Incidence of Red Cell Antibody Formation Following Massive Transfusion Protocol: Experience of a Single Institution

Injured patients in hemorrhagic shock have a survival benefit with massive transfusion protocol (MTP). While there are many published studies on the transfusion management of massively bleeding patients, the risk of alloimmunization in patients that have received products during an MTP activation is relatively unknown. Therefore, we sought to determine the frequency of new antibody formation in MTP patients that received blood products from an uncrossmatched megapack.

We conducted a retrospective data review of patients who underwent an MTP activation for trauma resuscitation between May 2014 and July 2020. Data were collected from patients who met the following criteria: MTP was activated, the patients received at least one unit of packed red blood cells, one unit of fresh frozen plasma, one unit of platelets, and had a repeat type and screen within 6 weeks of transfusion. These inclusion criteria resulted in 28 patients over the 6-year timeframe.

Overall, the risk of alloimmunization secondary to MTP is 3.6% in our trauma patient population. The newly developed antibodies post-MTP are considered clinically significant, meaning they can cause hemolysis if exposed to donor red blood cells containing those antigens.

Blood products should be given preferentially over crystalloids to acutely bleeding patients to prevent ischemic injury during an MTP activation despite the risk of alloimmunization. In our single-institution study, the alloimmunization rate in massive transfusions where patients receive uncrossmatched red blood cells is similar to those receiving crossmatched red blood cells.