HDN Maternal Perspective Flashcards
(34 cards)
HDN definition
Maternal alloantibodies specific for inherited paternal RBC antigens, resulting in fetal/newborn RBC destruction
When do fetal RBCs sensitize mom?
- trauma
- delivery
- medical interventions
- aborted pregnancies
Test to run if HDN suspected
DAT
detects if Ab already attached to baby RBC
What alloantibody does Type O mom make against Type A or Type B baby? Can it cause HDN?
anti-A,B IgG
Can cause HDN
Test to run if DAT positive for HDN suspicion
Elution Ab ID
Traits of HDN Ab
- can cross placenta (IgG)
- not absorbed by normal tissues
- causes hemolysis (IgG1 and IgG3 more efficient)
- positive on fetal cells
Follow-up test if positive Ab ID
Ab titer
Describe Ab titer results if HDN is happening
Ab titer gets stronger in the presence of sensitizing baby Ag
List order of maternal testing
- ABO Type and screen
- Ab ID
- Ab titer if positive Ab ID
- FMH qualitative screen
- KLB or flow cytometry quantitative test
What information is gathered when diagnosing HDN?
- transfusion and pregnancy history
- type and screen
- confirm rh neg status for rhogam
- Ab ID if needed
- Ab titration baseline
Critical titer for anti-D
16-32 in AHG phase
Critical titer for anti-K
8
Significant change defined by a difference of what dilution?
2-fold dilutions
As long as the titer is less than ____, titers may be performed every 4-6 weeks
8
As little as _____ of fetal cells can sensitize mom
1 ml
95% cases diagnosed before 1968 were because of ____
D antigen
Serological detection of Weak D
- IS And AHG phase
- polyclonal anti-D
- verify with saline control
- if mutation inside RBC membrane, then don’t need Rhogam (Weak D) bc mom won’t make anti-D
Describe Rhogam protection
One dose protects mom against D-pos exposure of 30 ml bleeds for up to 12 weeks
Molecular Weak D testing
SNP panel for Weak D, run on MALIDI-Tof or other automated genotype analyzer
When to do molecular weak D testing
- woman childbearing age is weak D
- woman of childbearing age is Rh pos but has anti-D serologically demonstrated
Weak D tests mostly done for who?
Babies and donors
not moms
What is Rhogam?
High-titered IgG anti-D that immunizes D-neg mom against D Ag
Criteria for receiving Rhogam
- Rh-neg mom
- Mom no history of anti-D
Describe antepartum Rhogam dosing
- Initial dose at 28 wk gestation
- Dose follows invasive procedures amniocentesis or cordocentesis
- Dose can also follow pregnancy manipulations (abortion)
