Red Cell Antibody GTG

Question 1

What % of pregnancies have red cell antibodies?

Answer 1

1.2%
1 in 80

Question 2

What % of women have clinical significant red cell antibodies?

Answer 2

0.4%
1 in 300

Question 3

Which antibody is most common to have in pregnancy?

Answer 3

Anti-D

Question 4

Which antibodies have severe risk of haemolytic disease of the foetus and newborn (HDFN)?

Answer 4

Anti-
D
c
K
c+E

Question 5

When should women be screened for antibodies?

Answer 5

Booking and 28 weeks

Question 6

Non invasive testing for fetal genotype is available for which antigens?

Answer 6

D, C, c, E, e and K antigens

This should be perform in 1st instance if relevant red cell antibody detected in mother

Question 7

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)

Answer 7

Consider CVS ir amniocentesis if fetal anaemia is a concern.

Should not perform if alloimmunisation has already occured

Question 8

When is non invasive fetal genotyping performed?

Answer 8

From 16 weeks, except K which is from 20 weeks.

Question 9

When should you refer to FMU?

Answer 9

Rising levels
Above specific threshold
USS suggestive of fetal anaemia

Question 10

Anti-D:
Which threshold is considered moderate risk and FMU referral should take place.

What threshold for severe risk HDFN

Answer 10

If >4

> 15 indicates severe risk HDFN

Question 11

Anti-c:
Which threshold is considered moderate risk and FMU referral should take place.

What threshold for severe risk HDFN

Answer 11

> 7.5

> 20

Question 12

Anti-K:
When should be referred to FMU

Answer 12

Refer if detect, even if risk HDFN low

Question 13

Anti-E, when to refer?

Answer 13

Refer if in presence with anti-c

Question 14

For antibodies other than D/c/K, when to refer

Answer 14

Previous HDFM or IUT
Rising titres
Titre >32

Question 15

If Anti-D/c/K present, how often should levels be monitored?

Answer 15

Every 4 weeks until 28 weeks then every 2 weeks until delivery

Question 16

If antibody present, what Qs to assess risk?

Answer 16

• Cause of alloimmunisation
• Past Pregnancy Hx and outcome
• If prev HDFN/IUT- neonatal anaemia, gestation of delivery, need for exchange transfusion/phototherapy

Question 17

If fetus has antigen corresponding to maternal antigen which is capable of causing fetal anaemia, how often should pregnancy be monitored by USS

Answer 17

Weekly by USS - fetal middle cerebral artery peak systolic velocity (MCA PSV)

Question 18

A MCA PSV above which range is concerning for fetal anaemia?

Answer 18

> 1.5 MoM, consider invasive testing

Question 19

What other signs on USS could indicated fetal anaemia/HDFN

Answer 19

Polyhydramnios
Skin oedema
Cardiomegaly

Question 20

What blood should be used for in-utero transfusion?

Answer 20

Group O negative to ABO identical, antigen negative to maternal red cell
Plasma removed, haemocrit 0.7-0.85

Question 21

If red cell antibody and high risk of bleeding (praevia, sickle cell), how often should have G+S

Answer 21

Weekly

Question 22

Which blood for maternal tranfusion

Answer 22

Same ABO
RhD type
K negative
CMV negative
Lucodepletion (for reducing risk CMV)

Question 23

Does anti-D need to be given women who have Anti-D antibodies

Answer 23

No, already sensitised

Question 24

When does anti-D not need to be given to women with are Rh -ve

Answer 24

If baby confirmed Rh negative or father confirmed Rh -ve

Question 25

When should delivery be offered to women red cell antibodies that can cause fetal anaemia

Answer 25

37-38 weeks

Question 26

What cord blood should be taken if significant antibodies present?

Answer 26

DAT, haemoglobin and bilirubin

Question 27

How should the neonate be managed?

Answer 27

Regular Obs, Bilirubin and Hb
Mother should breastfeed regularly to prevent dehydration (can increase level of jaundice)

Consider phototherapy or exchange transfusion