Postpartum acute hemolytic transfusion reactions associated with anti-Le^a in two pregnancies complicated by preeclampsia

Lewis blood group antibodies, which are mostly naturally occurring and considered clinically insignificant, have rarely been documented as a cause of acute hemolytic transfusion reactions (AHTRs). This report presents two cases of AHTRs caused by anti-Le^a occurring in postpartum black females (one group B, one group AB) whose pregnancies were complicated by preeclampsia. Neither anti-Le^a was detected by automated solid-phase red cell adherence technology in pre-transfusion testing. Therefore, red blood cell units, compatible by electronic crossmatch, were issued and transfused. The subsequent transfusion reactions were characterized by acute intravascular hemolysis, evidenced by both clinical and laboratory criteria. These two cases demonstrate that, even when least anticipated, hemolytic transfusion reactions may occur. As expected, neither live-born neonate was affected by hemolytic disease of the fetus and newborn. Because both transfusion reactions occurred in non–group O, postpartum black females with pregnancies complicated by preeclampsia, possible links between in vivo hemolytic anti-Le^a, non–group O pregnant black females, and preeclampsia may require additional investigation. Immunohematology2017;33:114–118.