Red blood cell isoimmunisation describes the production of antibodies in response to an isoantigen present on an erythrocyte
Pathophysiology
Women that are rhesus-D positive do not need any additional treatment during pregnancy
When a woman that is rhesus-D negative becomes pregnant, we have to consider the possibility that her child will be rhesus positive
It is likely at some point in the pregnancy (i.e. childbirth) that the blood from the baby will find a way into the mother’s bloodstream
When this happens, the baby’s red blood cells display the rhesus-D antigen
The mother’s immune system will recognise this rhesus-D antigen as foreign, and produce antibodies to the rhesus-D antigen
The mother has then become sensitised to rhesus-D antigens
Usually, this sensitisation process does not cause problems during the first pregnancy
During subsequent pregnancies, the mother’s anti-rhesus-D antibodies can cross the placenta into the fetus
If that fetus is rhesus-D positive, these antibodies attach themselves to the red blood cells of the fetus and causes the immune system of the fetus to attack them, causing the destruction of the red blood cells (haemolysis)
The red blood cell destruction caused by antibodies from the mother is called haemolytic disease of the newborn
Management
If a sensitising event occurs, maternal isoimmunisation can be prevented via the administration of anti-D immunoglobulin
Examples of sensitising events include invasive obstetric testing, ectopic pregnancy, fall or abdominal trauma, intrauterine death, miscarriage, termination of pregnancy, delivery
Only required if mother is RhD-
It binds to any RhD+ cells in the maternal circulation, and no immune response is stimulated
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