Rh factor

This term is a technical medical designation used primarily in hematology and transfusion medicine. It refers specifically to the D antigen; while there are other Rh antigens, in clinical practice, the term is almost exclusively used to denote the positive or negative status of the D protein.

In a clinical setting, the term is used as a binary classifier. A person is described as Rh-positive if the protein is present and Rh-negative if it is absent. This distinction is critical for preventing hemolytic disease of the newborn and ensuring safe blood transfusions.