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HDN
Diagnosis
| Question | Answer |
|---|---|
| Type & screen performed when | during 1st trimester, include weak D test |
| Repeat screening when | 20-24 weeks |
| If AB screen is positive | 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 |
| Early delivery | not as necessary now with IUT |