The ABO group and Rh type classify a group of genetically inherited antigens found in the outer membrane of each red blood cell. The ABO group consists of four possibilities: A, B, AB, and O. The Rh type is either positive or negative.

What is ABO Rh type mean?

Blood type tests categorize your blood according to the major human blood group (ABO) system. A person’s ABO type depends upon the presence or absence of two genes — the A and B genes. … The Rh test determines whether this configuration is present (“Rh-positive”) or absent (“Rh-negative”) on an individual’s blood cells.

What does ABO Rh a negative mean?

Universal blood donors have type O, Rh negative blood. This means they have no A or B antigens or Rh factor on their red blood cells to which the recipient’s antibodies can react. Recipients of their red blood cells have little risk of a hemolytic transfusion reaction due to ABO or Rh incompatibility.