haemolytic disease of the newborn (HDN)

This is a disease of the newborn characterised by massive intravascular and extravascular lysis of red blood cells due to a Rhesus incompatibility.

This is what happens in HDN:
PS Please read Rhesus typing first, in order to appreciate this
a mom is Rhesus negative, pregnant with a baby from a Rhesus positive father. In most cases the baby will be Rhesus positive.
The situation i am going to describe is what happens in a normal pregnancy, no trauma, no placenta abruptio, etc
The mom's blood circulates through the baby, and never vice versa
So the D antigen in the baby never comes into contact with the mom'c immune system.
During delivery, when the placenta breaks, there is mixing of the baby's and mom's blood. D from the baby comes into contact with the mom's immune system and she, naturally, produces anti D.
If, at this stage, nothing is done, the antiD will remain in the mom, quietly waiting.....
In the next pregnancy from the same father, mom's blood is circulating through the baby. AntiD from the mom will now agglutinate the D of/in the baby, leading to HDN.
Can you imagine the consequences of this.....this tiny little baby, still in utero, having all or almost all its RBC haemolysed? so is there no hope for little Keith??????
weel if this situation was allowed to develop, doctors can do an exchange transfusion either in utero or after the baby is born. Basically quite dangerous but there have been some successes. The baby's blood is removed, a little at a time, and fresh blood from a donor is transfused into the baby. All sorts of possible transfusion reactions , but that will keep for another post. Ta Ta