The Kleihauer-Betke test is performed to determine the degree of fetal-maternal hemorrhage (FMH) and to help calculate the dosage of Rh immune globulin to be given in some cases of Rh-negative mothers. A test to identify fetal red blood cells in the maternal circulation, an abnormal finding identified when fetomaternal hemorrhage has occurred. Fetomaternal hemorrhage (FMH) is the breakage of the placental barrier, allowing fetal hemoglobin to get mixed with maternal blood. In response to this, maternal immune system gets activated, and isoimmunization may occur if the mother is Rhesus-D protein negative and the fetus is RhD positive. The maternal antibodies bind to the fetal +ve erythrocytes, leading to hemolysis, anemia, hydrops fetalis and possible fetal death.