Why do Rh-negative women tend to have a positive antibody screen compared to Rh-positive women of childbearing age?

The reason Rh-negative women tend to have a positive antibody screen compared to Rh-positive women of childbearing age is primarily because they have formed active anti-D antibodies. This formation occurs when an Rh-negative individual is exposed to Rh-positive blood, whether through pregnancy or transfusion. Since Rh-negative women can produce anti-D in response to such exposure, they may show a positive antibody screen as a reflection of this immune response to the D antigen on Rh-positive red blood cells.

In contrast, Rh-positive women do not produce anti-D antibodies because they possess the D antigen on their own red blood cells. As such, their immune system is not triggered to form these antibodies, resulting in a negative antibody screen.

While the administration of Rh immunoglobulin (RhIg) is crucial for preventing Rh alloimmunization in Rh-negative women who have been exposed to Rh-positive blood, it specifically aims to prevent the formation of anti-D. Women who have received RhIg typically should show negative antibody screens because the immunoglobulin neutralizes Rh-positive cells and prevents immune response development. Thus, they may not exhibit a positive screen like Rh-negative women with unneutralized exposure.

The other options are less relevant in this context. The formation of anti-K (anti-Kell