Rhesus Disease (Haemolytic Disease of the Fetus and Newborn)
Rhesus disease is haemolytic disease of the fetus and newborn caused by maternal IgG alloantibodies crossing the placenta and destroying fetal red cells carrying the corresponding antigen; anti-D disease is largely preventable, whereas established sensitisation requires specialist fetal and neonatal surveillance.
Definition
Haemolytic disease of the fetus and newborn is fetal or neonatal red-cell destruction caused by maternal alloantibodies against fetal red-cell antigens. Rhesus disease usually refers to clinically important anti-D HDFN, but anti-c, anti-K, anti-E, anti-Duffy and other antibodies can also cause disease.
First principles
Sensitisation is the preventable step
A D-negative pregnant person can become alloimmunised when D-positive fetal red cells enter the maternal circulation, for example at birth, after bleeding, trauma, invasive procedures or another potentially sensitising event. Previous pregnancy or transfusion may already have caused sensitisation, so a first pregnancy is not automatically protected. Anti-D immunoglobulin prevents immune anti-D formation in eligible non-sensitised D-negative people; it cannot remove established immune anti-D.
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