Red Blood Cell Isoimmunisation

Question 1

What is red blood cell isoimmunisation in pregnancy?

Answer 1

When the mother mounts an immune response against antigens on foetal blood cells that enter her circulation. Resulting antibodies then cross placenta and cause foetal red blood cell destruction.

Question 2

How does exogenous anti-D work in pregnancy?

Answer 2

Exogenous anti-D mops up foetal RBCs in maternal circulation, prevents recognition by maternal anti-D and immune system.

Question 3

Who is given anti-D and when?

Answer 3

All rhesus -ve at 28/40

Question 4

What is considered a sensitisation event for administration of anti-D?

Answer 4

1. Termination of pregnancy
2. ERPC after miscarriage
3. Ectopic pregnancy
4. Amniocentesis/CVS
5. Intrauterine death
6. ECV
7. Delivery

Question 5

What steps are taken postnatally for rhesus status?

Answer 5

1. Check neonatal RhD, if +ve, give anti-D to mother.

2. Kleihauer test - could indicate large number of foetal RBCs in maternal circulation, large dose of anti-D needed.

Question 6

What are the potential outcomes of the rhesus status screening?

Answer 6

1. RhD +ve mother - no action needed

2. RhD -ve, father tested, if also negative then no action needed, if +ve then give anti-D.

Question 7

What is the consequence of mild rhesus disease?

Answer 7

Neonatal jaundice

Question 8

What are the consequences of severe rhesus disease?

Answer 8

1. Neonatal anaemia and haemolytic disease of the new born.

2. Can lead to cardiac failure, ascites, and hydrops.

Question 9

How is the foetus investigated for anaemia in rhesus screening?

Answer 9

Doppler USS of peak velocity in systole of frontal middle cerebral artery (increased in foetal anaemia).

Question 10

What is the treatment for severe foetal anaemia in rhesus disease?

Answer 10

Utero transfusion and delivery >36/40