bg is an abbreviation for blood group, the full name is BLOOD GROUP and refers to the type of specific antigen on the membrane of red blood cells, which is genetically controlled, hence the name blood group antigen. Blood groups can be categorized into ABO blood groups and Rh blood groups. 1. ABO blood group system: According to whether there are A antigen and B antigen on the red blood cell membrane, blood can be divided into four types of blood, only A antigen on the red blood cell membrane is A-type blood; only B antigen on the red blood cell membrane is B-type blood; AB antigen on the red blood cell membrane is AB-type blood; AB antigen on the red blood cell membrane is not O-type blood. 2. Rh blood type system: According to whether there is D antigen on the red cell membrane, blood is divided into two types, Rh-positive blood with D antigen on the red cell membrane and Rh-negative blood without D antigen on the red cell membrane, and panda blood refers to this type of blood.