Download Rh Factor PPT

1940 - discovered by Karl Landsteiner & Alexander Wiener
Most genetically complex of all blood type systems
Involves 45 different antigens on surface of RBCs
Controlled by genes on Chromosome 1
Rh System named after rhesus monkeys used in research
to make the antiserum for typing blood samples.
If the antiserum agglutinates your blood, you are Rh +,
if not, you are Rh-.
Inheritance can be predicted by two alleles: D & d.
D is the dominant trait while d is the recessive trait.
Here is how it may shake out genetically speaking:
DD =homozygous dominant
Rh+
Dd =heterozygous dominant
Rh+
dd = homozygous recessive
Rh-
1 out of 1000 are born with this condition.
This occurs when the mother is Rh- (dd) and the
father is Rh+ (DD or Dd). Maternal antibodies cross
the placenta and destroy fetal red blood cells. The
risk increases with each pregnancy. Often the first
born will not suffer ill effects because the mother
has not developed sufficient antibodies yet. By the
next birth, she has and complications begin to arise.
A transfer of antibodies from the mother’s system takes
place across placental boundary into the fetus.
Anti Rh+ antibodies react with fetal blood.
The RBCs of the fetus burst or agglutinate
Newborn babies may have life-threatening anemia due
to lack of oxygen in the blood.
Baby is also jaundiced, fevered, & swollen with enlarged
liver and spleen.
Massive transfusion of
Rh+ blood into the baby.
A serum (Rho-GAM) can
be given the mother at
week 28 of pregnancy
that will prevent her blood
from developing
antibodies against her
baby’s blood. It must also
be administered 72 hours
after birth, as well.