Obs - Rhesus status

Question 1

which are the most important rhesus antigens?

Answer 1

D, C, c, E, and e

Question 2

what RBC isoimmunisation?

Answer 2

when there is a fetomaternal haemorrhage (where mum is rh-ve and baby rh+ve)

mum’s immune system creates antibodiies against rhesus antigens

these antibodies cross the placenta and cause fetal RBC destruction

this can lead to haemolytic disease of the newborn (more so in future pregnancies rather than in current pregnancy)

Question 3

How is rhesus screening and management carried out?

Answer 3

1. At Booking - mum Rh status checked & Maternal Anti-D antibody quantitated:

• if >15 = high risk haemolytic disease
• if less = moderate risk (recheck at 28 weeks)
  (if present check maternal antibody level every month)

OR
Do Non-invasive prenatal dagnosis in mum (cffdna) to check fetus rh status

OR

2. Partner rh status (if known):
   - Dd : do cffdna
   - DD : fetus is definetely rh +ve (D +ve)

Rh+ve baby:
Fetal US, MCA Doppler - assess anaemia
May need in utero transfusion
Consultant led care

Deliver at 37 weeks and check CORD blood for 3 things at birth:
Anaemia (Hb),
Hyperbilirubinaemia
DAT

Question 4

how do we test for fetal anaemia in utero? list some signs

Answer 4

1. Doppler US of peak velocity in systole (PSV) of fetal MCA has high sensitivity of fetal anaemia before 36 weeks
   1b. Very severe anaemia (<5) is detectable as fetal hydrops or excessive fetal fluid
2. If anaemia suspected -> US-guided fetal blood sampling
   o Needle insertion in umbilical vein at cord insertion at placenta
   o Or intrahepatic vein
   o Risk of fetal loss = 1%

Question 5

when is the decision to do an In Utero Transfusion made?

Answer 5

If anaemia suspected -> first do an US-guided fetal blood sampling
o Needle insertion in umbilical vein at cord insertion at placenta Or intrahepatic vein

If anaemia is confirmed then:
In Utero Transfusion - umbilical vein

Question 6

when someone is said to be rhesus +ve, what is meant by this?

Answer 6

D antigen positive

Question 7

haemolytic reactions may also occur with which other red cell antigens?

Answer 7

Rhesus antigens: D, E, c

Non-Rhesus antigens: Kell

Question 8

when is Anti-D prophylaxis given?

Answer 8

All Rh-ve women receive 1500IU at 28 weeks

receive after potentially sensitising events

Question 9

what is the kleihauer test and when is it performed?

Answer 9

Kleihauer test = assess number of fetal cells in maternal circulation,
done to guide how much anti-d is further required to be given

performed when fetomaternal haemorrhage is suspected and postnatally (within 2h)

Question 10

how can haemolytic disease of the newborn present?

Answer 10

If mild -> neonatal jaundice

neonatal anaemia - anaemia in the newborn (haemolytic disease of the newborn)

More severe -> in utero anaemia + cardiac failure, ascites and anaemia

Very severe anaemia (<5) is detectable as fetal hydrops or excessive fetal fluid

Question 11

what would the DAT show in a newborn with haemolytic disease of the newborn?

Answer 11

Positive DAT

Question 12

the antibodies that the mother makes towardsthe fetal antigens are of which type?

Answer 12

IgG