Rh incompatibility
Rh Factor
Detected only on the red cell surface.
Sub groups - C, c, D, E, e
D is more antigenic.
If D antigen is present Rh +, if absent Rh –
Antibodies (agglutinins) to Rh factor is not developed spontaneously in Rh – individuals without having exposure to Rh antigen.
Sensitisation to Rh Factor
May occur
Following transfusion of Rh + blood to Rh – individuals
In events related to pregnancy (abortion, anti-partum haemorrhage, delivery) having Rh + fetus in Rh - mother
Haemolytic Disease of the Newborn
Rh incompatibility is less commoner – severe.
Other causes for haemolytic disease of newborn.
ABO blood group incompatibility.
“minor” blood group incompatibilities.
Rh Incompatibility
Occurs in Rh+ babies born to Rh- mothers.
No Rh agglutinins in non sensitised Rh negative individuals.
Antibodies developed following exposure to the Rh antigen.
Rh antibodies are Ig-G type, it crosses the placenta
If Rh antibody crosses the placenta of Rh+, haemolysis occurs in fetal blood.
Consequences of Rh Incompatibility
Haemolytic disease of the newborn
(Erythroblastosis fetalis)
Death inutero
Hydrops fatalis
Kernicterus
Usually 1st child is normal
≈17% children in 2nd pregnancy of Rh – mothers are affected
Prevention
Prevention of sensitisation in Rh – mothers to Rh factor
Avoiding transfusion of Rh+ blood to Rh – women
Treating with Rh antibodies to mothers who have exposed to Rh antigen within 48 hours of exposure (following miscarriage, still birth or delivery).
Rh immune globulin (RhIG) or Rhogam.
Passively acquired antibodies destroy any fetal cells in her circulation before they can elicit an active immune response.
Treatment for Rh Incompatibility
Mild disease - no treatment.
if jaundice is significant - need to treat.
Why
Kernicterus (Bilirubin can cross the blood brain barrier and causes damage to basal ganglia
It may leads to deafness
Treatment for Rh Incompatibility
Phototherapy
Convert bilirubin into water soluble isomers
Exchange transfusion