Rhimmunoglobulin

Rh immunoglobulin, commonly abbreviated RhIg and also known as anti-D immunoglobulin, is an immune globulin preparation containing antibodies against the Rh(D) antigen on red blood cells. It is manufactured from pooled human plasma or, in some products, as monoclonal anti-D antibodies. The purpose is to prevent maternal sensitization to Rh(D) antigens in Rh-negative individuals exposed to Rh-positive fetal or transfused red cells.

The primary use of RhIg is to prevent hemolytic disease of the fetus and newborn (HDFN) in Rh-negative pregnant women who may have Rh-positive fetal blood cells entering the maternal circulation. Mechanistically, the anti-D antibodies bind to any fetal Rh-positive red cells in maternal blood, promoting their clearance by the spleen before the mother's immune system forms active anti-D antibodies. It can also be given after events that may cause fetomaternal hemorrhage, such as delivery, miscarriage, abortion, trauma, or certain procedures, to prevent sensitization.

RhIg is typically administered by intramuscular injection. Dosing and timing depend on guidelines and the clinical event, with routine antepartum prophylaxis around 28 weeks of gestation and postpartum prophylaxis within 72 hours after delivery if the newborn is Rh-positive; additional doses may follow bleeding or invasive procedures. Safety profiles are generally favorable; common adverse effects include injection-site soreness and mild fever, while severe allergic reactions are rare. RhIg should not be given to individuals who are Rh-positive or to fetuses with Rh positivity without confirmation.

The introduction of RhIg has substantially reduced the incidence of HDFN due to Rh incompatibility and remains a standard component of prenatal care in many countries.