Hemolytic disease of the fetus and newborn Flashcards
what is HDFN?
the destruction of the red blood cells of a fetus and neonate by antibodies produced by the mother
what are the antibodies targeting in the fetus?
the antigens on the fetal RBCs that were inherited by the father.
what is erythroblastosis fetalis?
immature fetal RBCs are released into the circulation.
what develops at 18-20 weeks gestation?
hydrops fetalis
what do serological and clinical tests performed at appropriate times during the pregnancy accurately determine?
level of antibody in the maternal circulation
potential of the antibody to cause HDFN
severity of RBC destruction during gestation
clinical significance of ABO HDFN
can occur in the first pregnancy and in any but not necessarily all. most occur is A infants in white populations. in the black population, group B infants are more often affected
How does bilirubin affect the infants brain?
with moderate to severe hemolysis, the unconjugated or indirect bilirubin can reach toxic levels. if left untreated, it can cause kernicterous.
clinical significance of phototherapy treatment.
after delivery, the neonate can develop hyperbilirubinemia of unconjugated bilirubin and jaundice within 12 to 48 hours. Phototherapy at 460 to 490 nm is used to change it to isomers.
what happens to an RH positive first born infant of an RH negative mother?
it is unaffected because the mother has not yet been immunized
what happens when the mother is immunized?
all subsequent offspring who inherit the D antigen will be affected
how much of the fetal RBCs are needed to immunize the mother?
as little as 1mL
what happens when the mother is ABO incompatible with the fetus?
the incidence of detectable fetomaternal hemorrhage is decreased.
what is Rh0 immune globulin primarily used for?
treatment of ITP and Rh HDFN
what can prevent active immunization induced by RBC antigen?
the concurrent administration of the corresponding RBC antibody by the use of high titered RhIG
when should RhIG being given?
early in the pregnancy, early in the third trimester, or about 28 weeks gestation
when should a Rh-negative nonimmunized mother receive RhlG?
within 72 hours after delivery
the regular dose vial of RhIG contains sufficient anti D to protect against what?
15ml of packed RBCs or 30 mL of whole blood
when is RhIG considered of no benefit?
once a person has been actively immunized and has formed anti D
What does the Kleihauer Betke Test do?
used in determining the volume of fetal hemorrhage.
how do fetal RBCs appear?
they are pink while maternal cells will appear as ghost cells
what can fetal MCA-PSV with color doppler predict?
anemia in the fetus.
What is cord blood testing for?
confirmatory test for HDFN
how should the cord be collected?
it should be collected by venipuncture to avoid contamination with wharton’s jelly
