RhD

The Rh factor refers to genetically determined antigens on the surface of red blood cells. The most significant of these is the RhD antigen, which is crucial in classifying blood groups.1

The Rh system was discovered in 1940 by Karl Landsteiner and A.S. Weiner, using blood from rhesus monkeys, hence the name. Individuals are classified as Rh-positive if they have the RhD antigen and Rh-negative if they lack it.1

A critical aspect of the Rh factor is its role in blood transfusions and pregnancy. If an Rh-negative person receives Rh-positive blood, their immune system can develop anti-Rh antibodies. Subsequent transfusions of Rh-positive blood can lead to a severe, potentially fatal, immune reaction where red blood cells are destroyed.1

Similarly, during pregnancy, if an Rh-negative mother carries an Rh-positive fetus, fetal red blood cells can enter the mother's bloodstream. This can cause the mother to produce anti-Rh antibodies, which may attack subsequent Rh-positive fetuses, leading to erythroblastosis fetalis, or hemolytic disease of the newborn. This condition can cause anemia, jaundice, and, in severe cases, fetal death or serious complications for the newborn. Vaccination with Rh immunoglobulin can prevent this sensitization.123