Hemolytic transfusion reaction occurs when grossly incompatible blood is administered to patients with preformed alloantibodies. -Acute reaction -usually because of clerical errors. C/F- High grade fever Chills Rigors Flank Pain Oozing of blood from venepuncture Massive hemolysis of the transfused blood may be associated with severe complications, including hypotension, renal failure, and even death. Disseminated intravascular coagulation and Hemolytic uremic syndrome are not characterized by a positive Coombs test. Autoimmune hemolytic anemia is not related to blood transfusions.