Which specimen is preferred for initial compatibility testing in exchange transfusion therapy?

For initial compatibility testing in exchange transfusion therapy, maternal serum is the preferred specimen. This choice is based on the significance of maternal antibodies in the context of potential hemolytic disease of the newborn or transfusion reactions. During prenatal care and in situations where a newborn may require an exchange transfusion, maternal serum can provide vital information regarding any antibodies that may have been transferred to the fetus.

Maternal serum contains antibodies that can react with the red blood cells of the infant, particularly in cases where there is Rh incompatibility or other blood group discrepancies. By analyzing maternal serum, healthcare providers can identify any potential risks for the infant which helps in selecting compatible donor blood that is less likely to cause an adverse reaction during the exchange transfusion.

While other specimens, such as the infant's postexchange serum or paternal serum, might have their own roles in subsequent testing or in assessing for specific antibodies, they are not as useful for the initial compatibility testing. An eluate prepared from the infant's red blood cells is specifically used for detecting maternal antibodies bound to the infant's cells but is not utilized at the initial stage of compatibility testing. Thus, maternal serum remains the most relevant choice for this crucial first step in the exchange transfusion process.