Rhesus Negative Pregnancy

Question 1

Why is rhesus status important?

Answer 1

15% of mother are Rh -ve
If Rh -ve mom has Rh +ve baby, fetal red blood cells may leak causing anti-D IgG antibodies to form in mother
in later pregnancies these can cross placenta and cause haemolysis in fetus or in the same pregnancy in case of recurrent leak

Question 2

How is rhesus reaction prevented?

Answer 2

1. Test for D antibodies in all Rh -ve mothers at booking
2. Give anti-D to non-sensitised Rh -ve mothers at 28 and 34 weeks

Anti-D must be given prophylactically as once sensitization has occured it is irreversible.
if event is in 2nd/3rd trimester give large dose of anti-D and perform Kleihauer test - determines proportion of fetal RBCs present

Question 3

When should anti-D immunoglobulins be given ASAP?

Answer 3

delivery of a Rh +ve infant, whether live or stillborn
any termination of pregnancy
miscarriage if gestation is > 12 weeks
ectopic pregnancy (if managed surgically, if managed medically with methotrexate anti-D is not required)
external cephalic version
antepartum haemorrhage
amniocentesis, chorionic villus sampling, fetal blood sampling
abdominal trauma

Should always be given within 72 hours

Question 4

What tests should be performed for rhesus -ve?

Answer 4

1. All babies born to Rh -ve mother should have cord blood taken at delivery for FBC, blood group & direct
2. Coombs test: direct antiglobulin, will demonstrate antibodies on RBCs of baby
3. Kleihauer test: add acid to maternal blood, fetal cells are resistant

Question 5

What are signs of an affected fetus (rhesus -ve)?

Answer 5

oedematous (hydrops fetalis, as liver devoted to RBC production albumin falls)
jaundice, anaemia, hepatosplenomegaly
heart failure
kernicterus

Question 6

What is treatment for an affected fetus (rhesus -ve)?

Answer 6

Transfusions, UV phototherapy