must then identify & determine in clinically significant IgG AB
If IgG AB present
paternal phenotype to determine homo or heterozygous
IgG AB are
D, E, c, C, K
Titer clinically significant ABs
titer >32 is significant; 2 tube increase in titer from previous titier is significant; reagent red cells must be of same phenotype form one titer to the next
Titer clinically significant ABs cont
if initial titer >32, 2nd titer at 18-20 weeks; if titer still >32, then amnio or percutaneous umbilical cord sampling done between 20-24 weeks; 16 or less then repeat monthly at 18-20 weeks
Amniocentesis & Cordocentesis (PUBS)
performed no later than 24 weeks
Amniotic fluid
measurement of bilirubin conc. obtained spechtophoto & plotted over time; if conc. increases then hemolysis is worsening
PUBS
obtained by cannulating umbilical vein using ultrasound
PUBS cont
blood tested for Hgb, Hct, DAT, checked for NRBCs, allows for direct transfusion
Intrauterine transfusion
performed mostly by cordocentesis; risk of trauma to placenta may cause increase AB titiers because of antigenic challege to mother from FHM
Plasma exchange & Intravenous immune globulin
done during 2nd & 3rd trimester; used to delay severe HDN until fetus is large enough for IUT
