HDFN
What is hemolytic disease of the fetus and newborn?
A condition where fetal and newborn red cells are destoryed by maternal red cells alloantibodies. Maternal IgG is transported across the placenta into fetal circulation, and binds to fetal antigens. Those antibody coated red cells are destroyed by the fetal spleen.
What is ABO incompatibility that causes HDN?
Usually happens when type O mothers have A, B, or AB children. Type O's have anti-a and anti-b in their plasma, which are IgG and can travel through placenta and attack new born cells.
Symptoms: *hyperbilirubinemia, jaunidce
Treatment: Usually with phototherapy
Frequency: can occur in first pregnancy
What is the difference between IgM and IgG?
IgM: involved in the primary response, expressed early in the immune response, high avidity and is a pentamer meaning that it is too large to cross placenta, extensive disulfide binding, and contains 10 binding sites.
IgG: important in humoral immune effector function, secondary response, and is a monomer so it can cross placenta.
If RHIG gives the mom anti-d, it stops her from making her own antibodies against it. If we want her to not make anti-d, why are we giving her anti-d?
Fetal cells being present in maternal circulation is the "'evidence"
RHIG eliminates the positive fetal cells containing the d antigen before her own immune system even notices, and it signals her spleen to remove those RBC.
Small amounts of Rhig do not harm the fetus either.
What does a pos DAT indicate?
Could indicate HDN, detects whether maternal antibodies are coating newborn RBC, could explain symptoms like jaundice, hyperbilirubinemia, anemia (caused from ABO/RH, or other antibodies)
What is the most common cause of HDN?
ABO incompatibility
What is Rh incompatibility that causes HDN?
Happens when Rh negative mothers have Rh positive fetus. This stimulates the mom to produce anti-D in response to fetal cells containing D antigen entering her circulation. The IgG can cross placenta and enter fetal circulations and be destoryed resulting in HDN.
This usually does not occur in the first pregnancy because it requires prior sensitization.
This is the most severe type and can result in the need for aminocentesis, exchange transfusion, or intrauterine transfusion.
What are the tests that are usually performed in a prenatal package?
ABO/Rh
If Rh negative, perform weak D to ensure she is truly negative
Ab screen
If Ab screen is positive, perform AB ID, and AB titration if the antibody is clinically significant.
When do we administer RhIG?
28 weeks gestation : that is when mothers usually start to make anti-d, and a higher risk of fetal cells entering maternal circulation
Within 72 hours after delivery, abortion, miscarriage, trauma, etc: second dose if the baby is confirmed to be rH positive
12 weeks if bleeding, miscarriage, abortion, ectopic pregnancy, or other invasive procedure (aminocentesis, chorionic villus sampling)
If antenatal hemorrhage occurs after 20 weeks, an additional dose is given based on fetomaternal hemorrhage testing
What is the purpose of an elution?
Performed if DAT is positive, help ID the antibody specificity
What is the most severe case of HDN
Rh incompatibility
Explain how other antibodies can cause HDN aside from ABO/Rh antibodies?
Other clinically significant antibodies like Kell, Kidd, and Duffy can cause HDN because they are igG that can cross the placenta.
Specifically, Anti-Kell can be extreme and prevent the baby from making new blood because it attacks precursor cells.
What are the indications for an exchange transfusion?
Hyperbilirubinemia, kernicterus (bilirubin in brain tissue that can result in death), Rh induced HDN.
What is the goal of administering RHIG?
To prevent the Rh mother from forming their own anti d after exposure to rh positive red cells from the fetus
Protect against hemolytic disease of fetus and newborn
Creating passive anti-d
What is the procedure for a DAT
Run a DAT and a DAT control tube
Wash cells, add AHG reagent (not complement because babies do not make complement, or antibodies but remember we are looking for MATERNAL antibodies), spin read and record to observe for agglutination
Look at reaction macroscopically and microscopically
What is another classification of HDN besides Rh and ABO incompatibility?
HDN that is caused by other antibodies like Kell, Kidd, Duffy, S/s, U, and Lub
What is unconjugated bilirubin and provide its alternative names?
Unconjugated bilirubin is produced in the spleen, and then is transported through the blood by albumin
What is the difference between an exchange transfusion verses an intrauterine transfusion?
An intrauterine transfusionis performed on a fetus to prevent hydrops fetalis (death in womb), the needle is inserted into the umbilical vein and guided through ultrasound, then the baby is given O neg, irradiated packed RBC
An exchange transfusion is performed on a newborn (after birth), and needle is inserted into umbilical vein to remove antibody coated with anti-d and unconjugated bilirubin.
What is Wharton's Jelly? How do you eliminate it?
A gelatinous connective tissue found on umbilical cord, this can cause false results for the DAT and ABO/Rh typing, pseudoagglutination and false positives because the jelly is sticky and contains mucopolysaccharides which cause RBC to clump nonspecifically.
Eliminate by washing cord blood samples 6-8 times.
What is the klauihaur betke stain test? what is its principle?
The KB test is to quantitate the amount of fetal cells that are in maternal circulation. This helps classify the severity of the fetomaternal hemorrhage and helps calculate RHIG dosage.
The principle is that Hgb f is resistant to the added acid, but adult hemoglobin (Hgb a) is not, so fetal cells are stained bring pink, while maternal cells become ghost cells.
How many fetal cells are among 2000 maternal cells.
What are the risks of a baby who suffers from HDN?
Anemia, jaundice, kernicterus, enlarged liver and spleen, etc
What is conjugated bilirubin and provide alternative names?
Direct, water soluble
Conjugated blirubin is in the liver and reacts with glucuronic acid to become conjugated and is now water soluble.
What is RHIG made from
A concentration prepared from igG and anti-d
What tests are performed on cord blood specimens?
Wash them first to eliminate Wharton's jelly, ABO (forward typing only because newborns do not have antibodies), Rh, weak D if negative RH, DAT, and elution if DAT is positive
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