Red Cell Antibody GTG Flashcards
(27 cards)
What % of pregnancies have red cell antibodies?
1.2%
1 in 80
What % of women have clinical significant red cell antibodies?
0.4%
1 in 300
Which antibody is most common to have in pregnancy?
Anti-D
Which antibodies have severe risk of haemolytic disease of the foetus and newborn (HDFN)?
Anti-
D
c
K
c+E
When should women be screened for antibodies?
Booking and 28 weeks
Non invasive testing for fetal genotype is available for which antigens?
D, C, c, E, e and K antigens
This should be perform in 1st instance if relevant red cell antibody detected in mother
If antibody detected in mother and fetal anaemia is a concern, how can the fetal antigens be tested?
(Not D, C, c, E, e and K antigens)
Consider CVS ir amniocentesis if fetal anaemia is a concern.
Should not perform if alloimmunisation has already occured
When is non invasive fetal genotyping performed?
From 16 weeks, except K which is from 20 weeks.
When should you refer to FMU?
Rising levels
Above specific threshold
USS suggestive of fetal anaemia
Anti-D:
Which threshold is considered moderate risk and FMU referral should take place.
What threshold for severe risk HDFN
If >4
> 15 indicates severe risk HDFN
Anti-c:
Which threshold is considered moderate risk and FMU referral should take place.
What threshold for severe risk HDFN
> 7.5
> 20
Anti-K:
When should be referred to FMU
Refer if detect, even if risk HDFN low
Anti-E, when to refer?
Refer if in presence with anti-c
For antibodies other than D/c/K, when to refer
Previous HDFM or IUT
Rising titres
Titre >32
If Anti-D/c/K present, how often should levels be monitored?
Every 4 weeks until 28 weeks then every 2 weeks until delivery
If antibody present, what Qs to assess risk?
- Cause of alloimmunisation
- Past Pregnancy Hx and outcome
- If prev HDFN/IUT- neonatal anaemia, gestation of delivery, need for exchange transfusion/phototherapy
If fetus has antigen corresponding to maternal antigen which is capable of causing fetal anaemia, how often should pregnancy be monitored by USS
Weekly by USS - fetal middle cerebral artery peak systolic velocity (MCA PSV)
A MCA PSV above which range is concerning for fetal anaemia?
> 1.5 MoM, consider invasive testing
What other signs on USS could indicated fetal anaemia/HDFN
Polyhydramnios
Skin oedema
Cardiomegaly
What blood should be used for in-utero transfusion?
Group O negative to ABO identical, antigen negative to maternal red cell
Plasma removed, haemocrit 0.7-0.85
If red cell antibody and high risk of bleeding (praevia, sickle cell), how often should have G+S
Weekly
Which blood for maternal tranfusion
Same ABO
RhD type
K negative
CMV negative
Lucodepletion (for reducing risk CMV)
Does anti-D need to be given women who have Anti-D antibodies
No, already sensitised
When does anti-D not need to be given to women with are Rh -ve
If baby confirmed Rh negative or father confirmed Rh -ve
