At my health system, we automatically perform a delayed transfusion workup when a patient's antibody screen changes from NEG to POS, when a new antibody is identified in a patient with previous antibodies or when the DAT strength increases during a 14 day period following transfusion with RBCs. This protocol involves retesting the original sample to include ASC, AC, DAT. We also pull the segments from units transfused, perform antigen typing and perform crossmatches on the pre and post samples. We were wondering if other transfusion services perform this type of extensive workup. Thanks!