Anti-Rh alloimmunization after trauma resuscitation

RhD-positive red blood cell allocation practice to RhD-negative patients before and during the COVID-19 pandemic

OBJECTIVES

The red blood cell (RBC) D antigen is highly immunogenic, and anti-D alloimmunization can cause hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. This study examined how RhD-negative patients who required packed RBCs (pRBCs) were handled during the COVID-19 pandemic and whether policies and practices on RhD-positive pRBC allocation to RhD-negative patients changed.

METHODS

The Association for the Advancement of Blood & Biotherapies (AABB) Clinical Hemotherapy Subsection distributed a 17-question survey to physician AABB members to elucidate the impact of the COVID-19 pandemic on the policies and practices governing the provision of RhD-positive pRBCs to RhD-negative patients.

RESULTS

There were 215 respondents who started the survey, but only 104 answered all the questions. Most institutional policies (130/155 [83.87%]) and personal practices (100/126 [79.37%]) on pRBC selection did not change during the COVID-19 pandemic. The practice of switching back to RhD-negative pRBCs after administration of RhD-positive pRBCs is variable. More than half of respondents (56/104 [53.85%]) reported offering Rh immunoglobulin to any Rh-negative patients who received RhD-positive pRBCs.

CONCLUSIONS

Despite RhD-negative pRBC supply challenges, most institutional policies and personal practices on when to provide RhD-positive pRBCs to RhD-negative patients did not change during the pandemic.

Optimizing O red blood cell concentrate usage in the emergency department in the era of patient blood management

BACKGROUND

Emergency transfusion may require the availability of O-negative red blood cell concentrates without pre-transfusion testing. At the Cliniques Universitaires Saint-Luc, the emergency department was used to having access to two decentralized O-negative red blood cell concentrates. This study aims to analyze the consumption of O-negative red blood cell concentrates in emergency situations both before and after the implementation of a novel strategy aiming at optimizing stocks. This strategy provides a combined allocation of one unit of O-positive red blood cell concentrate and one unit of O-negative red blood cell concentrate decentralized in the emergency department and reserve the transfusion of the negative unit only to under 45-year-old women and under 20-year-old men.

MATERIALS AND METHODS

A retrospective study was conducted of the transfusion and medical records of all patients who received immediate transfusions in the emergency department without pre-transfusion testing between 2008 and 2022.

RESULTS

A total of 193 patients received O red blood cell concentrates without pre-transfusion testing in emergency situations between 2008 and 2022. During the first 24 h of hospitalization, 354 O-negative units were transfused. Mean ratios of number of O-negative bags between 2008 and 2020 was 1.98 unit/patient. After implementation of the new strategy, the ratio in 2021 was 1.46 unit/patient and drastically decreased in 2022 to 0.79 unit/patient.

CONCLUSION

In situations of emergency, allocating O-negative units only for women younger than 45 years and men younger than 20 years could have saved 85% of O-negative red blood cell concentrates transfused (303/354) yet balancing the immunological risk. Limiting the number of delocalized units of O-negative red blood cell concentrates in the emergency department seems to lower O-negative consumption. With this strategy, the units spared could have been transfused to patients with greater needs (e.g., sickle cell patients or chronically transfused patients).

Management of Red Cell Alloimmunization in Pregnancy

Rhesus immune globulin has resulted in a marked decrease in the prevalence of RhD alloimmunization in pregnancy; however, antibody formation to other red cell antigens continues to occur. Evaluation for the presence of anti-red cell antibodies should be routinely undertaken at the first prenatal visit. If anti-red cell antibodies are detected, consideration of a consultation or referral to a maternal-fetal medicine specialist with experience in the monitoring and treatment of these patients is warranted. Cell-free DNA can be used to determine fetal red cell antigen status to determine whether the pregnancy is at risk of complications from the red cell antibodies. First-time sensitized pregnancies are followed up with serial maternal titers, and, when indicated, serial Doppler assessment of the peak systolic velocity in the middle cerebral artery should be initiated by 16 weeks of gestation. When there is a history of an affected fetus or neonate, maternal titers are less predictive of fetal risk; if the fetus is antigen positive, serial peak systolic velocity in the middle cerebral artery measurements should be initiated by 15 weeks of gestation because intraperitoneal intrauterine blood transfusions can be used at this gestation if needed. The mainstay of fetal therapy involves intrauterine transfusion through ultrasound-directed puncture of the umbilical cord with the direct intravascular injection of red cells. A perinatal survival rate exceeding 95% can be expected at experienced centers. Neonatal phototherapy and "top-up" transfusions attributable to suppressed reticulocytosis often are still required for therapy after delivery.

RhD-Alloimmunization in Adult and Pediatric Trauma Patients

The actual risk of providing RhD-positive units to RhD-negative recipients remains debatable. There is no standard of care in the United States (US) to guide transfusion decisions regarding RhD type for patients with an unknown blood type, except for women of childbearing age and neonates. The risk of alloantibody formation by an RhD-negative patient exposed to RhD-positive blood is reported to be from 3% to 70%. Due to such wide variations, this review was undertaken to determine the prevalence of anti-D alloimmunization in trauma patients who are RhD-negative and were transfused RhD-positive blood products. This study used the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) approach to answer the question, "In trauma patients who were transfused blood, what is the prevalence of alloimmunization to the D-antigen?" The review included all published articles through April 3, 2022 in databases. Articles published after the search period found by the authors were added to the manuscript if they addressed the primary question and there was unanimous consensus. There were 1683 full-text articles that met the search criteria, with 19 studies meeting eligibility criteria. In addition, 57 references were added after the search period had closed. The incidence of anti-D alloimmunization in adult trauma patients receiving whole blood varied from 7.8% to 42.7%. In contrast, incidence varied in patients receiving red blood cells (RBCs), from 0 to 94%, depending on number of categories analyzed. Anti-D alloimmunization with platelet transfusions varied from 0% to 19%. The alloimmunization rate increased with age and was detected only in children older than 5 years. Recent guidelines recommend the administration of Rh immune globulin (RhIG) to all traumatically injured patients who are both RhD-negative and pregnant. However, there is no specific guidance focused on the RhD-negative patient, pregnant or nonpregnant, and who have received RhD-positive red blood cells (RBC) and platelets. While numerous studies have attempted to evaluate the frequency of RhD alloimmunization rate in trauma settings, emerging data suggests that many factors affect this phenomenon. Additionally, the role of RhIG administration in cases of RhD-incompatible transfusions within the trauma setting adds complexity. As our trajectory propels us towards precision medicine and tailored transfusion practices, gaining a big data approach becomes indispensable.

Rh immune globulin immunoprophylaxis after RhD-positive red cell exposure in RhD-negative patients via transfusion: A survey of practices

BACKGROUND

Current Association for the Advancement of Blood & Biotherapies (AABB) standards require transfusion services to have a policy on Rh immune globulin (RhIG) immunoprophylaxis for when RhD-negative patients are exposed to RhD-positive red cells. This is a survey of AABB-accredited transfusion services in the United States (US) regarding institutional policies and practices on RhIG immunoprophylaxis after RhD-negative patients receive RhD-positive (i.e., RhD-incompatible) packed red blood cell (pRBC) and platelet transfusions.

RESULTS

Approximately half of the respondents (50.4%, 116/230) have policies on RhIG administration after RhD-incompatible pRBC and platelet transfusions, while others had policies for only pRBC (13.5%, 31/230) or only platelet (17.8%, 41/230) transfusions, but not both. In contrast, 18.3% (42/230) report that their institution has no written policies on RhIG immunoprophylaxis after RhD-incompatible transfusions. Most institutions (70.2%, 99/141) do not have policies addressing safety parameters to mitigate the risk of hemolysis associated with the high dose of RhIG required to prevent RhD alloimmunization after RhD-incompatible pRBC transfusions.

DISCUSSION

With approximately half of US AABB-accredited institutions report having policies on RhIG immunoprophylaxis after both RhD-incompatible pRBC and platelet transfusions, some institutions may not be in compliance with AABB standards. Further, most with policies on RhIG immunoprophylaxis after RhD-incompatible pRBC transfusion do not have written safeguards to mitigate the risk of hemolysis associated with the high dose of RhIG required.

CONCLUSION

This survey underscores the diverse and inadequate institutional policies on RhIG immunoprophylaxis after RhD exposure in Rh-negative patients via transfusion. This observation identifies an opportunity to improve transfusion safety.

Low titer group O whole blood and risk of RhD alloimmunization: Rationale for use in Finland

BACKGROUND

Prehospital low-titer group O whole blood (LTOWB) used for patients with life-threatening hemorrhage is often RhD positive. The most important complication following RhD alloimmunization is hemolytic disease of the fetus and newborn (HDFN). Preceding clinical use of RhD positive LTOWB, we estimated the risk of HDFN due to LTOWB prehospital transfusion in the Finnish population.

STUDY DESIGN AND METHODS

We collected data on prehospital transfusions in Tampere and Helsinki University Hospital areas. Using the mean of reported alloimmunization rates in trauma studies (24%) and a higher reported rate representing trauma patients of 13-50 years old (42.7%), we estimated the risk of HDFN and extrapolated it to the whole of Finland.

RESULTS

We estimated that in Finland, with the current prehospital transfusion rate we would see 1-3 cases of severe HDFN due to prehospital LTOWB transfusions every 10 years, and fetal death due to HDFN caused by LTOWB transfusion less than once in 100 years.

DISCUSSION

The estimated risk of serious HDFN due to prehospital LTOWB transfusion in the Finnish population is similar to previous estimates. As Finland routinely screens expectant mothers for red blood cell antibodies and as the contemporary treatment of HDFN is very effective, we support the prehospital use of RhD positive LTOWB in all patient groups.

Incidence of formation of anti-D between patients with and without a history of solid organ transplant

BACKGROUND AND OBJECTIVES

Solid organ transplant surgeries including liver transplants constitute a substantial risk of bleeding complications and given frequent national blood shortages, supporting D-negative transplant recipients with D-negative red blood cell products perioperatively can be difficult for the transfusion services. This study was designed to compare the incidence of alloimmunization after D-mismatched red cell transfusions between patients with and without a history of solid organ transplant at a single tertiary care hospital. The patients undergoing solid organ transplants are on strong immunosuppressive regimens perioperatively to help reduce the risk of rejection. We hypothesized that the use of these immunosuppressive agents makes these patients very less likely to mount an immune response and form anti-D antibodies when exposed to the D-positive red blood cell products perioperatively.

STUDY DESIGN AND METHODS

At our center, D-negative patients who received ≥1 unit of D-positive red blood cell products were identified using historical transfusion records. Antibody testing results were examined to determine the incidence of the formation of anti-D and any other red cell alloantibodies after transfusion and these results were compared between patients with and without a history of solid organ transplant.

RESULTS

We were able to identify a total of 22 patients over 10 years with D-negative phenotype who had undergone a solid organ transplant and had received D-positive red blood cell products during the transplant surgeries. We also identified a second group of 54 patients with D-negative phenotype who had received D-positive red blood cell products for other indications including medical and surgical. A comparison of the data showed no new anti-D formation among patients with a history of D mismatched transfusion during solid organ transplant surgeries.

CONCLUSION

Among our limited study population, we observed a very low likelihood of D alloimmunization among solid organ transplant recipients. A larger, prospective study could help further evaluate the need for prophylactic D matching for red cell transfusions during solid organ transplant surgeries.

Current advances in 2022: A critical review of selected topics by the Association for the Advancement of Blood and Biotherapies (AABB) Clinical Transfusion Medicine Committee

BACKGROUND

The Association for the Advancement of Blood and Biotherapies Clinical Transfusion Medicine Committee (CTMC) composes a summary of new and important advances in transfusion medicine (TM) on an annual basis. Since 2018, this has been assembled into a manuscript and published in Transfusion.

STUDY DESIGN AND METHODS

CTMC members selected original manuscripts relevant to TM that were published electronically and/or in print during calendar year 2022. Papers were selected based on perceived importance and/or originality. References for selected papers were made available to CTMC members to provide feedback. Members were also encouraged to identify papers that may have been omitted initially. They then worked in groups of two to three to write a summary for each new publication within their broader topic. Each topic summary was then reviewed and edited by two separate committee members. The final manuscript was assembled by the first and senior authors. While this review is extensive, it is not a systematic review and some publications considered important by readers may have been excluded.

RESULTS

For calendar year 2022, summaries of key publications were assembled for the following broader topics within TM: blood component therapy; infectious diseases, blood donor testing, and collections; patient blood management; immunohematology and genomics; hemostasis; hemoglobinopathies; apheresis and cell therapy; pediatrics; and health care disparities, diversity, equity, and inclusion.

DISCUSSION

This Committee Report reviews and summarizes important publications and advances in TM published during calendar year 2022, and maybe a useful educational tool.

The effect of motivational strategy on voluntary plasma donation, a field trial

BACKGROUND

Plasma protein therapies (PPTs) are a group of medicines extracted from human plasma through fractionation. The manufacture of adequate amounts of PPTs requires a large volume of human plasma. WHO emphasized that whole blood and blood component donations should be voluntary and non-remunerated. So, motivating people to donate plasma is crucial. In this study, we evaluated the impact of social media on motivating blood donors to donate plasma without any compensation and the moderating effects of blood donation history on plasma donation.

METHODS AND MATERIALS

we allocated blood donors (n = 501) to intervention and control groups randomly. Participants in the intervention group got educational and motivational messages through a WhatsApp channel. Then, we followed up all participants for six months and registered the information of the plasma donation during this period.

RESULT

In the intervention group, 6.8% had returned to donate plasma, while this was 2% in the control group (p = 0.016, OR:3.59, 95%CI:1.3-9.89). Among regular blood donors in the intervention group, 17.86% had returned to donate plasma but, no regular donor returned to donate plasma in the control group (p = 0.055). In addition, 10.8% of donors who had academic education in the intervention group returned to donate plasma, although this was 2.54% in the control group (P = 0.0485).

CONCLUSION

Our findings suggest that the educational interventions have more effects on academically educated donors to motivate them to donate plasma.

Management of Wrong Blood Transfusion to an RhD Negative Woman in Labor

Blood transfusion is life-saving in massive hemorrhage. Before pre-transfusion tests with ABO and RhD typing results are available, O RhD negative packed red blood cell (PRBC) units are used without cross-matching in emergency. RhD negative girls and women of child-bearing age should always receive RhD negative blood transfusions to prevent RhD-alloimmunization because anti-D-related hemolytic disease of fetus and newborn (HDFN) can result in mild to severe anemia, and in a worst-case scenario death of an RhD positive fetus and/or newborn. However, "wrong blood to wrong patient" happens unintentionally. Here we report an emergency blood transfusion with one unit of RhD positive PRBCs to an RhD negative young woman when estimated blood loss was 2500 mL during delivery and surgical removal of retained placenta. Realizing the mistake, management with high dose anti-D immunoglobulin (Ig) was initiated to remove the RhD positive red blood cells (RBCs) from the patient's circulation. Such mitigation is recommended only for girls and women of child-bearing age. Follow-up was performed by flow cytometry until RhD positive RBCs were no longer detected. Ten months after the delivery, antibody screening was negative. However, we still do not know whether we managed to prevent RhD-alloimmunization.

Blood banking considerations in pediatric trauma

ABSTRACT

Transfusion of blood products to a hemorrhaging pediatric trauma patient requires seamless partnership and communication between trauma, emergency department, critical care, and transfusion team members. To avoid confusion and delays, understanding of blood banking principles and mutually agreed upon procedures and policies must be regularly updated as knowledge evolves. Because pediatric patients require specialized considerations distinct from those in adults, this brief review covers transfusion principles, policies, and procedures specific to the resuscitation of pediatric trauma patients.

Anti-D Alloimmunization After RhD Positive Red Cell Transfusion to Selected RhD Negative Patients

Transfusion of RhD positive red cells to RhD negative individuals is not routine transfusion practice for the fear of alloimmunization. Aim of this study was to prospectively evaluate rate of alloimmunization after transfusion of RhD positive red cells in RhD negative individuals and to assess delay in transfusion due to decision making. This was a prospective, observational study conducted from 2014 to 2018. All patients were followed up for a period of three months, at 3, 14, 45 and 90 days with antibody screening. In addition, patients who were immunosuppressed and alloimmunized were followed up at 6 months and one year. During the period of the study, there were a total of 57 RhD negative patients (52 males and five females) who received a mean of 4.42 ± 2.85 transfusions. Alloimmunization was detected in 8 (14.03%) patients at a mean interval of 25.63 ± 16.04 days. Anti-D was detected in seven and one patient developed anti-E alloantibody. Mean number of red cell units transfused in alloimmunized was 1.7 ± 0.26 while it was 5.4 ± 1.82 in non-alloimmunized group. There was no delay in providing units to these patients. The TAT was found to be 68 min. Rate of alloimmunization after transfusion of RhD positive red cells to RhD negative individuals was found to be 12.3%. In life saving conditions, RhD negative patients can be transfused RhD positive red cells without delay in decision making.

Rate of D-alloimmunization in trauma does not depend on the number of RhD-positive units transfused: The BEST collaborative study

BACKGROUND

Evidence indicates the life-saving benefits of early blood product transfusion in severe trauma resuscitation. Many of these products will be RhD-positive, so understanding the D-alloimmunization rate is important.

METHODS

This was a multicenter, retrospective study whereby injured RhD-negative patients between 18-50 years of age who received at least one unit of RhD-positive red blood cells (RBC) or low titer group O whole blood (LTOWB) during their resuscitation between 1 January, 2010 through 31 December, 2019 were identified. If an antibody detection test was performed ≥14 days after the index RhD-positive transfusion then basic demographic information was collected, including whether the patient became D-alloimmunized. The overall D-alloimmunization rate, and the rate stratified by the number of units transfused, were calculated.

RESULTS

Data were collected from nine institutions. Five institutions reported fewer than 10 eligible patients each and were excluded. From the remaining four institutions, all from the USA, there were 235 eligible patients; 77 (random effects estimate: 32.7%; 95% CI: 19.1-50.1%) became D-alloimmunized. Three of the institutions reported D-alloimmunization rates ≥38.6%, while the remaining institution's rate was 12.2%. In both random and fixed-effects models, the rate of D-alloimmunization was not significantly different between those who received one RhD-positive unit and those who received multiple RhD-positive units.

CONCLUSION

In this large, multicenter study of injured patients, the overall rate of D-alloimmunization fell within the range previously reported. The rate of D-alloimmunization did not increase as the number of transfused RhD-positive units increased. These data can help to inform RhD type selection decisions.

Recommendation for validation and quality assurance of non-invasive prenatal testing for foetal blood groups and implications for IVD risk classification according to EU regulations

BACKGROUND AND OBJECTIVES

Non-invasive assays for predicting foetal blood group status in pregnancy serve as valuable clinical tools in the management of pregnancies at risk of detrimental consequences due to blood group antigen incompatibility. To secure clinical applicability, assays for non-invasive prenatal testing of foetal blood groups need to follow strict rules for validation and quality assurance. Here, we present a multi-national position paper with specific recommendations for validation and quality assurance for such assays and discuss their risk classification according to EU regulations.

MATERIALS AND METHODS

We reviewed the literature covering validation for in-vitro diagnostic (IVD) assays in general and for non-invasive foetal RHD genotyping in particular. Recommendations were based on the result of discussions between co-authors.

RESULTS

In relation to Annex VIII of the In-Vitro-Diagnostic Medical Device Regulation 2017/746 of the European Parliament and the Council, assays for non-invasive prenatal testing of foetal blood groups are risk class D devices. In our opinion, screening for targeted anti-D prophylaxis for non-immunized RhD negative women should be placed under risk class C. To ensure high quality of non-invasive foetal blood group assays within and beyond the European Union, we present specific recommendations for validation and quality assurance in terms of analytical detection limit, range and linearity, precision, robustness, pre-analytics and use of controls in routine testing. With respect to immunized women, different requirements for validation and IVD risk classification are discussed.

CONCLUSION

These recommendations should be followed to ensure appropriate assay performance and applicability for clinical use of both commercial and in-house assays.

Incidence of anti-D alloimmunization in D-negative individuals receiving D-positive red blood cell transfusion: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

The transfusion of D-negative red blood cells (RBCs) to D-negative patients has been widely adopted to prevent anti-D alloimmunization, especially in women of childbearing age. Still, transfusion of D-positive RBCs to D-negative recipients is occasionally inevitable in practice, and the resulting incidence of anti-D in different D-negative groups of patients has not been well summarized.

MATERIALS AND METHODS

We searched the relevant literature using PubMed, Cochrane Library, and Embase databases from inception date to 30 September 2021. We looked for studies of anti-D occurring in D-negative recipients who received D-positive RBC transfusions. The anti-D incidence was summarized with 95% confidence intervals (CIs). Data with similar characteristics were combined using a random-effects model.

RESULTS

About 42 studies (2226 cases), which found anti-D, the exact volume of D-positive RBC transfused, and the follow-up time for anti-D detection, met the inclusion criteria. The pooled anti-D incidence was 64% (95% CI, range 55%-74%) in volunteers receiving small volumes of D-positive RBCs, 84% (95% CI, 74%-94%) in those receiving whole units, 26% (95% CI, 19%-32%) in mixed patients, 12% (95% CI, 8%-16%) in oncology patients, 27% (95% CI, 13%-40%) in trauma patients, 4% (95% CI, 0%-8%) in immune-compromised transplant patients, and 6% (95% CI, 1%-39%) in those with AIDS.

CONCLUSION

Compared with the high frequency of anti-D in healthy D-negative volunteers given D-positive RBCs, we found a lower rate of anti-D immunization in various D-negative patients and almost none in transplant and AIDS patients.

Anti-D alloimmunization in Rh(D) negative adults with severe traumatic injury

INTRODUCTION

Widely varying rates of alloimmunization associated with transfusing uncrossmatched RBC products to trauma patients as part of hemostatic resuscitation have been reported. We characterized the rates of RBC alloimmunization in our severely injured Rh(D) negative trauma population who received uncrossmatched Rh(D) positive RBC products.

METHODS

In a 10-year retrospective analysis to assess Rh(D) alloimmunization risks, Rh(D) negative adult trauma patients initially requiring uncrossmatched group O Rh(D) positive RBC products with either RBC units or low titer group O whole blood as part of massive transfusion protocol (MTP) activation were identified. Only those Rh(D) negative patients whose initial antibody screenings were negative were included. Duration of serologic follow-up from date of MTP activation to either date of anti-D detection or most recent negative antibody screening was calculated.

RESULTS

There were 129 eligible Rh(D) negative trauma patients identified. Median injury severity score was 25. Anti-D was detected in 10 (7.8%) patients after a median of 161.5 days; the median duration of serologic follow-up in those who did not have anti-D detected was 220 days. Patients who had anti-D detected were less severely injured and received fewer Rh(D) positive RBC products versus those who did not.

DISCUSSION

In our severely injured adult trauma patients with MTP activation requiring uncrossmatched group O Rh(D) positive RBC products, the rate of anti-D detection was low. Additional studies are necessary to determine generalizability of these findings and fully characterize alloimmunization risks in trauma patients with varying extents of injury.

Does Gender Matter: A Multi-Institutional Analysis of Viscoelastic Profiles for 1565 Trauma Patients With Severe Hemorrhage

BACKGROUND

Viscoelastic tests including thromboelastography (TEG) and rotational thromboelastometry (ROTEM) are being used in patients with severe hemorrhage at trauma centers to guide resuscitation. Several recent studies demonstrated hypercoagulability in female trauma patients that was associated with a survival advantage. The objective of our study was to elucidate the effects of gender differences in TEG/ROTEM values on survival in trauma patients with severe hemorrhage.

METHODS

A retrospective review of consecutive adult patients receiving massive transfusion protocol (MTP) at 7 Level I trauma centers was performed from 2013 to 2018. Data were stratified by gender and then further examined by TEG or ROTEM parameters. Results were analyzed using univariate and multi-variate analyses.

RESULTS

A total of 1565 patients were included with 70.9% male gender (n = 1110/1565). Female trauma patients were older than male patients (43.5 ± .9 vs 41.1 ± .6 years, P = .01). On TEG, females had longer reaction times (6.1 ± .9 min vs 4.8 ± .2 min, P = .03), increased alpha angle (68.6 ± .8 vs 65.7 ± .4, P < .001), and higher maximum amplitude (59.8 ± .8 vs 56.3 ± .4, P < .001). On ROTEM, females had significantly longer clot time (99.2 ± 13.7 vs 75.1 ± 2.6 sec, P = .09) and clot formation time (153.6 ± 10.6 sec vs 106.9 ± 3.8 sec, P < .001). When comparing by gender, no difference for in-hospital mortality was found for patients in the TEG or ROTEM group (P > .05). Multivariate analysis showed no survival difference for female patients (OR 1.11, 95% CI .83-1.50, P = .48).

CONCLUSIONS

Although a difference between male and females was found on TEG/ROTEM for certain clotting parameters, no difference in mortality was observed. Prospective multi-institutional studies are needed.

Rate of RhD-alloimmunization after the transfusion of RhD-positive red blood cell containing products among injured patients of childbearing age: single center experience and narrative literature review

OBJECTIVES

To determine the rate of RhD-alloimmunization in injured RhD-negative patients in the age range of childbearing potential who were transfused with at least one unit of RhD-positive red blood cells (RBC) or low titer group O whole blood (LTOWB).

METHODS

Injured RhD-negative patients between the ages of 13-50 at an American Level 1 trauma center who were transfused with at least one unit of RBCs or LTOWB during their resuscitation and who had an antibody detection test performed at least 14 days afterwards were included.

RESULTS

Over a 20-year period, 96 study-eligible patients were identified, of which 90/96 (93.8%) were male. The median age of these 96 patients was 33 (5th-95th percentiles: 19-49) years. The majority of these patients (71/96, 74.0%) had an injury severity score (ISS) greater than 15. Overall, 41/96 (42.7%; 95% CI: 32.7%-53.2%) of these patients became alloimmunized after receipt of a median of 3 (5th-95th percentiles: 1-35) units of RhD-positive RBCs and/or LTOWB. There was no association between receipt of leukoreduced RBCs or receipt of LTOWB and the RhD-alloimmunization rate.

DISCUSSION

The rate of RhD-alloimmunization in this study was at the higher end of rates that have been reported. None of the previous studies focused exclusively on trauma patients in the childbearing age range.

CONCLUSION

The 42.7% rate of RhD-alloimmunization in a predominantly male trauma population could probably be extrapolated to women in the same age range when estimating their risk of RhD-alloimmunization following RhD-positive transfusion.