Hemolytic and pseudo-hemolytic transfusion reactions: an overview of the hemolytic transfusion reactions and the clinical conditions that mimic them.

When a reaction occurs during or after the transfusion of a blood product, those involved in the care of that patient tend to think first of an immunological evenł. l However, many transfusion reactions may not be immunologically mediated. The differential diagnosis of a transfusion reaction should include the many nonimmune conditions that can lead to the destruction of either donor or recipient's red blood cells. In addition, such reactions may only simulate some of the many manifestations of hemolytic transfusion reactions. Events simulating hemolytic transfusion reactions have been termed by some investigators as "pseudo-hemolytic transfusion reactions. ,,2,3 In this artiele, the postulated mechanisms of hemolytic transfusion reactions are reviewed and compared with the immediate and delayed reactions that can mimic them (TabIe l).