Provision of KEL1-negative blood to obstetric patients: a 3-year single-institution retrospective review.

BACKGROUND: KEL1 alloimmunization is a major cause of hemolytic disease of the fetus and newborn (HDFN). While select countries have guidelines for preventing transfusion-associated KEL1 alloimmunization, the United States does not. Beth Israel Deaconess Medical Center instituted a policy in April 2009 whereby women not more than 50 years of age on the obstetric service were transfused KEL1-negative red blood cells (RBCs). We sought to determine compliance and impact for prevention of KEL1 alloimmunization and HDFN.

STUDY DESIGN AND METHODS: All women not more than 50 years of age without anti-K transfused RBCs during an obstetric admission from April 9, 2009, to April 9, 2012, were identified (227). Adherence to policy, factors contributing to nonadherence, and subsequent impact were evaluated. For comparison, all cases of anti-K detection in women not more than 50 years of age admitted to nonobstetric services and all cases of transfusion-associated KEL1 alloimmunization in women not more than 50 years of age during the 10 years prior were identified.

RESULTS: Eighty-four percent received only KEL1-negative units. Three (1.3%) women not more than 50 years of age on the obstetric service were identified with anti-K, while 17 (1.5%) women not more than 50 years of age on nonobstetric services had anti-K detected; only five of 20 had a prior RBC transfusion. In the 10 years prior, there were 27 cases of transfusion-associated KEL1 alloimmunization in women not more than 50 years of age. There were no cases of KEL1 HDFN in either period.

CONCLUSION: Although the findings demonstrate feasibility of providing KEL1-negative RBCs to women of childbearing potential, evidence for clinical benefit is lacking. The low prevalence of KEL1 in blood donors, the lack of significant differences in alloimmunization rates, and no cases of HDFN during the study period questions the clinical benefit of such a policy.