Which test would best evaluate blood type incompatibility between the mother and the fetus?

The Coombs test is specifically designed to evaluate blood type incompatibility, particularly in cases where there is a concern with Rh or ABO incompatibility between the mother and fetus. This test detects antibodies in a patient's serum that can attack red blood cells. In the context of pregnancy, a positive Coombs test would indicate that the mother has produced antibodies against the fetal blood type, which can occur in situations like Rh incompatibility.

This situation is critical because if the antibodies cross the placenta, they can lead to hemolytic disease of the newborn, which can cause serious complications. Thus, the Coombs test is essential for assessing the risk of blood type incompatibility and guiding appropriate management in pregnancy.

Other tests listed do not directly assess blood type incompatibility. Serum protein and albumin/globulin ratio focuses on the overall protein levels and balance rather than blood types. Hemoglobin electrophoresis is used primarily to identify different types of hemoglobin and diagnose conditions like sickle cell disease or thalassemia, which are not related to blood type incompatibility. The Dubowitz assessment evaluates the gestational age of newborns but has no relation to maternal-fetal blood type issues.