In this interrupted case study, “Annie,” who is expecting her second child, visits “Dr. White” for a prenatal appointment. Dr. White orders a blood test to determine if the fetus is at risk of hemolytic disease of the fetus and newborn (HDFN). The case begins with a review of the ABO and Rh blood group systems. Students then apply their knowledge of red blood cell antigens and blood serum antibodies to explore maternal–fetal Rh incompatibility, including relevant diagnostic protocols and clinical manifestations. The case concludes with an examination of red blood cell recycling, connecting the clinical symptoms of HDFN to the underlying high rate of red blood cell destruction. Designed for use in an undergraduate anatomy and physiology course, the case offers students pursuing healthcare degrees a concise, integrated review of blood typing and maternal–fetal Rh incompatibility.