Krafts- Hemolytic Disease of the Newborn Flashcards
What is hemolytic disease of a newborn?
Hemolysis in a new born fetus d/t blood group incompatibility btwn mother and child
What is the mechanism for HDM?
Baby inherits blood group Ag (from dad) that are foreign to mom
Baby’s blood gets into mom’s circulation
Mom makes Ab to baby’s blood group Ag
Mom’s Ab attack baby’s RBCs
What are the consequences of HDM?
Extramedullary hematopoeisis
heart and liver failure (hydrops)
jaundice
Kernicterus
What antigen is involved w/ Rh incompatibility?
D Ag
The Ab response from mom is dependent on what?
How much antigen mom is exposed to?
How does the initial exposure to baby1 blood compare to the second exposure to baby2 blood?
Initial exposure usually evokes IgM (which can’t cross the placenta so the first baby is safe).
Second exposure evokes IgG, so the second may get HDN.
How do you diagnosis HDN?
DAT baby
IAT mom
What is a rhogam?
An anti-D Ab test administered at 28 weeks and w/in 72 hrs of delivery. Must quantify amt of fetomaternal hemorrhage to dose rhogam; juse kleihauer betke test or flow cytometry.
What is the kleihauer betke test?
Make smear of mom’s blood
expose smear to acid bath
stain smear
baby’s cell appear pink, mom’s appear ghostly
What is the flow cytometry test for fetal cells?
Use mom’s blood
apply anti-HbF antibody
run flow
baby cells if present are intensely positive
What is ABO incompatibility?
Occurs in 25% of pregnancies but is only severe in 1/200.
Most anti-A and anti-B Ab are IgM. Neonatal red cells express A adn B. Many cells besides red cells express Ag (sop up some of mom’s Ab). No effective protection against HDN.
How do you tx HDN?
Mild- phototherapy
severe- total exchange transfusion
Mom can undergo plasmapheresis
High dose intravenous Ig
