Rh blood type

• Identified before blood transfusion • IgG • Reacts optimally at 37C • Can cross placenta • Rh (+): D or weak-D test is positive • Rh (-): Neg for both slide/tube and IAT testing • Immunogenic Determining the D status of an RBC sample is required when testing donor bloods. Blood for transfusion is considered Rh positive if either the D or the weak-D test is positive. Any donor blood sample that is typed Rh0 (D)-negative by the slide or rapid tube method must be tested further by an indirect antihuman globulin technique. If both tests are negative, the donor sample is considered Rh-negative. If the donor sample tests positive in any phase of Rh0 (D) testing, the sample is considered Rh-positive. Blood for transfusion is considered Rh-positive if either the D or weak-D test is positive; if both the D and weak D tests are negative, blood for transfusion is considered Rh-negative. Most Rh antibodies are IgG immunoglobulins and react optimally at 37C or following antiglobulin testing; exposure to less than 0.1 mL of Rh-positive RBCs can stimulate antibody production in an Rh-negative person.