Which blood unit should be selected for exchange transfusion for a newborn who is group A, Rh-positive with a mother who is group A, Rh-positive and has anti-c?

For a newborn with blood group A, Rh-positive whose mother is also group A, Rh-positive and possesses anti-c antibodies, the selection of blood for exchange transfusion is critical. The ideal blood unit should match the newborn's ABO and Rh status while being negative for the corresponding antibodies that the mother possesses, particularly anti-c.

Choosing a unit that is group A and Rh-positive is appropriate since it matches the infant's blood type. The Rh-status must be positive to ensure compatibility, given the infant's Rh-positive status. Furthermore, the presence of anti-c in the mother means that the transfused blood must not have the c antigen to prevent hemolytic reactions. Therefore, using A, CDe/CDe provides the necessary compatibility where the "CDe" indicates that this unit does not express the c antigen, thereby avoiding any complications due to the mother's anti-c antibodies.

Options that contain units expressing the c antigen would present a risk for hemolysis, making them unsuitable for a newborn needing exchange transfusion in this scenario. As a result, selecting A, CDe/CDe matches the clinical requirements for ABO and Rh compatibility, as well as avoiding the risk associated with the mother's anti-c antibodies.