What test is used to determine if fetal blood is present in maternal circulation?

The Kleihauer-Betke stain is specifically designed to detect fetal cells in maternal blood. This test differentiates between fetal hemoglobin and adult (maternal) hemoglobin, allowing for the identification of fetal erythrocytes in maternal samples. It is particularly useful in situations where there may be a concern for fetal-maternal hemorrhage, such as after trauma or in cases of pregnancy complications.

The Rh typing test is focused on determining a mother's Rh factor in relation to fetal Rh status, which is critical for managing Rh incompatibility, but it does not detect fetal cells directly. The crossmatch test is utilized for blood transfusions to ensure compatibility between donor and recipient blood, while a complete blood count provides information about the overall health and cellular composition of blood but does not specifically identify fetal blood presence. Thus, the Kleihauer-Betke stain is the most appropriate test for identifying fetal blood in maternal circulation.