What is the meaning of the RH factor?
Rh factor an antigen found on the surface of red blood cells. Red blood cells with the antigen are said to be Rh positive (Rh+). Those without the surface antigen are said to be Rh negative (Rh-). Blood used in transfusions much match donors for Rh status as well as for ABO blood group, as Rh- patients will develop anemia if given R+ blood. Rh typing is also important during abortion, miscarriage, pregnancy, and birth, as mother and fetus may not be Rh-compatible. Rh stands for rhesus monkeys, in whose blood this antigen was first found.