RhD-Positive Transfusion in Females of Childbearing Potential in Hemorrhagic Shock: Risk, Reality, and Policy

Prehospital transfusion using Rhesus D antigen (RhD)-positive low-titer group O whole blood (LTOWB) or red blood cells is increasingly common when RhD-negative blood products are not available. However, concerns remain regarding D-alloimmunization in RhD-negative females of childbearing potential (FCPs), which could lead to future hemolytic disease of the fetus and newborn (HDFN). The magnitude of these risks, and their policy implications, have been the subject of recent investigation. To summarize the biological and epidemiological impacts and post-exposure management of RhD-positive transfusion in FCPs in hemorrhagic shock.

This narrative review synthesizes the literature on the rate of D-alloimmunization, describes the results of modeling studies on the risk of HDFN following RhD-positive transfusion to FCPs, and examines epidemiologic studies estimating the HDFN risk at local, regional, and national levels. The D-alloimmunization risk mitigation strategies and current clinical guidelines are also reviewed.

Several factors, including the low prevalence of RhD-negative individuals, the low rate of D-alloimmunization itself, potentially reduced pregnancy rates post-trauma, and advances in modern perinatal care decrease the overall risk of HDFN following the transfusion of RhD-positive blood products to FCPs in trauma. Some modeling studies estimated that fetal death due to anti-D-mediated HDFN would occur in fewer than 0.1% of FCPs exposed to RhD-positive blood products. Timely prehospital transfusion has demonstrated survival benefits for injured adults and children. National and regional epidemiological studies support the safety and utility of RhD-positive blood product use in emergency settings. Risk mitigation strategies include Rh immune globulin (RhIg) administration and structured post-exposure follow-up to detect alloimmunization and reduce potential future pregnancy harm.

RhD-positive transfusion in FCPs during hemorrhagic shock when RhD-negative products are not available is supported by current evidence and ethical considerations. The risk of future HDFN is low and favorable perinatal outcomes can be achieved when the woman has access to modern prenatal health care. Risk may be further mitigated through post-exposure protocols. Prehospital transfusion policies should reflect this risk-benefit balance by enabling access to RhD-positive blood products for all trauma patients, including FCPs, if RhD-negative blood products are not available.