University of Texas Health Science Center at San Antonio San Antonio, Texas, United States
Background/Case Studies: The San Antonio Whole Blood Collaborative has expanded the Low Titer O Type Rh(D)-positive Whole Blood (LTO+WB) transfusions since Feb 2019 to include females of childbearing potential (FCP; < 50 years age) in the trauma setting. RhIG prophylaxis in FCP with fetomaternal hemorrhage is well-established. However, protocols for RhD-mismatched transfusions are lacking. Here we describe our protocol for managing Rh(D)-neg (D-) FCP who receive LTO+WB, and we summarize key outcomes.
Study
Design/Methods: Per protocol, D- FCP who receive LTO+WB are evaluated by Obstetrics, and Transfusion medicine determines eligibility for alloimmunization prophylaxis (Eligibility criteria: D- FCP, < 50 years old, without current/historic Anti-D). Eligible D- FCP receive prophylaxis dependent on transfused red cell volume (RBCv). Patients who receive a RBCv < 20% of their total blood volume (TBV) are eligible to receive RhIG alone, while RBCv ≥20% of TBV are eligible for red cell exchange (RCX) to reduce the burden of transfused red cells, followed by RhIG. We performed a retrospective analysis between Feb 2019-Feb 2022, to determine the rate of LTO+WB transfusion to D- FCP, determine adherence to our protocol for managing RhD-mismatched transfusions, and to understand the overall rate of D antigen alloimmunization in D- females.
Results/Findings: Overall, amongst all recipients of LTO+WB, 28/1269 (2.2%) were D- females (age: 8-93), and 19/1269 (1.5%) were D- FCP (Table 1).
22/1269 (1.7%) recipients were females that did not survive the trauma event and had unknown D status with 11 (0.8%) of these being FCP.
Amongst D- FCP who received LTO+WB transfusions: -32% (6/19) were eligible for prophylactic treatment and 50% of eligible patients (3/6) received RhIg. -79% (15/19) of these patients survived. -13% (2/15) of surviving patients have adequate follow-up antibody screens. Passive anti-D due to RhIG was identified in both patients and subsequent antibody screens have been negative.
Amongst ALL D- females, including D- FCP, who received LTO+WB transfusions: -75% (21/28) of patients survived. -5% (1/21) of surviving patients formed anti-D alloantibodies within 20 days of transfusion (patient age>50 years). Conclusions: Our program is the first to provide LTO+WB to females of childbearing potential in massively bleeding settings. Overall, 1.5% of LTO+WB recipients were D-FCP. The survival rate in this population was approximately 79%. We identified only one D- female patient >50 yo that became alloimmunized. The two patients that received prophylaxis per protocol have not become alloimmunized. Future efforts and studies will focus on improving adherence to our prophylaxis protocol and follow-up. These data help to inform transfusion medicine programs considering LTO+WB transfusion in FCP in the trauma setting.
Importance of research: As the use of whole blood (LTO+WB) in the trauma setting increases in the United States, our hospital is the first to expand the program to include females of childbearing potential (FCP). Hence, we describe our protocol for managing Rh(D)-neg FCP who receive LTO+WB, and we summarize key outcomes from our 3-year experience, including overall survival and alloimmunization rates in Rh(D)-neg females who received LTO+WB.
