Rh is a blood grouping system, and a positive RhD blood group indicates the presence of RhD antigen on red blood cells. The Rh and ABO blood group systems are commonly used in clinical practice, and RhD negative or positive indicates the presence or absence of Rh antigens on red blood cells; if RhD antigens are present, the blood group is RhD positive, and if RhD antigens are present, the blood group is RhD negative. Only about 5% of the Asian population is RhD-negative, while 90-95% are RhD-positive, and RhD-negative is commonly referred to as “panda blood”. When transfusing blood, special attention needs to be paid to the issue of Rh blood group compatibility. There is no natural antibody in the Rh blood group system, so there will not be any Rh blood group incompatibility when transfusing blood for the first time. However, Rh-negative recipients who receive Rh-positive blood can produce anti-Rh antibodies, and hemolytic transfusion reactions may occur when RhD-positive blood is transfused again. Therefore, blood transfusion in clinical practice usually requires the same Rh and ABO blood types to be transfused. Special attention should also be paid to the RhD blood group of pregnant women. RhD-negative mothers who give birth to RhD-positive fetuses usually do not experience hemolysis in the first pregnancy, but if the fetus is still RhD-positive in a second pregnancy, RhD antigens on the fetus’ red blood cells will cause the mother to produce anti-RhD antibodies due to the entry of the antigens into the mother’s bloodstream. The anti-RhD antibodies pass through the placenta into the fetal circulation and cause the fetal red blood cells to agglutinate, which may lead to fetal hemolysis and, in severe cases, even death.