Rhesus isoimmunization
The Rh antigens on red cells result from the action of
two genes (RHD and RHCE)leading to two haplotypes
(combining c or C ,D or no D , e or E ).
- oF these Rh D is the most important in obistatrics.
- Haemolytic disease occur if an RhD-negative –
mother carries an RhD-positive child.
-There is a one in six chance of maternal ant-RhD
formation in the absence of prophylaxis.
-whether the mother develops such antibodies
depends on the amount of fetomaternal
haemorrhage and any feto-maternal ABO mismatch
may clear fetal cells before immunization occurs.
-RhD haemolytic disease of newborn most often
occurs in the second or subsequent pregnancies,
but occasionally significant fetal haemolysis occurs in
the first.
-All women should have their blood group
determined at pregnancy presentation and
again at 28-32 wks.
-A further estimation between 34 and 36 wks is
also recommended .
-when a potential sensitizing event occurs in an
RhD negative woman , whether she has
circulating anti-RhD should be determined and
an FMH estimation carried out.
