What is the test to measure fetomaternal hemorrhage?

The Kleihauer-Betke stain is specifically designed to detect and quantify fetal hemoglobin in maternal blood, making it the appropriate test for measuring fetomaternal hemorrhage. This test is particularly useful in cases where there is a concern for maternal-fetal blood mixing, as it can indicate the extent of fetal blood that has entered the maternal circulation.

In cases of suspected fetomaternal hemorrhage, such as after trauma or in certain pregnancy complications, knowing the quantity of fetal blood in the maternal circulation is critical for managing issues like Rh sensitization and for making clinical decisions regarding further interventions, such as the administration of Rho(D) immune globulin.

The Coombs test, while important for determining the presence of antibodies and assessing compatibility issues between maternal and fetal blood, does not specifically quantify the volume of fetomaternal hemorrhage. Blood type determination helps to identify the Rh factor but does not provide insights into the volume of fetal blood transferred to the mother. The complete blood count (CBC) with differential gives general information about the blood cells but does not directly assess fetomaternal hemorrhage. Therefore, the Kleihauer-Betke stain is the most appropriate choice for the assessment of fetomaternal hemorrhage.