HDFN

Question 1

What is HDFN also known as

Answer 1

Erythroblastosis fetalis

when fetal newbron red cells are destroyed by material IgG
-placenta is a barrier between maternal and fetal cells
-reduces the chances of AB production

Question 2

What is feto maternal hemorrhage

Answer 2

-when fetal cells get into maternal circulation

can occur
-after aminocentesis
-abortion
-cordocentesis
-ectopic preganancy
-abdominal trauma

Most common cause of the Fetal Maternal Hemorrhage is the separation of the placenta at birth

Question 3

What occur in the 2nd pregnancy

Answer 3

-IgG crosses the placental barrier
- AB binds to fetal AG
-Macrophages destroy RBC in fetal liver and spleen

Question 4

What is indirect bilirubin
what happens to it

how is it made

Answer 4

• made from HGB that is released from damaged red cells

-transported across the placenta and conjugated by maternal liver and excreted by mom harmlessly

Question 5

What is Erythroblastosis Fetalis

Answer 5

• as RBC destruction occurs the fetus becomes anemic
  -fetal liver and spleen enlarge as erythropoiesis increases to compensate for destruction
  -immature red cells are released into fetal circulation
  -is left untreated can cause cardiac failure or hydrops fetalis - edema in fetus

Question 6

What occurs after delivery

Answer 6

-red cells destruction continued
-NB liver doesnt have the liver enzymes to conjugate indirect bili (glucuronyl transferase)
-if small amounts of BC are released it then binds to albumin moves around no harm

Question 7

What happens when the binding capacity of the albumin is exceeded:

Answer 7

-BC binds to tissues to cause jaundice
-can bind CNS tissues
-cause brain damage - Kernicterus
-possible death

Question 8

difference in the effect of HDFN of a fetus compared to the newborn

Answer 8

-bilirubin metabolism
-before delivery mom can excrete bilirubin but after the fetus must excrete it

Question 9

Three important factors must be present for HDFN to occur

Answer 9

-mom MUST produce IgG which can cross the placental barrier
-fetus must have the AG mom is lacking
-AG needs to be well developed at birth

Question 10

HDFN classified into 3 categories

Answer 10

Rh (D)
ABO
OBG Antibodies

Question 11

How is Rh involved in HDFN

Answer 11

Anti D causes most severe HDFN
-RH neg moms are sensitized at first pregnancy with D positive baby
-babies that come after are sensitized
-if babies are moderately affected = slight jaundice , small TBIL elevation
-severely affected rapid red cell destruction, anemia in utero, and jaundice after delivery
-may need exchange transfusion to lower BC levels so Kernicterus can be prevented

Question 12

What is ABO HDFN

Answer 12

ABO AB in HDFN are more common than AntiD
-most dont need treatment since babies already have mildly increase BC and jaundice

Question 13

Possible explanations for the mild red cell destruction despite high
levels of maternal antibody:

Answer 13

-if there are A or B ag in tissues then secretions can bind or neutralize ABO AB
-ABO AG are poorly developed on fetal red cells
-low number of A/B antigen binding sites on fetal or infant red cells

Question 14

ABO HDFN occurs most frequently in group A or B babies born to
a Group O mother. Why???

Question 15

What is OBG HDFN

Answer 15

-if fetal cells have the IgG AG and its well developed at birth ay IgG AB can cause HDFN
-Anti c and Anti K are the most common after Anti D

Question 16

How to predict HDFN

Prenatal Testing is done for 2 reasons:

Answer 16

-ID D - negative moms who are Rhlg candidates
-ID moms with AB that can cause HDFN to assess risk to fetus

Question 17

How to predict HDFN

Prenatal Testing in the First Trimester

Answer 17

-ABO/RH
* Antibody screening for significant IgG antibodies
* Prenatal history important (para/gravida)

Question 18

What does AB titration do

Answer 18

-determines the concentration of maternal antibody
-This is helpful in aminocentesis
-Ultrasound
-Color Doppler Ultrasound
-Cordocentesis
-Fetal genotyping

If the antibody is in high concentration or rapidly elevating the baby’s risk increases.

Question 19

What cells are used for testing

If patient has Anti-E or Anti-C, what cells can we use to test the titre?

Answer 19

Homozygous and heterozygous antigen positive cells used for testing
-testing with IgG
-reported as reciprocal of highest dilution

• A titre rising by two dilutions or greater is a clinically significant change
• Any positive titre present is significant and requires notification to the
  physician

Question 20

When should baseline AB titre be determined

Answer 20

during first trimester
-then frozen for future studies
-do successive titrations to ensure validity
-test previously frozen samples in parallel to make sure the change in titer is not different because of technical variables
-repeat testing 4-6 week intervals

Question 21

What is done for in utero assessment of HDFN

Answer 21

-Amniocenteses
- done at 18-20 weeks gestation
-done to test amount of bilirubin pigment present
-the higher the levels the worse the destruction
-based on results you continue pregnancy, induce labor or do intrauterine transfusion

Question 22

how is the amniocentesis fluid tested

Answer 22

-Mass spec at 350-700mm
-Lili graph to graph Abs of BC to gestational age
-3 zones on graph determine severity
-upper zone = severe HDFN
-middle zone = moderate helps to establish a trend
-lower zone - mild

Question 23

What do we look for with Ultrasound

Answer 23

• color doppler ultrasonography to measure blood flow velocity
  -use middle cerebral artery Doppler ultrasound to asses fetal anemia.
  -if anemic the fetus will have increased cardiac output, low blood viscosity and increased flow viscosity

Question 24

What is cordocentesis

Answer 24

-venous blood sample from umbilical vein found with ultrasound
-test for Fetal Hgb, ABO/Rh/OBG antigen
phenotyping, and DAT.
-in severe HDFN, cordocentesis also can be used for direct intravascular
transfusion to the fetus

Question 25

What is fetal genotyping

Answer 25

-molecular typing of fetal DNA from maternal plasma in 2nd trimester -genotype for blood groups like D AG can help predict risk of the AB being present in pregnancy to cause HDFN -can be used to avoid aminocentesis or cordocentesis if fetus doesnt have AG for maternal AB

Question 26

Intrauterine transfusion when is it done why is it done

Answer 26

if needed based on Amniocentesis or Cordocentesis results and fetal age Used to -maintain fetal HgB to prevent heart failure -repeat every 2-4 weeks until mom can deliver early -blood delivered into peritoneal cavity or in umbilical vein -only red cells that lack the AG to mom AB are used for transfusion -XM IS and IAT with maternal plasma/serum and donor cells Phenotype donor cells (should be negative for antigen corresponding to the mom’s antibody)

Question 27

Early Delivery when is it done why is it done

Answer 27

if needed based on Amniocentesis or Cordocentesis results and fetal age -done when fetal lungs are developed 34-36 weeks gestation to limit exposure to maternal AB

Question 28

how is the intrauterine transfusion done

Answer 28

-risky because the fetal immune system is not well-developed Give: * Group O Rh negative blood * Fresh RBCs collected within 7 * Irradiated to prevent GVHD * Hemoglobin S-negative * Cytomegalovirus (CMV) negative

Question 29

How is post partum testing on cord sample done

Answer 29

-cord blood taken from NB -Wash several times to avoid a false positive from Wartons Jelly * ABO: forward testing only * RH: All infants born to Rh negative mothers have Weak D testing, if D1 and D2 are negative at IS phase * If Baby is Rh positive and Mother is Rh neg-at least one dose of RhIg is issued to the mother

Question 30

What can cause Positive DAT causes when doing post partum testing

Answer 30

* ABO incompatibility * Mother has an OBG attached to baby’s red cells * An eluate needs to be done to determine what AB is present. Elution techniques like freeze-thaw or heat methods. ABO/Rh phenotypes and DAT testing interpreted with caution if the NB has had a transfusion -most O Rh Neg PRBC can cause MF -Hem is needed to test A1c and Chem to test BC

Question 31

What is Phototherapy

Answer 31

UV light therapy used to treat increased bilirubin -UV light conjugates bilirubin -therapy for ABO HDFN

Question 32

How are neonatal transfusions done

Answer 32

-less severe cases or after initial treatment -Small aliquots of PRBC to increase the Hgb -Compatibility Testing: IS or IAT with maternal plasma -must give phenotype neg units if mom has AB present -ABO/Rh has to be compatible with Baby and mom

Question 33

How and when are Exchange Transfusions done

Answer 33

- in severe cases - most common reason hyperbilirubinemia -if you dont treat then increased BC can damage CNS -helps to correct anemia without expanding the blood volume -removes sensitized RBC and replaces them with AG neg to reduce BC levels preventing Kernicterus and also reduce level of maternal AB Baby’s blood group is confirmed using capillary or venous sample and NOT CORD SAMPLE!

Question 34

HDFN Prevention

Answer 34

ABO HDFN and OBG HDFN cannot be prevented RH HDFN can be prevented using RhIg/ RhoGAM

Question 35

What is Rh Immunoglobulin Passive Anti-D?????

Answer 35

Fractionated product -made from pooled plasma donated from people with high Anti D -has IgG anti D -300ug for 30 ml of Rh pos whole blood or 15 mk of RH pos PRBC -REDUCES not eliminated Anti D HDFN

Question 36

Who is it given to

Answer 36

-Rh Neg moms that havent made the Anti D -Antenatally during pregnancy -Postpartum - amount depends on FMH -the AB coats RH pos fetal RBC and removes from maternal circulation vascularly by macrophages and cytokines suppress moms immune system -this prevents Rh AG from getting exposed to moms immune system

Question 37

When it is given

Answer 37

-28 weeks to prevent early sensitization but Anti D can still be detectable in plasma since it is IgG human Anti D and reacts like Allo Anti D -given after birth ONLY if baby is RH pos -dont give if Anti D is already formed -T/S before Rhogam administration -addition doses from amniocentesis and trauma -only way to distinguish between passive Anti-D (RhIg) and Allo Anti-D is through patient history

Question 38

What is the rosette test for FMH

Answer 38

screen method to demonstrate presence of Rh Positive baby cells -D-negative maternal red cells and a small number of D-positive fetal red cells are incubated with Anti D -during incubation Anti D binds to D positive fetal red cells -wash and add D positive indicator red cell which binds to Anti D and forms a rosette around D positive fetal red cells -look for rosettes under a mic

Question 39

What is the Kleihauer-Betke Test for FMH

Answer 39

If Rosette test is positive Quantifies FMH -uses acid elution method -HgF is resistant to acid but Adult Hgb is not -make a smear from postpartum maternal sample and put in acid buffer -Adult Hgb breaks and hgb leave whereas fetal HGB retains it Hgb -wash, stain and look under mic -Adult cells look like ghosts but fetal cells look pink

Question 40

KLH and FMH when are they done

Answer 40

NOT FOR ROUTINE PREGNANCIES KLH on Rh positive mom to assess FMH after trauma to see if baby has bleeding RHLG given to any Rh neg mom with antepartum hemorrhage, amniocentesis, obstetrical trauma, ectopic pregnancy, and vaginal bleeding.