Human blood group systems

Blood compatibility testing is also routinely performed on pregnant women and on the cord blood from newborn babies, because incompatibility puts the baby at risk for developing hemolytic disease of the newborn.

[13][14] It is also used before hematopoietic stem cell transplantation, as it may be responsible for some cases of acute graft-versus-host disease.

[16] Therefore, in emergencies such as major hemorrhage, the urgency of transfusion can exceed the need for compatibility testing against other blood group systems (and potentially Rh as well).

[16] Also, blood compatibility testing beyond ABO and Rh is generally limited to antibody detection (not necessarily including forward typing).

Still, in Europe, females who require blood transfusions are often typed for the K and extended Rh antigens to prevent sensitization to these antigens, which could put them at risk for developing hemolytic disease of the newborn during pregnancy.