CMV screening of group-specific orders-good stewardship of the blood supply.

Background: In addition to antigen-negative red blood cells (RBC), Immunohematology Reference Laboratories (IRL) must provide RBCs that are cytomegalovirus (CMV) seronegative. Due to high percentage of CMV seropositive individuals, it is challenging to find CMV and antigen-negative RBC. The IRL selects predominantly group O donors tested for CMV, and these RBC are sometimes needed to fill orders for nongroup O patients. This study evaluated units sent that were out of group to fulfill CMV-seronegative requests.

Study Design And Methods: Requests for CMV-seronegative and antigen-negative RBCs were divided into Period 1 (January 1, 2019-February 29, 2020) before intervention and Period 2 (March 1, 2020-May 31, 2020) post intervention. ABO Rh units requested were compared to ABO Rh units provided.

Results: Period 1: 537 CMV-seronegative RBC units were provided. 99/188(52.66%) B-positive requests were fulfilled using O RBCs. 58/504 (11.51%) of D-negative units were sent to D-positive patients. Period 2: 119 CMV-seronegative RBC units were provided. 18/51 (35.29%) B positive requests were fulfilled using O RBCs. Only 7/113 (6.19%) D-negative units were sent to D-positive patients.

Discussion: For 239/656 (36.43%) CMV-seronegative antigen orders requested for B-positive patients, more than half of these orders were filled with O RBCs. To decrease group O usage for nongroup O patients, the IRL practice has changed to increase CMV testing for group B donors. Since the change in algorithm, there was a 17.37% decrease group O usage for group B patients.