Rh-negative blood is panda blood, because in addition to the ABO blood group, there is also the Rh blood group, which was first discovered on the red blood cell membranes of Indian rhesus monkeys, and is divided into positive and negative blood groups according to whether there is still D antigen on the red blood cell membranes. The Rh blood type has a very important significance for clinical transfusion because only Rh-negative people can be transfused with Rh-negative blood, while Rh-positive blood cannot be transfused to Rh-negative patients, so Rh-negative patients often encounter transfusion difficulties during clinical transfusion.