What does Rh positive mean?

What does Rh positive mean?

• A. Rh factor is absent
• B. Rh factor is present
• C. Rh positive indicates the absence of antibodies against Rh
• D. Rh negative means the presence of antigen D

Answer: (B)

Rh positive means the red blood cells carry the D antigen on their surface. The Rh system is defined by the presence of this antigen; if the D antigen is present, blood is Rh positive, and if it’s absent, blood is Rh negative. The existence of anti-Rh antibodies is not what defines the status—antibodies can develop after exposure to Rh-positive blood, but the label Rh positive is about the antigen, not pre-existing antibodies. In short, the defining feature is that the Rh factor is present.

Rh positive means the red blood cells carry the D antigen on their surface. The Rh system is defined by the presence of this antigen; if the D antigen is present, blood is Rh positive, and if it’s absent, blood is Rh negative. The existence of anti-Rh antibodies is not what defines the status—antibodies can develop after exposure to Rh-positive blood, but the label Rh positive is about the antigen, not pre-existing antibodies. In short, the defining feature is that the Rh factor is present.