HDN Flashcards
list the most common/significant antibodies that cause HDN
anti-E anti-c anti-C anti-K anti-Fy^a
what is the prenatal testing required ?
- History of pregnancy & Transfusion
- ABO group
- Rh typing (including weak D)
- antibody screen
if the anti-body screen is negative when should we repeat the testing?
20-24 weeks later
if the antibody screen is positive what must be done?
Identify and titer antibody
what is tested for in prenatal monitoring?
- Ab titer
- Fetal Distress
How do we measure fetal distress?
-aminocentesis
or
-Cordocentesis
analyzes amniotic fluid bilirubin concentration at 450 nm
aminocentesis
determines Hg, Hot, blood type, DAT of fetus
cordocentesis
why do we preform a DAT from a Cordocentesis?
The DAT could indicate HDN because it should be Neg. Since babies don’t have antibodies formed yet and there for a positive DAT is being caused by moms antibodies binding to babies RBC’s.
when can the fetus be determined to have the gene for the D antigen?
10-12 weeks gestation
the relative concentration of all antibodies that are capable of crossing the placenta and cause HDFN is determined by______
antibody titer
what is a critical titer?
a titer that is higher than 16
T or F
The antibody titer method incudes the indirect antiglobulin phase using a reagent that is polyspecific.
F
-the reagent is mono-specific anti- IgG
T or F
The antibody titer method uses enhancement media in order to visualize the rxns?
F
- the antibody titer does not use enhancement media
How long is an antibody titer incubated for?
60 mins
If an antibody titer reaches a trigger point of 32 what then should be preformed?
-when?
Color Doppler Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV)studies
- 16 weeks gestation
Non invasive method of assessing HDFN that uses ultrasound to look at the cerebral artery of the fetus
MCA-PSV
what does the MCA-PSV measure? what does this indicate?
- the velocity of blood that is moving through the Cerebral artery of the fetus
- becomes faster with less RBC’s due to lysis
if the DAT is posiive what should be done?
elution
what characteristcs does a unit of blood need to have for a fetal transfusion?
- Fresh
- O-
- no mannitol
- CMV-
Cell that are indicative of hemolytic Rxn’s
spherocytes
what are the normal hemoglobin levels of Cordblood?
13.6-19.6g/dL
when is prenatal monitoring preformed ?
after a positive antibody screen
If an antibody titer is >16, then we will need to repeat at?
18-20 weeks gestation
what are the main distinctions between ABO HDN and RH/ other HDN?
ABO HDN: -Spontaneously aggregates
-RBC acetylcholinesterase is decreased
what is one method of detecting fetal cells in the mother?
Kleihauer-betke acid elution stain
when should Postnatal Rh immune globulin (300ug) be administered?
with in 72 hours after delivery of Rh- positive child
Rh immune Globulin that is administered:
- at 28 weeks gestation
- after abortion during first trimester
- following amniocentesis in second or 3rd trimester
antenatal Rh immune globulin
when should we do an intrauterine transfusion
- MCA-PSV indicates anemia
- Fetal hydrops is noted on ultrasound examination
- Fetal hemoglobin level is less than 10 g/dL
- amniotic fluid delta OD 450nm result is high
