rh incompatibility

ABO incompatibility affects first pregnancy

  • Mother has anti-A or anti-B IgG (can cross placenta)antibodies

    • Less severe: IgM antibodies (that don't cross placenta) and later development of antigen on fetal RBC

  • ↑ risk if mom has O blood

  • SSX of neonatal hemolysis

    • Hepatosplenomegaly, jaundice

Rhesus (Rh) incompatibility

  • Rh negative mom develops IgG AB from exposure to Rh antigen on Rh positive fetus

  • Second pregnancy ➔ hydrops fetalis/fetal hemolysis

    • Neonatal jaundice ➔ ↑ unconjugated bilirubin ➔ kernicterus (encephalopathy)

  • Rh typing

    • Rh-negative mothers need screening for anti-D antibodies at initial visit

      • If unsensitized (no anti-D antibodies): Repeat antibody screening at 28wks AND delivery

      • If sensitized (anti-D antibodies >1:8): Amniocentesis/imaging for hemolysis

      • Rosette test confirms if there was fetomaternal hemorrhage

  • Anti-D immunoglobulin (RhoGAM)

    • 300µg (1500 IU) IV or IM for every 30mL of fetal blood volume

    • Antibody-mediated immunosuppression for unsensitized, Rh negative mothers

      • RhoGAM doesn't help if mom already developed antibodies

      • Administer at 28wks AND 72hrs after birth of Rh positive baby

    • Also given to Rh negative women s/p ectopic, miscarriage, bleeding in pregnancy, termination, amniocentesis, chorionic villus sampling