Negative Red Blood Cells Research Articles

Genotyping for Weak and Partial D Rh Status to Optimize Usage of Limited Blood Supplies

Abstract Introduction The Rh antigen group, expressed on erythrocytes and encoded by highly polymorphic RHD and RHCE genes on chromosome 1 (1p36-p34), is notable in transfusion medicine due to its high polymorphism, strong immunogenicity and ability to cause hemolytic transfusion reactions in patients and hemolytic disease of the fetus and newborn (HDFN). The D antigen specifically contains multiple epitopes with variations that include decreased expression (weak D) or loss of certain epitopes (partial D) which expose patients to risk of alloimmunization depending on the subtype of the Rh(D) antigen. Hence, serologic weak D testing followed by molecular testing is not performed except for donors testing negative for Rh(D) antigen and newborns typing negative for Rh(D) and born to Rh(D) negative mothers. Given the current shortages of blood supplies, understanding patients’ genotypes in the context of weak or partial D-typing and risk of alloimmunization can be essential in the management of increasingly limited supplies of red blood cell (RBC) units. Objective To further characterize patients that initially type negative for Rh(D) but positive for weak D with molecular testing to investigate risk of alloimmunization, retype the Rh(D) and avoid unnecessary use of Rh(D) negative RBC units during critical shortages of RBC units. Methods We collected the results of ABO/Rh(D) typing for patients with negative Rh(D) testing but positive weak D test over a period of four weeks in December 2023 and had D-variant molecular testing performed by a reference laboratory. Initial serologic ABO/Rh(D) was performed in tube followed by weak D testing by indirect Coombs test in tube. Results The total number of patients who initially tested negative for Rh(D) but positive (weak to +4) for weak-D was three patients. Two patients showed a probable genotype of RHD*01W.1 (RHD* weak type 1, 809T>G (V270G)) homozygous which indicated the presence of weak D+ type 1. Patients with weak D+ type 1 can receive Rh(D) positive red cell units, and they are not at risk of alloimmunization and developing anti-D. The third patient showed a probable genotype RHD*DVI type 2 homozygous (lack of Rh(D) exons 4 through 6) and indicated the presence of partial D antigen. Patients with partial D antigen should receive RH(D) negative red cell units as they are at risk of alloimmunization and developing anti-D. Conclusions Although the vast majority of Transfusion Medicine services do not perform the serologic weak D test with reflex to molecular testing, characterizing patients who test negative with initial serologic Rh(D) testing with serologic and molecular D-tests may aid in retyping the Rh(D) of patients during critical shortages, particularly for patients with ABO blood group O.

Red Blood Cell Aliquoting: Improving O Negative Red Blood Cell Utilization in Neonate and Pediatric Inpatients at UC Davis Medical Center

Abstract Introduction/Objective UC Davis Medical Center (UCDMC) is the Sacramento region’s only level 1 adult and pediatric trauma center. It serves a 65,000 square mile area that includes 6 million residents from 33 counties across Northern and Central California. Nearly 7000 patients are transfused annually at UCDMC. Blood supply restrictions, especially on group O negative red blood cells (RBCs), escalated by the COVID-19 pandemic, posed significant patient safety risk. We sought to mitigate this risk by employing restrictive O negative RBC transfusions as recommended by AABB Choosing Wisely, through ABO matched small volume transfusions in neonate and pediatric patients. Methods/Case Report We conducted monthly audits starting in January 2021 to identify trends in O negative RBC use at UCDMC. We partnered with our blood supplier, American Red Cross (ARC), to modify hospital blood inventory. In 2022, we implemented the RBC aliquoting procedure using AS-3 RBCs to facilitate ABO matched small volume transfusions in neonates and children to conserve O negative blood supply. We reviewed regulatory standards, developed standard operating procedures, performed extensive technical validations, and worked with IT to enhance laboratory information system for product manufacturing, labeling, and traceability. We developed education documents for physicians, other providers, nurses, and transfusion services staff including sustainable competency and training. We conducted audits post implementation to measure goal performance in Q4 of FY22, compared to pre- implementation baseline data from Q1 of FY22. Results (if a Case Study enter NA) N/A Conclusion We achieved 57% reduction in O negative RBC utilization post implementation of the RBC aliquoting procedure in Q4 of FY22. Overall O negative RBC use trend at UCDMC improved with a 58% reduction between January 2021 to December 2022. Subsequent reduction of orders was achieved.We conclude that ABO matched RBC aliquot transfusion in neonates and pediatrics is an effective laboratory practice to reduce O negative RBC usage.

Recent RhIG Administration Does Not Interfere with the Rosette Test

Abstract Introduction/Objective Administration of Rh immune globulin (RhIG) is indicated mid-gestation (28 weeks) and after delivery to prevent Rh D sensitization in Rh D negative women. Women with sporadic prenatal care may not receive the first dose at 28 weeks, and may end up receiving their first dose closer to delivery. The rosette test (RT) is a rapid screen for fetomaternal hemorrhage (FMH) that uses an IgM anti-D antibody to detect fetal Rh D positive red blood cells (RBC) in maternal circulation. It is not currently known if or how recent administration of RhIG prior to performance of a RT may interfere with RBC agglutination and test results. Methods/Case Report To approximate mixing of fetal Rh D positive RBC with maternal Rh D negative RBC during FMH, 2% volume of Rh D positive RBC from fetal cord and adult donor samples were spiked into Rh D negative RBC. These mixtures were then incubated with a physiologic concentration of RhIG to occupy all Rh D antigen sites on the Rh D positive cells prior to performing the RT. Results (if a Case Study enter NA) Addition of Rh D positive RBC and RhIG to Rh D negative RBC did not affect rosette formation. Rh D negative cells had 0 rosettes/LPF. Rh D negative cells spiked with 2% Rh D positive adult donor and fetal cord RBC by volume produced an average of 9.8 rosettes/LPF (SD: 2.8) and 11.2 (SD: 3.3), respectively. Addition of a physiologic concentration of RhIG to the spiked Rh D positive adult donor and fetal cord RBC produced an average of 13.0 rosettes/LPF (SD: 2.5) and 11.2 rosettes/LPF (SD: 2.6), respectively. Conclusion Incubation of Rh D positive RBCs with physiologic concentration of RhIG does not affect the rosette test. Clinicians and laboratorians should be reassured that the rosette test continues to be an accurate way to quantitate FMH after recent RhIG administration.

Survey of intrauterine red blood cell (RBC) transfusion practices in the United States.

A paucity of data exists about the current practice of fetal red blood cell (RBC) transfusion in the United States (US). This investigation describes intrauterine transfusion (IUT) RBC product selection and processing practices at different US institutions. A transfusion medicine and maternal-fetal medicine (MFM) team designed a survey to interrogate and characterize RBCs utilized for IUT. This survey was distributed to seventy US institutions with fetal treatment centers (October 2020-April 2021) identified through the NAFTNet (North American Fetal Therapy Network). Thirty-seven institutions responded (response rate 53%, 37/70), but five were excluded for not performing IUTs. Most (84%; 27/32) performed 1-24 IUTs annually; two performed >50 IUTs/year. Group O, Rh(D) negative RBC units were always used by 66% (21/32), and 75% (24/32) provided hemoconcentrated RBCs by washing (17/24) or dry packing (6/24). Overall, 66% (21/32) targeted a hematocrit ≥75%. Fifty percent provided both leukocyte-reduced and CMV-negative RBC units. Irradiation of RBC units was performed within 6 h of issue at 63% (20/32) of sites. Most (81%, 26/32) used RBC units at <7 days of age after collection, 56% (18/32) always provided washed RBC units, while 19% (6/32) issued washed RBC only if fresh units are unavailable. Implicated maternal RBC alloantibodies were matched for 78% (25/32) of the time. The transfused volume was universally determined by the MFMs. Heterogeneity and lack of standardization exist in RBC product selection and special processing steps for IUTs in the US. Hence, the establishment of a consensus to standardize IUT protocols is needed.

Safety of Uncrossmatched ABO-Compatible RBCs in Alloimmunized Patients with Bleeding: Data from Two Decades: Results of a Systematic Analysis in 6,109 Patients

Introduction: Uncrossmatched ABO-compatible red blood cells (RBCs) are generally recommended in patients with life-threatening massive bleeding. There is little data regarding RBC transfusion when patients are transfused against clinically significant alloantibodies because compatible RBCs are not immediately available. Methods/Patients: All patients reviewed in this study (n = 6,109) required emergency blood transfusion and were treated at the Charité – Universitätsmedizin Berlin between 2001 and 2015. Primary uncrossmatched O Rh(D)-positive or -negative RBC units were immediately transfused prior to complete regulatory serological testing including determination of ABO group, Rhesus antigens, antibody screening, and crossmatching. Results: Without any significant change in the protocol of emergency transfusion of RBCs, a total of 63,373 RBC units were transfused in 6,109 patients. Antibody screening was positive in 413 patients (6.8%), and 19 of these patients received RBC units against clinically significant alloantibodies. None of these patients appeared to have developed significant hemolysis, and only one patient with anti-D seems to have developed signs of insignificant hemolysis following the transfusion of three Rh(D)-positive units. One patient who had anti-Jk^a received unselected units and did not develop a hemolytic transfusion reaction. Conclusion: Transfusion of uncrossmatched ABO-compatible RBCs against alloantibodies is highly safe in patients with life-threatening hemorrhage.

Clinical and Economic Impact of Red Blood Cell Antigen Alloimmunization on Patients with Hereditary Hemorrhagic Telangiectasia

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare autosomal dominant disorder characterized by the presence of arteriovenous malformations which lead to repeated bleeding episodes for which Red Blood Cell (RBC) transfusions may be required. Previous research has shown that this patient population presents with high rates of alloimmunization against RBC antigens (15.29%) (Zheng Transfusion. 2018;58(3):775-780). However, the impact of such complications on clinical and economic outcomes has not been assessed previously. The present study aims to quantify the impact of alloimmunization on clinical outcomes and healthcare costs among HHT patients in a hospital setting.A cross-sectional study of alloimmunized and non-alloimmunized patients using the Premier Hospital chargemaster dataset from January 2015 to June 2019 was performed. Alloimmunization was defined based on the presence of antiglobulin crossmatch and RBC antibody identification laboratory codes in patient medical records. In order to assess the accuracy of this method of identification, the alloimmunization rates among discharges for patients diagnosed with HHT and myelodysplastic syndrome (MDS) for 2018 were extrapolated to the whole country and compared to reports in the literature (Zheng Transfusion. 2018;58(3):775-780, Singhal Haematologica. 2017;102(12):2021-2029). Consistent results were shown, 16.8% vs 15.3% and 11.5% vs. 11% for the HHT and MDS discharges, respectively.Alloimmunized and non-alloimmunized groups were matched for sex, age, admission date, and visit type (outpatient vs. inpatient). Diagnosis of HHT was defined using ICD-10 code I78.0. Cost per discharge for outpatient and inpatient visits, hospital and intensive care unit (ICU) length of stays (LoS), and inpatient mortality were both cases and controls. Bivariate comparisons were performed assuming a two-tailed test of significance and α level of 0.05 and multivariable regression models adjusting for diagnosis-related groups (incidence ≥1%) were performed.A total of 783 alloimmunized HHT cases were matched to 6,744 non-alloimmunized controls. Mean (SD) age was 65.7 (10.9) years for the alloimmunized (cases) and 59.4 (16.3) for the non-alloimmunized (controls), and slightly more than half of the population included in both groups were females (53.0% and 54.0% for the alloimmunized and non-alloimmunized groups, respectively).Outpatient visits were more common than inpatient admissions in both groups (52.6% and 71.4% of cases and controls, respectively albeit inpatient admissions were less common in both control groups (47.4% vs. 28.6%). Most common diagnoses leading to inpatient admission in both groups were disorders of the circulatory system (16.1% and 8.0%, respectively), followed by blood disorders for the alloimmunized group (9.8%) and disorders of the digestive system for the non-alloimmunized group (3.6%).Alloimmunized HHT patients presented with 22% longer hospitalizations (6.1 vs 7.3 days; p=0.0001) and 54% longer ICU stays (4.7 vs 7.2 days; p=0.0146), as well as a 40% increased likelihood of being admitted to the ICU. Inpatient mortality was higher among the alloimmunized population although it did not reach statistical significance (Odds Ratio: 1.53 [0.79; 2.96]; p=0.2092). Overall 12 (3.23%) and 59 (3.1%) deaths were reported for the alloimmunized and non-alloimmunized patient population, respectively. Median costs per discharge were significantly higher both for inpatient ($1,461; p=0.0202) and outpatient ($377; p<0.0001) visits within the alloimmunized population (Table 1).Presence of alloantibodies was associated with significantly worse clinical outcomes, increased healthcare resource use and higher costs within HHT patients. The increased prevalence of alloimmunization within the HHT population is not yet fully understood, and this study was not designed to determine whether prophylactic antigen matching would prevent alloimmunization in the HHT population. Further studies assessing the use of preventive strategies such as prophylactic antigen matching to prevent alloimmunization and its clinical and economic consequences could help determine whether antigen negative RBC units should be preferentially distributed to HHT patients. [Display omitted] DisclosuresGehrie: Grifols SSNA: Consultancy, Honoraria. Viayna: Grifols S.A.: Current Employment. Blanchette: Grifols SSNA: Consultancy; Novo Nordisk Inc.: Current Employment. Meny: Grifols SSNA: Current Employment. Noumsi: Grifols SSNA: Current Employment. Huber: Grifols SSNA: Current Employment. Runken: Grifols SSNA: Current Employment.

Red Cell Alloimmunization Is Associated with Higher Treatment Costs and Poor Health Outcomes Among Hemoglobin S-Beta Thalassemia Patients

Hemoglobin S (HbS) beta thalassemias (thal) are types of sickle cell disease (SCD) that result from the inheritance of one HbS gene and one β thalassemia gene. Red Blood Cell (RBC) alloimmunization is believed to be a major complication of transfusion therapy for HbS-thal patients. Indeed, among SCD patients generally, alloimmunization not only complicates the procurement of blood, but can also lead to life threatening delayed hemolytic transfusion reactions, and can be associated with a host of negative health outcomes including a higher risk of death. It is generally accepted that some alloimmunization events can be prevented via donor-recipient antigen matching, although this strategy is associated with higher costs and utilization of scarce resources (i.e.. antigen negative RBC units). The present study aimed to assess the clinical and economic implications of alloimmunization in HbS-thal patients.The Premier Hospital chargemaster dataset was used to perform a cross-sectional study matching alloimmunized and non-alloimmunized patients based on sex, age, date of admission, and type of visit (outpatient vs. inpatient). All outpatient and inpatient discharges from Jan 2015 to Jun 2019 were included in the study. Because there is not a specific laboratory code to designate alloimmunization, presence of both “antiglobulin crossmatch” and “RBC antibody identification” codes in a record was used as a surrogate for alloimmunization. Accuracy of this approach was validated by comparing the frequency of these codes among the hereditary hemorrhagic telangiectasia (HHT) and myelodysplastic syndromes (MDS) populations within the Premier dataset to the reported rates of alloimmunization for these entities in the medical literature (Zheng Transfusion. 2018;58(3):775-780, Singhal Haematologica. 2017;102(12):2021-2029). This comparison predicted a 16.8% alloimmunization rate in the HHT population (similar to the 15.3% reported in the literature) and an 11.5% alloimmunization prevalence in the MDS population (similar to the 11% reported in the literature).HbS-thal patients were identified based on diagnostic coding (ICD-10 code D57.4). Demographic, clinical and billing characteristics were retrieved. Cost per outpatient and inpatient discharge, hospital and intensive care unit (ICU) length of stay (LoS) and inpatient mortality were assessed for both alloimmunized and non-alloimmunized HbS-thal patients. Bivariate comparisons were performed, assuming a two-tailed test of significance and an α level of 0.05. Multivariable regression models adjusting for diagnosis-related groups with ≥1% incidence were performed.This approach permitted a total of 999 discharges corresponding to alloimmunized HbS-thal patients (cases) to be matched to 550 HbS-thal controls. Mean (SD) age was 35.1 (18.8) and 30.1 (18.6) for cases and controls, respectively. The percentage of females was slightly higher within the alloimmunized group (63.66% vs. 57.45%), and higher rates of inpatient visits were observed for the alloimmunized population compared to controls (67.9% vs. 33.1%).The multivariate models showed that alloimmunized HbS-thal patients presented significantly worse economic and clinical outcomes compared to their non-alloimmunized controls through all variables assessed. Median cost per discharge was $5,313 (p<0.0001) higher for alloimmunized inpatients and $1,014 (p<0.0001) higher for alloimmunized outpatients, compared to non-alloimmunized controls. Alloimmunized HbS-thal patients also experienced a 63% increase in hospital LoS (4.5 vs 7.4 days;; p<0.0001) and nearly over a 2.5-fold increase in ICU LoS (4.2 vs 10.0 days; p=0.0257). Alloimmunization in this population was also associated with a 3-fold increased risk of admission to intensive care (p=0.0032), longer stays in the ICU (p-0.0257), and a 3-fold increase in inpatient death (p<0.0001) (Table 1).The present study reveals that alloimmunization is associated with significantly longer hospitalizations and ICU stays, higher risk of ICU admission, greater inpatient death, and higher healthcare costs among patients with ICD-10 diagnosis of HbS-thal. These data seem to support the incremental costs and resource allocation decisions required to provide prophylactic antigen matching to HbS-thal patients, in an effort to diminish the risk of alloimmunization. [Display omitted] DisclosuresGehrie: Grifols SSNA: Consultancy, Honoraria. Viayna: Grifols S.A.: Current Employment. Blanchette: Grifols SSNA: Consultancy; Novo Nordisk Inc.: Current Employment. Meny: Grifols SSNA: Current Employment. Noumsi: Grifols SSNA: Current Employment. Huber: Grifols SSNA: Current Employment. Runken: Grifols SSNA: Current Employment.

Longer Hospitalizations, Increased Inpatient Mortality and Costs Are Associated with Alloimmunization Among Patients with Myelodysplastic Syndromes

Red Blood Cell (RBC) transfusions remain an important part of the management of anemia caused by myelodysplastic syndromes (MDS). Almost 90% of patients diagnosed with MDS require at least one RBC transfusion and 30%-45% require chronic transfusions (Singhal Haematologica. 2017;102(12):2021-2029). Importantly, it is estimated that 11% of MDS patients form alloantibodies as a result of RBC transfusions. Despite this relatively high alloimmunization rate, MDS patients are almost never prophylactically transfused with RBCs from antigen-matched donors, a strategy which has been shown to reduce the incidence of alloimmunization among patients with sickle cell disease, but which also increases costs and utilizes a limited resource (antigen negative RBCs). Herein, we present the economic and clinical burden of RBC alloimmunization in MDS patients, in order to better inform decision making regarding prophylactic RBC antigen matching.A cross-sectional study using the Premier Hospital chargemaster dataset was performed. All outpatient and inpatient discharges from January 2015 to June 2019 were included. MDS was defined using ICD-10 code D.46. Because there is no diagnosis code for alloimmunization, alloimmunized patients were identified based on the presence of antiglobulin crossmatch (CXM) and RBC antibody identification (RAI) codes in Premier records. This approach was validated by comparing the published rate of alloimmunization observed in patients diagnosed with MDS as well as hereditary hemorrhagic telangiectasia (HHT; another population with a relatively high alloimmunization rate) to the prevalence of both CXM and RAI codes in the Premier dataset during 2018. The comparison showed that our approach successfully modeled the published alloimmunization rates in HHT (16.8% vs 15.3%) and MDS (11.5% vs 11%) (Zheng Transfusion. 2018;58(3):775-780, Singhal Haematologica. 2017;102(12):2021-2029).Demographic, clinical, and billing characteristics were gathered. Total cost per discharge, hospital and intensive care unit (ICU) length of stay, and inpatient mortality, were calculated for both study groups and compared. Bivariate comparisons were performed, assuming a two-tailed test of significance and an α level of 0.05. Multivariable regression models adjusting for sex, age, admission date, visit type (outpatient vs. inpatient) type of MDS based on the World Health Organization (WHO) classification and diagnosis-related groups (DRG) with an incidence ≥1% of inpatient visits were performed.Overall, 179,819 MDS patient encounters were identified. Of these, 11,948 were alloimmunized and 167,871 were not alloimmunized (Table 1). When assessing incremental economic and clinical outcomes for the alloimmunized MDS population, multivariate models showed that alloimmunization led to significantly worse economic and clinical outcomes through all variables assessed (Table 2). The incremental median cost per inpatient and outpatient visit for the alloimmunized population were $2,829 (p<0.0001) and $630 (p<0.0001) higher, respectively. Alloimmunized patients had significantly longer inpatient hospitalizations (7.2 vs 8.2 days; p<0.0001) as well as longer ICU stays (4.4 vs 6.8 days; p<0.0001). Alloimmunized)A patients also encountered a 38% increased risk of being admitted to intensive care, and a 30% higher risk of inpatient mortality.This analysis discloses that alloimmunization is associated with higher healthcare costs and worsened clinical outcomes in the MDS population. Further work is needed to clarify whether alloimmunization is causally related to these outcomes, or whether alloimmunization is incidentally more common among patients with worse disease. The present study was not designed to assess the effectiveness of prophylactic antigen matching in the prevention of alloimmunization in the transfused MDS population, and further work is needed to confirm the findings presented herein. However, decisions regarding provision of antigen-matched RBCs to MDS patients should consider the potential for downstream consequences of alloimmunization. [Display omitted] DisclosuresGehrie: Grifols SSNA: Consultancy, Honoraria. Viayna: Grifols S.A.: Current Employment. Blanchette: Grifols SSNA: Consultancy; Novo Nordisk Inc.: Current Employment. Meny: Grifols SSNA: Current Employment. Noumsi: Grifols SSNA: Current Employment. Huber: Grifols SSNA: Current Employment. Runken: Grifols SSNA: Current Employment.

Anti-Rh alloimmunization after trauma resuscitation

The AABB recently posted a bulletin (19-02) regarding their recommendations for the use of group O red blood cells (RBCs) during trauma. Though group O Rh(D)-negative RBC units are considered the ‘safest’, the demand of such units often exceeds the supply. Therefore, O Rh(D)-positive units are often used during the first parts of a massive transfusion protocol (MTP) or patients with particularly severe hemorrhage are switched over from O Rh(D)-negative to O Rh(D)-positive RBC units in order to preserve the O Rh(D)-negative supply.In light of these limitations, it is important to understand the risk of such policies to the patient. The reported risk of alloimmunization after exposure to Rh(D)-positive RBCs ranges widely from 3 to 70%. In response, we performed a retrospective review of 1,198 patients in our institution that had a MTP activation due to trauma. Of those patients, we focused on Rh(D)-negative patients that received at least 1 unit of Rh(D)-positive RBCs. Seventy-two patients met the criteria for inclusion, accounting for 6% of the total population.Of the 72 Rh(D)-negative patients, we identified 17% that formed new Rh group antibodies after exposure to Rh(D)-positive RBCS. All 10 of our alloimmunized patients (two of which were females of childbearing age) formed anti-D, while 3 patients also formed either anti-E or anti-C. Since this was a retrospective review, we did not perform repeated antibody screens for the entire study period, but did review all records for the entire period. We did note that we were more likely to detect an novel alloantibody if more antibody screens were performed during the patient’s initial stay and during follow-up visits.We conclude that providing Rh(D) negative patients Rh(D) positive RBC units is not without risk and policies regarding such provisions should be carefully considered. As RBC shortages continue to be a part of daily practice, such issues may continue to be a challenge for the blood bank community.

A suspected delayed hemolytic transfusion reaction mediated by anti-Joa

A 32-year-old African-American woman with a history of sickle cell disease presented for surgical evaluation of left total hip arthroplasty due to avascular necrosis of the femoral head. In anticipation of a complex orthopedic procedure, pre-surgical blood work was ordered. The patient's Fenwal blood sample typed as group O, D+. Although the patient had a history of anti-Fya, the antibody identification was inconclusive, so the workup was sent to a reference laboratory. The patient was last transfused with red blood cells (RBCs) 2 years earlier, but had no history of transfusion reactions. Due to surgery, the patient's hemoglobin (Hb) decreased from 10.2 g/dL (preoperative) to 8.6 g/dL (postoperative). One unit of weakly crossmatch-incompatible Fy(a-), C-, E-, K-, and sickle cell hemoglobin S (HbS)-negative RBCs was transfused without incident, and the patient was discharged. Several days later, the reference lab reported two new specificities, anti-Joa and anti-Jkb. Fortunately, the transfused RBC unit was Jk(b-). Therefore, the crossmatch incompatibility was attributed to anti-Joa, which targets a high-prevalence antigen found in 100 percent of most populations. Two weeks after discharge, the patient returned in sickle vaso-occlusive pain crisis. The patient was clinically stable, but her Hb was 6.7 g/dL. One unit of Fy(a-), Jk(b-), C-, E-, K-, HbS- RBCs, which was weakly crossmatch-incompatible, was transfused. The following day, her Hb was unchanged, lactic acid dehydrogenase increased from 951 to 2464 U/L, potassium increased from 3.7 to 4.6 mEq/L, creatinine increased from 0.60 to 0.98 mg/dL, and the patient developed a 38.4°C fever. These findings are consistent with a delayed hemolytic transfusion reaction (DHTR), mediated by anti-Joa, occurring 2 weeks after the first RBC transfusion. Further care could not be provided because the patient left the hospital against medical advice. The purpose of this case study is to report findings consistent with a DHTR attributed to anti-Joa, an antibody with relatively unknown clinical significance.

Activity, specificity, and titer of naturally occurring canine anti-DEA 7 antibodies.

The reported prevalence of naturally occurring anti-dog erythrocyte antigen (DEA) 7 antibodies in DEA 7-negative dogs is as high as 50%. Characterization of these antibodies may better define their importance in canine transfusion medicine. We determined in vitro activity, specificity, and titer of anti-DEA 7 antibodies in DEA 7-negative dogs. Plasma samples from 317 DEA 7-negative dogs were cross-matched with DEA 7-positive red blood cells (RBCs) using gel column technology. Agglutination occurred with DEA 7-positive RBCs but not with DEA 7-negative RBCs in 73 samples (23%), which were hence classified as containing anti-DEA 7 antibodies. These samples were evaluated for hemolytic and agglutinating activity, strength of agglutination, and antibody specificity and titers. All samples showed agglutination but none showed hemolysis. Gel agglutination was graded as 1+ for 20 samples (27%), 2+ for 49 samples (67%), 3+ for 4 samples (6%); no samples were graded 4+. The agglutination titer was <1:2 for 51 samples (73%), 1:2 for 13 samples (19%), 1:4 for 4 samples (5%), and 1:8 for 2 samples (3%). Of 16 samples treated with 2-mercaptoethanol, 11 samples (69%) contained only IgM, 4 samples (25%) exhibited only IgG activity, and 1 sample (6%) had both IgG and IgM activity. Low titers of warm, weakly agglutinating, mostly naturally occurring IgM anti-DEA 7 antibodies were found in 23% of DEA 7-negative dogs. The presence of naturally occurring anti-DEA 7 antibodies suggests that cross-matching of canine blood recipients is advisable, even at first transfusion, to minimize delayed transfusion reactions.

74 - Superior Red Blood Cell Generation From Human Pluripotent Stem Cells via a Novel Microcarrier Based Embryoid Body Platform

In vitro generation of red blood cells (RBCs) from human embryonic stem cells (hESC) and human induced pluripotent stem cells (hiPSC) appears to be a promising alternate approach to circumvent shortages in donor-derived blood supplies for clinical applications. Conventional methods for hematopoietic differentiation of hESC and iPSC rely on embryoid body (EB) formation and/or co-culture with xenogeneic cell-lines. However, these current methods are not amenable for scale-up and face obstacles for clinical translation due to the use of xenogeneic materials. Here we report the development of a serum-free and chemically defined platform using recombinant human Laminin-521 coated microcarriers for pluripotent stem cell expansion and hematopoietic differentiation of hESC and hiPSC. Improved survival and better quality EBs generated with the microcarrier-based method resulted in at least a 6-fold improvement in hemangioblast expansion, potentially culminating in a 80-fold improvement in the yield of RBC generation as compared to a conventional EB-based method. Using the improved microcarrier-based differentiation protocol, we demonstrated successful differentiation of O-negative (Rhesus factor D negative) RBCs from donor hiPSC generated from finger-prick blood. Universal donor RBCs (blood type O-RhD negative) could prove to be extremely useful for future cell therapy applications such as emergency blood transfusions and for treating poly-immunized patients with recurrent transfusion needs. Thus, our microcarrier-based differentiation platform could prove to be an appealing strategy for future scale-up of hESC and hiPSC culture and for hematopoietic differentiation under defined conditions for large-scale generation of universal donor RBCs.

Blood banks meet the paradox of Gabriel's Horn: what are the options to maintain supply as demand decreases?

Blood services worldwide have observed a decline in the demand for red blood cells (RBC). Despite this general decline, the demand profile has changed significantly with the demand for O D negative RBCs being maintained; whereas B D positive and AB D positive RBC demand has been reduced. In 2015, the blood type O D negative was seen in 6·3% of the combined first time donors among the five American Blood Centres involved in this study and 7·4% of first time Australian donors in 2014/2015, whereas O D negative distributions accounted for 10·5% of all red cell units issued by the American centres and 13·9% by the Australian centres. Inventory can therefore be of sufficient overall quantity but may not be adequate for the demand for units with specific blood types. Recruitment of new donors may need to become more targeted and/or financial or inventory control measures could also be required to ensure inventory matches demand. Blood Services will need to consider the available options in order to ensure that sufficiency of supply is secure and the donor panel is optimised to meet the new demand paradigm.

Evaluation of the RBC Pig-a assay and the PIGRET assay using benzo[a]pyrene in rats

The red blood cell (RBC) Pig-a assay has the potential to detect the in vivo mutagenicity of chemicals. Recently, use of the Pig-a assay with reticulocytes (the PIGRET assay) reportedly enabled the in vivo mutagenicity of chemicals to be detected earlier than using the RBC Pig-a assay. To evaluate whether the PIGRET assay is useful and effective as a short-term test, compared with the RBC Pig-a assay, we performed both assays using benzo[a]pyrene (BP), which is a well-known mutagen. BP was used to dose 8-week-old male rats orally at 0, 75.0, 150, and 300mg/kg administered as a single administration. Peripheral blood samples were then collected on days 0, 7, 14, and 28 after treatment and were used in both assays. In the treatment groups receiving 150mg/kg of BP or more, both the RBC Pig-a assay and the PIGRET assay detected the in vivo mutagenicity of BP. In the 300mg/kg treatment group, in which a significant increase in the mutant frequency (MF) was observed at all the sampling points using both the RBC Pig-a assay and the PIGRET assay, the reticulocyte (RET) Pig-a MF was higher than the RBC Pig-a MF on days 7 and 14 after treatment; nevertheless, the negative control RET Pig-a MF was comparable to the negative control RBC Pig-a MF. In addition, the RET Pig-a MF began to increase after day 7 and reached a maximum value on day 14 after treatment, whereas the RBC Pig-a MF increased continuously from day 7 until day 28 after treatment. These results indicate that the PIGRET assay has a higher sensitivity than the RBC Pig-a assay and that the PIGRET assay is useful for the earlier detection of the in vivo mutagenicity of chemicals, compared with the RBC Pig-a assay.

Quantitative blood group typing using surface plasmon resonance.

The accurate and reliable typing of blood groups is essential prior to blood transfusion. While current blood typing methods are well established, results are subjective and heavily reliant on analysis by trained personnel. Techniques for quantifying blood group antibody-antigen interactions are also very limited. Many biosensing systems rely on surface plasmon resonance (SPR) detection to quantify biomolecular interactions. While SPR has been widely used for characterizing antibody-antigen interactions, measuring antibody interactions with whole cells is significantly less common. Previous studies utilized SPR for blood group antigen detection, however, showed poor regeneration causing loss of functionality after a single use. In this study, a fully regenerable, multi-functional platform for quantitative blood group typing via SPR detection is achieved by immobilizing anti-human IgG antibody to the sensor surface, which binds to the Fc region of human IgG antibodies. The surface becomes an interchangeable platform capable of quantifying the blood group interactions between red blood cells (RBCs) and IgG antibodies. As with indirect antiglobulin tests (IAT), which use IgG antibodies for detection, IgG antibodies are initially incubated with RBCs. This facilitates binding to the immobilized monolayer and allows for quantitative blood group detection. Using the D-antigen as an example, a clear distinction between positive (>500 RU) and negative (<100 RU) RBCs is achieved using anti-D IgG. Complete regeneration of the anti-human IgG surface is also successful, showing negligible degradation of the surface after more than 100 regenerations. This novel approach is validated with human-sourced whole blood samples to demonstrate an interesting alternative for quantitative blood grouping using SPR analysis.

Presence Of CD55- and/Or CD59-Deficient Erythrocytes In Patients With Rheumatic Diseases: An Immune-Mediated Phenomenon?

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematopoietic stem cell disorder characterized by the somatic mutation of X-linked gene PIG-A, required for glycosylphosphatidylinositol (GPI)-anchor biosynthesis. This results in absent or decreased expression of all membrane proteins normally anchored by GPI - including CD55 and CD59 - in all circulating cells, leading to an unusual sensitivity of red blood cells (RBCs) to complement lysis and subsequently intravascular hemolysis and hemoglobinuria. According to the “dual pathogenesis” model, there is an immunoregulatory selection in favor of PNH clones to proliferate preferentially over normal hemopoiesis on a microenvironment of bone marrow failure. The incidence of “PNH-like” defect has been also demonstrated in many hematological diseases and on peripheral blood cells (PBC) of normal individuals.Complement system is recognized as having the potential to provoke severe impairment to host tissues. This is extensively demonstrated in autoimmune disease setting. Multiple regulatory and inhibitory enzymes, such as CD55 and CD59, known as complement regulatory proteins, adjust the progression of complement cascade at all levels, protecting the autologous cells. Complement activation and cytopenias have been associated with diminished CD55 and/or CD59 expression on PBC membranes. The aim of this study was to evaluate the presence of “PNH-like” red-cell populations in patients with rheumatic diseases and investigate possible correlations with clinical or laboratory parameters.CD55 and CD59 expression was evaluated in erythrocytes of 113 patients (94 females, 19 males, median age: 64 years) with rheumatic diseases: 38 with rheumatoid arthritis, 25 with systemic lupus erythematosus, 17 with Sjögren's syndrome, 7 with systemic sclerosis, 12 with vasculitis, 2 with dermatomyositis, 1 with ankylosing spondylitis and 11 with mixed connective tissue diseas, using the sephacryl-gel microtyping system, a semi-quantitative, inexpensive and simple method useful in screening “PNH-like” red-cell defect, with sensitivity comparable with that of flow cytometry. One hundred and twenty-one (121) healthy blood donors of similar age and gender and 10 patients with PNH were also studied, as control groups. In all samples with CD55- and/or CD59- negative RBCs, Ham and sucrose tests were also performed.Interestingly, the majority of patients (104/113, 92%) demonstrated “PNH-like” erythrocytic populations: 47 (41.6%) with concomitant deficiency of CD55 and CD59, 50 (44.2%) with isolated deficiency of CD55 and 6 (6.2%) with isolated deficiency of CD59. In healthy donors, only 2 (1%) had red cells with concomitant CD55/CD59 negativity and 3 (2%) with isolated CD55 or CD59 deficiency. “PNH-like” erythrocytic clones never surpassed 25% of the total red-cell population, while the most common proportion of deficiency for both antigens was 10%. All PNH patients exhibited simultaneous CD55/CD59 deficiency. Moreover, it should be high-lightened that we found an unprecedented relation between patients' hemoglobin (Hb) and CD55 expression on RBCs (rs= -0.205, p=0.029), while there was a significant difference (δ) when the mean concentration of Hb was compared between patients with normal expression of CD55 and those with deficiency of this protein (δ=-1.4534 g/dl, p=0.0151). There was no clinical or laboratory evidence of hemolysis in our patients. There was no association between the presence of “PNH-like” red-cell populations and cytopenias or specific treatment for the autoimmune disorder. Positive Ham and sucrose tests were found only in PNH patients.In conclusion, this study provides evidence supporting the presence of erythrocytes with CD55- and/or CD59- deficiency in patients with rheumatic diseases. The pre-existence of small PNH clones in the bone marrow of these patients, that acquire a survival advantage to proliferate against normal hemopoietic tissue and become detectable with our methodology, may be the underlying cause for this phenomenon. Moreover, it was demonstrated that CD55- deficiency on RBCs influences the levels of Hb, in these patients. Further studies, using molecular techniques, will be required, to clarify the exact pathophysiologic mechanisms for this deficiency. Disclosures:No relevant conflicts of interest to declare.

Red Blood Cell Alloimmunization and Hemolytic Disease of the Fetus and Newborn: New Approaches Using Animal Models

Women may become alloimmunized to foreign red blood cell (RBC) antigens after exposure during transfusion or pregnancy/delivery. These alloantibodies can be detrimental to developing fetuses/neonates, with six in every 1000 pregnancies being affected by maternal alloantibodies. Despite being described more than 80 years ago, hemolytic disease of the fetus and newborn (HDFN) has few preventive or therapeutic options. Outside of antigen avoidance, the most effective maternal preventive therapy to date is Rh immune globulin. However, it targets just one of the more than 50 antigens implicated in HDFN, and its mechanism of action remains unknown. Furthermore, treatment options for affected fetuses are limited largely to intrauterine transfusions of antigen negative RBCs. With a decrease in HDFN cases due to Rh(D), KEL has emerged as one of the most widely implicated antigens. We now describe a transgenic murine model in which the human KEL antigen is expressed on murine RBCs, with clinical significance in both pregnancy and transfusion settings. Transgenic animals were generated with expression of the human KEL2 antigen (referred to herein as KEL) on their RBCs using a β-globin promoter. KEL expression was evaluated on fetal liver and bone marrow erythroid precursors, mature RBCs, and organs. C57BL/6 or MuMT females were bred with transgenic heterozygous KEL males. Maternal serum was collected during pregnancy and after delivery, with anti-KEL glycoprotein responses measured by flow cytometric crossmatch. Newborn pups were evaluated for KEL positivity, degree of anemia, and presence of maternal anti-KEL. Additionally, the effect of anti-KEL alloantibodies on fetal RBC precursors was evaluated at multiple stages of gestation. Lastly, females alloimmunized through pregnancy were transfused with incompatible KEL RBCs labeled with a lipophilic dye, and females alloimmunized through transfusion were bred with KEL males. Transgenic mice have RBC specific expression of the KEL glycoprotein, with antigen detected on early and late RBC precursors in the fetal liver and bone marrow but not on any tested organ. Fetal/maternal blood exchange was maximally detected after delivery, with the majority of mothers developing anti-KEL glycoprotein antibodies (IgM and all IgG subclasses) within weeks of delivery. All IgG subclasses of anti-KEL crossed the placenta and bound to RBC precursors and mature RBCs in developing KEL positive pups; KEL negative pups had positive indirect antiglobulin tests. Maternal anti-KEL glycoprotein titers increased with antigen exposure, with fewer KEL positive pups born during successive pregnancies to alloimmunized C57BL/6 but not MuMT females. Affected KEL positive pups were anemic, and some were stillborn and hydropic-appearing. As has been described in humans, maternal anti-KEL alloantibodies suppressed the development of fetal KEL RBC precursors at all levels of maturation. Additionally, newborn pups had a relative reticulocytopenia, with reticulocyte recovery within a week after birth. Multiparous alloimmunized females exhibited rapid clearance of transfused incompatible KEL RBCs, and females alloimmunized through KEL RBC transfusion also had pups affected by HDFN. To the best of our knowledge, this is the first animal model of HDFN in which pregnancy stimulates alloantibodies to a paternally derived RBC antigen, with these alloantibodies being clinically significant in both pregnancy and transfusion settings. The anti-KEL glycoprotein alloantibodies generated in this model have similar effects on murine RBCs as anti-KEL1 alloantibodies have on human RBCs. Such effects include suppression of erythropoiesis, fetal anemia, and even hydrops fetalis. This model thus provides a platform to study not only the induction, placental transfer, and consequences of maternal RBC alloantibodies, but also to investigate potential preventive therapies (including “KEL” immune globulin). Long-term translational goals of this work include minimizing the dangers of RBC alloantibodies to developing fetuses and neonates, through the development of targeted maternal immunomodulatory therapies. Disclosures:No relevant conflicts of interest to declare.

Crucial Role of Complement Receptor Type 1 On the Accumulation of Complement Component 3 On Erythrocytes in Patients with PNH Treated with Eculizumab

AbstractAbstract 988Paroxysmal nocturnal hemoglobinuria (PNH) is a hematologic disorder characterized by the clonal expansion of hematopoietic stem cells that are incapable of glycosylphosphatidylinositol (GPI)-anchor biosynthesis, due to an acquired somatic mutation in the PIGA gene. Affected progeny cells are deficient in all GPI-anchored surface proteins, including the complement regulators CD55 and CD59. Deficiency of CD55 and CD59 accounts for the intravascular hemolysis. Eculizumab is a humanized monoclonal antibody against complement component 5 (C5), thereby inhibiting terminal complement-mediated hemolysis. Eculizumab treatment has significantly reduced hemolysis and transfusion dependency, and improved anemia. However, the hematologic benefit varies considerably among patients. Lactate dehydrogenase levels remain slightly elevated and haptoglobin levels remain low in some patients suggesting residual low level hemolysis. Remarkable extravascular hemolysis mediated by C3 opsonization of PNH red blood cells (RBCs) in some patients with PNH receiving eculizumab has been reported (Blood 113,4094,2009). Complement receptor type 1 (CR1) has a crucial role in dissociation of C3/C5 convertases which activate C3. To explain the mechanism of extravascular hemolysis mediated by C3 opsonization in patients with PNH receiving eculizumab, the kinetics of CR1 and C3 in six patients with PNH (UPN2 to 7) who are treated with eculizumab at Osaka University Hospital were analyzed (Table1).We first confirmed that patients with PNH (UPN2 to 5) being treated with eculizumab had C3 positive RBCs with variable degree (1.8%-39.8%) and C3 positive RBCs were solely identified within CD59 negative RBCs, whereas healthy controls had only CD59 positive/C3 negative RBCs and untreated patients had both CD59 positive and negative/C3 negative but no C3 positive RBCs. Certain number of C3 positive RBCs were identified from immediately after the first initiation dose of eculizumab, and the proportion of C3 positive RBCs continuously increased with 14 weeks time course in two patients (UPN6 and 7) who could be monitored from before treatment. Then, the proportion of C3 positive RBCs was monitored at the interval of 15 months during treatment, and the proportion of C3 positive RBCs increased in all patients (Figure 1). At this moment, no one had significant clinical symptoms of extravascular hemolysis, and only UPN3 and 4 showed weak positivity in conventional direct anti-globulin test (DAT) at some points. However, DAT using monospecific anti-C3b plus anti-C3d antibody or anti-C3d antibody alone became positive in five out of six cases except for UPN2.Since CR1 has a crucial role in dissociation of C3/C5 convertases, especially under the conditions of CD55 deficiency, such as PNH, we analyzed the expression levels of CR1 on RBCs. The expression levels of CR1 on RBCs negatively well correlated with the percentage of C3 positive RBCs (Correlation=-0.979) (Figure 2). Since allelic variant of CR1 was known, we screened six patients and no homozygous variant known to express low levels of CR1 was identified. Only heterozygous variant was identified in UPN5 who express slightly low levels of CR1 compared to control (0.47). Then, the kinetics of CR1 and C3 during RBC maturation were analyzed in fractions of reticulocytes and mature RBCs. The proportion of C3 positive RBCs tended to increase, whereas the expression of CR1 tended to decrease during RBC maturation in four patients (UPN3,4,5 and 7).Thus, we confirmed that patients with PNH started to have C3 positive RBCs mediated by the treatment of eculizumab without exception, and the proportion of C3 positive RBCs increased during treatment. Most patients showed positive DAT using monospecific anti-C3b/anti-C3d antibody, even if there is no significant clinical symptoms of extravascular hemolysis. We also identified that the patients expressing high levels of CR1 tended to have low proportion of C3 positive RBCs, and the expression of CR1 tended to decrease with increasing the proportion of C3 positive RBCs during RBC maturation. We have successfully established several methods to monitor the kinetics of CR1 and C3, although current data are still not conclusive because analyzed patients had little symptoms. Therefore, we have conducted the research project to recruit the patients having significant clinical symptoms of extravascular hemolysis. [Display omitted] [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

The Benefit of RED CELL Antigen Testing in A Transfusion Service of A Large Cancer Center

AbstractAbstract 4374 Introduction:DNA-based tests are increasingly being used to predict blood group phenotypes in patients who have been recently transfused to aid in alloantibody identification, to distinguish an alloantibody from an autoantibody, in patients who have received hematopoietic stem cell transplants, when RBCS are coated with immunoglobulin (+DAT) and to detect weakly expressed antigens when the patient is unlikely to make antibodies to antigen- positive RBC's transfused. The molecular bases associated with most antigens have been determined and PCR-assays available for testing RBC antigens are a powerful adjunct to the conventional hemagglutination, the gold standard technique to type RBCs for the presence or absence of blood group antigens. Purpose:This retrospective review of Red Blood cell (RBC) antigen testing data was conducted on all patients typed between January 2010 and December 2011 at MD Anderson Cancer Center. The purpose was to review the concordance between the antibody (ies) identified by serologic testing and the antigen negativity from phenotype predicted from DNA analysis for selecting antigen negative RBCs for transfusion. In addition we also wanted to review whether the extended phenotype red cell units transfused to patients with unidentified alloantibody (ies)/RACT and autoantibodies formed additional red cell alloantibody (ies) after transfusion. Methods:The technology of BioArray Solutions (Bioarray Solutions, Immuncor, Norcross, GA, USA) and the Human Erythrocyte Antigen (HEA) v1.2 BeadChip was used to assess the genotype and predicted phenotype of patients. We performed RBC antigen testing on all of our recently transfused patients with alloantibody (ies), patients whose red cell antibody panels showed reaction with all red cells tested (RACT) or unidentified antibodies, patients with positive direct antiglobulin test (DAT) and whose elution studies showing RACT or unidentified antibody (ies) and in patients with autoimmune hemolytic anemia. Results:Atotal of 912 BioArray tests were performed on 912 patients [444 (49%) males:468 (51%) females; median age 60 years (range 1–92)]. Antibody screen was positive in 424 (46%) and negative in 488 (54%) patients. A DAT was performed in 126 patients with a positive antibody screen to establish immune from non-immune hemolytic anemia. The results are listed in Tables 1,2 and 3. Conclusion:We found 100% concordance between the predicted antigen negativity phenotype and the patient's RBC alloantibody (ies) identified by serologic testing. The RBC antigen typing has allowed us to transfuse patients with unidentified antibodies and RACT with extended phenotype matched red cell units preventing the development of additional red cell alloantibody (ies) as well as allowed us to transfuse antigen-negative units preventing patient/blood donor incompatibility issues.Table 1Results of Red cell Antibody Screen, DAT and Elution testingBioArray Tests (n)912Antibody Screen (n): Positive/Negative424 (46%)/488 (54%)Positive Antibody screen, Positive DAT (n)108 (25%)Positive Antibody screen, Negative DAT (n)18 (4%)Positive Antibody screen, DAT not performed (n)298 (70%)Positive DAT, Positive Elution (n)96IgG and C3d40IgG64C3d4Positive Antibody Screen (n)424Reactive with all cells tested (RACT)42 (9.9%)Unidentified Antibody(ies)80 (19%)Alloantibody and Unidentified Antibody(ies)35 (8%)Alloantibody and RACT9 (2%)Specific Alloantibody (ies) 1 or more256 (60%)Antibody Identification- Not performed2 (0.1%)Table 2Results of Single red cell alloantibodies identifiedSingle Red Cell Alloantibodies (n)209Anti-E69 (33%)Anti-D50 (24.2%)Anti-K44 (21.1%)Anti-Fya12 (5.7%)Anti-C8 (3.8%)Anti-Jka8 (3.8%)Anti-M7 (3.3%)Anti-Lea3 (1.4%)Anti-S3 (1.4%)Anti-c2 (0.9%)Anti-P12 (0.9%)Anti-Jkb1 (0.5%)Table 3Results of 2 or more red cell alloantibodies identifiedAlloantibodies (2 or more((n)47Anti-E Anti-K10 (21.3%)Anti-D Anti-C9 (19.2%)Anti-C Anti-D Anti-E5 (10.7%)Anti-D Anti-E3 (6.4%)Anti-E Anti-Fya3 (6.4%)Anti-c Anti-E2 (4.3%)Anti-E Anti-Jka2 (4.3%)Anti-E Anti-Jkb2 (4.3%)Anti-C Anti-E1 (2.1%)Anti-C Anti-K1 (2.1%)Anti-D Anti-Jka1 (2.1%)Anti-D Anti-K1 (2.1%)Anti-E Anti-Lua1 (2.1%)Anti-Fya Anti-K1 (2.1%)Anti-K Anti-Fya1 (2.1%)Anti-c Anti-E Anti-Fya1 (2.1%)Anti-D Anti-C Anti-Fya1 (2.1%)Anti-D Anti-C Anti-K1 (2.1%)Anti-K Anti-Fya Anti-Lea1 (2.1%) Disclosures:No relevant conflicts of interest to declare.

Use of Emergency-Release, Uncrossmatched O Negative Red Blood Cells (RBCs) in a Tertiary Care Children's Hospital

Abstract 4341 Background:Transfusion services must offer means of issuing blood products quickly for emergent transfusions. At Lucile Packard Children's Hospital (LPCH), off-site refrigerators were installed in the Neonatal Intensive Care Unit (NICU), the LPCH operating room (OR) and the Cardiovascular Intensive Care Unit (CVICU) inventoried with uncrossmatched O negative RBCs for immediate emergency use. Uncrossmatched O negative RBCs are also provided to children undergoing cardiac catheterization at the discretion of the Pediatric Cardiologist, since these patients commonly do not have type and screen samples drawn until large vessel venous cannulation via insertion of the catheter. Uncrossmatched blood products are also provided for children per our massive transfusion protocol (MTP). The purpose of this study was to assess the utilization of these uncrossmatched blood products in children and its impact on transfusion service (TS) inventory of O negative RBCs. Methods:Orders received for emergency-release uncrossmatched RBCs for patients ages 0 days to 18 years including MTPs from January 1 2011 to March 31 2011 were evaluated retrospectively. Variables collected include: patient demographic information and diagnosis; blood products ordered, released and transfused; location of the patient and location from where blood was dispensed (off-site refrigerator versus [vs] TS). Results:Median patient age was 3.46 years (range 0 days to 15.62 years), and 82% of the patients had congenital heart disease. Sixty four RBCs were issued to 33 patients during the 3-month study period. Of those, 32 RBCs were transfused, 8 RBCs were wasted because temperature parameters were exceeded before return to the TS, and 24 RBCs (38%) were not transfused and returned to TS inventory. Nineteen of the 32 RBCs were transfused, representing 2% of the total 964 O negative RBC units transfused at our institution for that time period. Nineteen (58%) units were for children in the cardiac catheterization suite. Seven patients were in the CVICU, five children were in the NICU, and two were in the Pediatric Intensive Care Unit. Two units of O negative RBCs were dispensed from the emergency off-site refrigerator in the CVICU. Discussion:The majority of children (79%) who received emergency-release uncrossmatched O negative RBCs at LPCH were those with congenital heart disease undergoing cardiac catheterization or being cared for post-operatively in the CVICU. There were 2 instances of children requiring RBCs from off-site refrigerators for an emergent transfusion. Emergency-release, uncrossmatched O negative RBCs at LPCH either from the TS or from three off-site refrigerators caused no undue strain on our supply and inventory of donor O negative RBCs. Disclosures:No relevant conflicts of interest to declare.