HDFN

Question 1

what immunoglobulin class can cross the placenta

Answer 1

IgG
Rh
Kell
Kidd
Duffy
Xga
P

Question 2

what are the two things that can be caused by HDFN

Answer 2

anemia
erythropoeisis “Erythroblastosis fetalis”

Question 3

what are some foreign antigen stimulus to red cell antigen?

Answer 3

previous transfusions
pregnancy
- fetomaternal hemorrhage
- occurs during delivery
- small amount of blood (<30 mL)
- chances of bleed increase trauma, invasive procedures

Question 4

factors that affect maternal antibody production

Answer 4

amount of blood
immunogenicity of antigen
previous exposure
maternal immune response
ABO compatibility

Question 5

why is an Rh HDN significant?

Answer 5

during the first pregnancy, the delivery is the first sensitizing event
when delivering the second baby there is a chance for a mild HDN as the second exposure will cause the titre to rise

Question 6

pathogenesis of severe cases of HDFN

Answer 6

profound anemia
hepatosplenomegaly
hypoproteinemia
cardiovascular failure
“Hydrops fetalis” severe edema

Question 7

sever cases of HDFN post partum

Answer 7

anemia
hyperbilirubinemia
hemolysis continues post partum

Question 8

severe HDFN blood groups inlude

Answer 8

all Rh antibodies
Kell
Duffy
Kidd

Question 9

mild HDFN blood groups include

Answer 9

ABO
Duffy - Fyb

Question 10

not associated with HDFN

Answer 10

Lewis, P, I

Question 11

most common HDFN blood groups

Answer 11

ABO Rh Kell

Question 12

rare HDFN blood groups

Answer 12

Kidd, Duffy, MNS, others

Question 13

disease at birth caused from ABO blood group

Answer 13

no anemia
no jaundice but increased bilirubin
spherocytes on smear

Question 14

what is the source of RhIG

Answer 14

human source acquired from pooled plasma containing anti-D
- using ion exchange chromatography
- solvent detergent to destroy lipid enveloped viruses and ultrafiltration steps (removing non enveloped viruses)

Question 15

T or F RhIG can be delivered IV or IM

Answer 15

True

Question 16

what is the use of RhIG

Answer 16

used for the prevention of anti-D production in pregnancy and given to Rh neg females
involve inhibiting the adaptive immune system by
- masking the epitope of D antigen
- increasing rate of removal of D pos infant cells by opsonization
- FcyRIIB receptor inhibition of B cells

Question 17

when is RhIG given to Rh neg females

Answer 17

28 weeks gestation
- will remove Rh pos fetal cells that enter the maternal circulation prior to giving birth
<72 hrs post delivery of Rh pos or Weak D pos infant
- removes fetal cells from circulation at the time of delivery
additional dose may be given throughout pregnancy

Question 18

what is the standard dose of RhIG

Answer 18

300 ug will clear 30 mL of whole blood an 15 mL of packed cells

Question 19

what is the half life of RhIG

Answer 19

23-26 days and can be detected up to 8 weeks in patients following injection
- can have allergens so consent is needed
- it is not effective if active anti-D is present
- it does not prevent antibody production

Question 20

other uses of RhIG

Answer 20

Rh incompatible transfusions
- given to Rh neg females of child bearing potential <45yrs who received Rh pos blood
Treament for idiopathic thrombocytopenic purpura

Question 21

prenatal testing follow up

Answer 21

if antibody screen pos
- perform Ab ID with panel
- perform titration
- antigen type mother and father

all verbally reported to physician

Question 22

what titre is significant for IgG antibodies

Answer 22

titre of 16 up
any titre of anti-K is significant
significant rise in titre - greater than two tubes

Question 23

what can cause a discrepancy in cord testing

Answer 23

Wharton’s jelly

Question 24

what is test is significant when testing baby

Answer 24

DAT

Question 25

what two methods are used to ID Ab or Ag

Answer 25

elution - removal of Ab for ID
dissociation - removal of Ab for antigen typing

Question 26

what is a fetal bleed screen (rosette test)

Answer 26

detects >30mL of Rh pos fetal cells that entered maternal circulation
- performed on maternal sample 1 hour after delivery
- if mother eligible for RhIg - FBS
- pos result means addition RhIg is requires
screening test

Question 27

what is the Kleihauer Betke test

Answer 27

determines how much Rh pos blood has entered maternal circulation
determine how many extra doses of RhIG is required
quantitates how many fetal cells there are

Question 28

procedure of Kleihauer betke

Answer 28

peripheral blood smear is treated with acid, fetal cells will remain intact because of high concentrations of hemoglobin F while adult cell is eluted out.

Question 29

what is the equation for vials of RhIg

Answer 29

% fetal cells x maternal blood volume (~5000 mL) / 30 mL

Question 30

procedure of rosette test

Answer 30

maternal 3% incubated with monoclonal anti-D at room temp, Ab will bind to infant Rh pos cells
after washing off unbound Ab indicator cells added R2R2.