Time to stop worrying about ABO incompatible cryoprecipitate transfusions in adults

This is the authors' abstract. We don't add key points for this paper.

Although technically accurate, this creates the perception that the risk of RBC incompatibility and plasma incompatibility are equal, when in fact they are not. ABO-incompatible RBCs are never transfused (unless in error), while ABO-incompatible plasma transfusions in the form of platelet, plasma, and cryoprecipitate are routinely performed. A lack of understanding of this concept can have significant impacts on patient care and blood product availability as exquisitely highlighted by the hesitancy of non–transfusion specialists to accept ABOincompatible COVID-19 convalescent plasma. The distinction in what is considered acceptable blood compatibility is clearly outlined in current regulations. AABB Standard 5.15.1 specifies that recipients receive “ABO group-compatible Red Blood Cell components, group specific Whole Blood, or low-titer group O Whole Blood (for non–group-O recipients or for recipients whose ABO group is unknown).” This means all transfusions containing RBCs are ABO compatible with the recipient; however, non–group-O recipients of whole blood will receive low-titer ABO-incompatible plasma. For potentially ABO-incompatible transfusions in the setting of platelet, plasma, and cryoprecipitate transfusions, AABB Standard 5.15.4 requires hospital transfusion services to “have a policy concerning transfusion of significant volumes of plasma containing incompatible ABO antibodies.” How hospitals address this standard and mitigate the risk of hemolysis from ABO-incompatible plasma transfusion varies widely. Current strategies include issuing only ABO identical or compatible units, limiting the volume of ABO-incompatible plasma, or using low titer units. For platelets, additional options include providing pooled whole blood–derived platelets, using platelets suspended in platelet additive solution, and volume reduction or washing units that are ABO incompatible. The major factor contributing to the need to transfuse incompatible plasma is product availability, with platelet transfusion being the primary example. The short shelf life of platelets makes maintaining an adequate inventory of ABO-compatible product impossible for most institutions. Currently, approximately 19% of platelet transfusions in the United States are plasma incompatible, with approximately 10% of group O units transfused to non– group-O recipients. Despite variability in practice, severe hemolytic transfusion reactions from ABO-incompatible platelet transfusions remain uncommon events. The annual US Food and Drug Administration (FDA) fatality reports identify only eight fatalities from ABO-incompatible platelet transfusions between fiscal years 2005 and 2018. Of these, seven involved transfusion of group O platelets with high titers of anti-A and/or anti-B to non–group-O recipients. This is consistent with a summary of 25 published case reports describing 30 patients, which showed that the vast majority of severe hemolytic transfusion reactions following platelet transfusion occurred when group O platelet units were transfused to group A or group AB patients. The higher risk for hemolysis associated with group O platelets may be due to the tendency of group O individuals to make higher-titer anti-A and anti-B compared to group A or group B individuals. For plasma, the adoption of fixed ratio massive transfusion protocols (MTPs) to support bleeding emergencies has resulted in increased transfusion of ABOincompatible plasma. The majority of patients in this setting will have an unknown blood type, so ideally AB plasma would be used to ensure that the plasma is always ABO compatible. MTPs, however, require blood products to be available for immediate release. It is not possible to maintain an inventory of prethawed AB plasma given that only approximately 4% of donors in the US donor population are group AB. To meet demand and avoid wastage of AB plasma, many institutions routinely Received: 1 December 2020 Accepted: 1 December 2020