Red blood cell donor units must be labeled for ABO and Rh. The donor's red cell D typing must be performed using anti-D reagent at the immediate spin phase. If the immediate spin test is negative, a test for weak D must be performed using 37o C incubation and an antihuman globulin (AHG) phase. If the immediate spin and weak D test are both negative, the donor is D negative and the unit is labeled Rh negative. If any part of the testing is positive, the donor is considered D positive and the unit is labeled Rh positive. The transfusing facility repeats immediate spin D typing on red cell products labeled as Rh(D) negative.