Do patients with autoantibodies or clinically insignificant alloantibodies require an indirect antiglobulin test crossmatch?

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Compatibility testing is the standard protocol that identifies suitable blood for patients requiring transfusion. If the antibody screen is negative or no clinically significant antibodies are detected, BCSH guidelines and AABB standards allow an immediate-spin crossmatch (IS XM) or even electronic issue. The testing requirement is less clear where autoantibodies or non–clinically significant alloantibodies compromise the indirect antiglobulin test crossmatch (IAT XM). Performing an IAT XM will give a mismatched result anyway, delays the supply of blood to the patient, and provides no additional benefit or safety.


From January 2002 to April 2006, the provision of blood for autoimmune hemolytic anemia (AIHA) patients with autoantibodies and no alloantibodies as well as patients with alloantibodies that exhibited a “high-titer, low-avidity” (HTLA) mode of reactivity was reviewed.


A total of 222 AIHA patients (428 samples) with autoantibodies had 1585 units of red cells supplied after IAT XM; 1308 (82.5%) were mismatched. In 50 patients (80 samples) with HTLA-like antibodies, 286 units of 328 (87.2%) were mismatched by IAT XM.


No adverse reactions were reported for the study groups where “suitable” blood was provided after a serologically mismatched IAT XM. No additional benefit for these patients can be claimed by performing an IAT XM over an IS XM, as a check of ABO match. The IAT XM is both costly and time-consuming. It is proposed that for these study group patients, a reduction to an IS XM can be applied and can be beneficial.

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