Autoimmune hemolytic anemia.

Nowhere in the management of patients with autoimmune hemolytic anemias is the communication between clinician and laboratory personnel more important than in regard to blood transfusion. A clinical decision that blood transfusion is necessary must be tempered by the knowledge that transfusion has a greater-than-usual risk in this setting, both because the autoantibody may cause a shortened red cell life-span of transfused red cells and because the autoantibody makes detection of red cell alloantibodies in the patient's serum more difficult. Nevertheless, when transfusion is indicated because of anemia of life-threatening severity, blood must be provided even when there is an incompatible crossmatch caused by the autoantibody. Improved methods for the typing of antibody-coated red blood cells have been described, and several eminently practical serologic techniques are now available for detection of alloantibodies even when the patient's autoantibody reacts with all donor cells. These methods include the warm autoabsorption and the differential absorption tests as well as tests for autoantibody specificity. Thus, it is no longer justifiable to omit a search for allo-antibodies in the serum of patients with autoimmune hemolytic anemia prior to blood transfusion, and the use of "least incompatible" units without more detailed compatibility testing should be considered obsolete.