Low risk of hemolysis after transfusion of uncrossmatched red blood cells

Transfusing uncrossmatched red blood cells (RBCs) can be a lifesaving bridge until crossmatched RBCs are available. The risk of using uncrossmatched RBCs is that of hemolysis from unexpected clinically significant antibodies. This study sought to quantify the risk of hemolysis after the transfusion of uncrossmatched RBCs. The records of recipients of uncrossmatched RBCs over approximately 9 months were retrieved from the regional transfusion service. Basic immunohematologic data were recorded on all recipients including the number of uncrossmatched RBCs transfused. For recipients who had either previously identified clinically significant antibodies or those identified on the day of transfusion, clinical and biochemical data were evaluated to determine whether hemolysis had occurred after uncrossmatched RBC transfusion. There were 218 recipients of 1065 units of uncrossmatched RBCs. Most of the RBCs were administered in the emergency room (48%) followed by the operating room (24%) and intensive care unit (23%). Seven (3.2%) recipients had clinically significant antibodies that were active on the day of the transfusion, whereas in four patients a clinically significant antibody had been previously identified but was not active on the day of the transfusion. One patient with active antibodies who received three units of uncrossmatched RBCs for a gastrointestinal bleed demonstrated a reactive eluate several days later as well as positive biochemical hemolysis markers. Thus the overall rate of detectable hemolysis after uncrossmatched RBC transfusion was 1 of 218 (0.5%). The use of uncrossmatched RBCs is a relatively safe intervention, although close monitoring of recipients with clinically significant antibodies for evidence of hemolysis is recommended. Immunohematology2012;28:39–44.