What situation would concern the nurse about the presence of Rh incompatibility?

Choice A rationale Rh incompatibility arises when an Rh-negative mother carries an Rh-positive fetus. Fetal red blood cells (RBCs) can enter the maternal circulation, particularly during birth or placental trauma. Since the mother lacks the Rh(D) antigen, her immune system recognizes it as foreign and produces anti-D antibodies (IgG), which can cross the placenta in subsequent pregnancies and cause fetal hemolysis. Choice B rationale If both the mother and fetus are Rh-positive, the mother already possesses the Rh(D) antigen on her red blood cells. Therefore, the fetal Rh-positive red blood cells are not recognized as foreign by the maternal immune system, and no anti-D antibodies will be produced to cause an incompatibility reaction. Choice C rationale If both the mother and fetus are Rh-negative, neither possesses the Rh(D) antigen. Consequently, there is no antigen-antibody mismatch to trigger an immune response, and the mother's immune system will not produce the antibodies necessary to cause Rh incompatibility issues. Choice D rationale If the mother is Rh-positive and the fetus is Rh-negative, the fetal red blood cells lack the Rh(D) antigen. The mother's immune system, being Rh-positive, will not be stimulated to produce anti-D antibodies, as there is no foreign antigen present to initiate an alloimmunization response.