The positive or negative sign next to blood groups (O+, AB+, A+, B+) is known as the Rhesus (Rh) factor; a surface antigen of erythrocytes. The Rh blood group system consists of multiple antigens (over 50), but D, C, c, E, and e are the most common antigens identified. D antigen is mainly responsible for Rh disease due to its high immunogenicity.
- A+, B+, AB+, O+ have Rh protein
- A-, B-, AB-, O- do NOT have Rh protein
Fetomaternal Hemorrhage
- Rh-hemolytic disease occurs when the blood an Rh-positive fetus enters the maternal circulation of an Rh-negative woman.
- trauma
- ectopic pregnancy
- lack of prenatal care
- spontaneous or induced abortion
- normal delivery
- placenta previa
- invasive obstetric procedures
- c-section
Blood Transfusion
- Transfusion of an Rh-negative woman with Rh-positive blood, especially during an emergency.
After sensitization, anti-D IgG immunoglobulins are formed by the mother threatening future pregnancies to develop hemolytic disease of the newborn (HDN) due to Rh incompatibility if the fetus is Rh-positive.
IgG antibodies cross the placenta and cause hemolysis resulting in severe fetal anemia and hyperbilirubinemia, which can cause neurological damage or death
Rh immunoglobulins (RhIVIG) coat fetal RBCs having surface D antigen, making antigen-antibody complexes that move across the placenta before activation of the maternal immune system.
RhIVIG have a half-life of 3 months, so it is given once during 28 to 32 weeks antenatally and then in the postpartum period within 72 hours after the birth of the baby in a standard dose of 300 mcg.
