Currently, no standard of care exists in the United States to guide transfusion decisions regarding Rhesus (Rh)D type for individuals with an unknown blood type, other than for females of childbearing potential (FCPs) and neonates, according to findings from a study published in the journal Transfusion Medicine Reviews.
The researchers of the current review sought to establish the rates of anti-D alloimmunization, which can be associated with hemolytic disease of the fetus and newborn (HDFN), in RhD-negative trauma patients who receive transfused RhD-positive red blood cells (RBCs) and/or low-titer group O whole blood (LTOWB). In fact, the prevalence of anti-D alloimmunization can be linked to many different factors.
How common is alloimmunization in trauma patients?
The present study utilized the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) strategy to respond to the following Patient, Intervention, Comparison, Outcomes (PICO) question: “In trauma patients who were transfused blood, what is the prevalence of alloimmunization to the D-antigen?”
The review evaluated all early view, accepted articles published in English through April 3, 2022. They included prospective and retrospective case series/reports, randomized control studies, cohort studies, and case-control studies. Following the initial search, in an effort to ensure that the most current information was included in the analysis, relevant articles published between April 4, 2022, and Aug. 31, 2023, were added if they addressed the primary question.
Read more about HDFN testing and diagnosis
Among adult patients who experience a trauma, the incidence of anti-D alloimmunization has been shown to range between 7.8% and 42.7% among those transfused with whole blood. Among individuals transfused with RBCs, however, the incidence of anti-D alloimmunization varies from 0% to 94%, based on the number of categories that are being analyzed. With platelet transfusions, in contrast, rates of anti-D alloimmunization range from 0% to 19%. Rates of alloimmunization appeared to increase with age and were reported in children older than five years of age.
Among FCPs, the risk for adverse events, including the need for intensive and/or invasive antepartum/postpartum management of HDFN and fetal death, was reported in only 1 of 500 transfusions. Moreover, the risk for a hemolytic transfusion reaction occurred in 1 of 27,000 transfusions among all of the recipients and in one of 6600 transfusion among RhD-negative FCPs. The results of other studies, however, have reported high rates of alloimmunization of between 32.7% and 42.7% among FCPs following transfusions with RhD-positive RBC products.
Among RhD-negative pregnant females who experience a traumatic injury, the likelihood of being transfused with RhD-positive blood and carrying a fetus with HDFN varies between 2% and 6.5%, with the risk for fetal loss estimated at 0.3%.
A shortage of universal donor blood
“The critical shortage of life-saving universal donor blood is driving the dilemma over the use of RhD-positive blood in RhD-negative patients,” the study authors stated.
More than 80% of recently surveyed parents indicated that they would sanction the administration of RhD-positive blood products to their RhD-negative child if it was a matter of life or death.
Several rationales support the administration of RhD-positive RBCs to traumatically injured RhD-negative females aged ≤50 years. Rates of severe and fatal HDFN have declined since exchange transfusion was introduced in the 1940s and Rh immune globulin (RhIg) in the 1960s.
Although recent guidelines recommend administering RhIg to all traumatically injured individuals who are both pregnant and RhD-negative, no specific guidance focuses on pregnant or nonpregnant RhD-negative patients who have received RhD-positive RBC and platelet transfusions.
“[R]ather than focusing on policies, we need to still capture the occurrence,” the authors noted. “Prior to establishing these guidelines, the initial step involves establishing a system for standardized data collection,” the authors stated. “As out trajectory propels us [toward] precision medicine and tailored transfusion practices, gaining a big data approach becomes indispensable.”
