A Rh-negative woman is pregnant with her second child. What test can be used to determine if this second child is at risk for hemolytic disease of the newborn?

The indirect antiglobulin test on the mother's serum is the appropriate test to assess the risk of hemolytic disease of the newborn (HDN) for the second child of a Rh-negative woman. This test detects the presence of Rh antibodies in the mother's blood.

In cases where a Rh-negative woman is pregnant, especially after having had a previous Rh-positive child, there is a risk that she might produce antibodies against Rh-positive red blood cells if fetal Rh-positive blood cells enter her circulation. These antibodies can cross the placenta and potentially attack the fetal red blood cells in subsequent pregnancies, leading to hemolytic disease.

By performing the indirect antiglobulin test, healthcare providers can determine whether the mother has developed these antibodies. If the test is positive, it indicates that there is a risk of hemolytic disease in the fetus, and further monitoring or interventions may be required.

In contrast, the direct Coombs test is used to detect antibodies that are already bound to red blood cells and is typically used in the diagnosis of existing hemolytic anemia rather than assessing the risk in a newborn. Hemoglobin electrophoresis identifies different types of hemoglobin and is more focused on diagnosing hemoglobinopathies like sickle cell disease or thalassem