Search Results (14)

Background: Maternal anti-D antibody titers are routinely used for risk stratification in RhD alloimmunization before the development of fetal anemia. However, their association with disease severity and perinatal outcomes among pregnancies that have already progressed to severe fetal anemia requiring intrauterine transfusion (IUT) remains unclear. This study aimed to investigate the association between maternal anti-D antibody titers, disease severity, and perinatal outcomes in pregnancies complicated by severe RhD alloimmunization requiring IUT. Methods: This retrospective cohort study included 38 RhD-alloimmunized pregnancies complicated by severe fetal anemia and managed with IUT at a tertiary referral center between January 2017 and December 2022. Maternal characteristics, anti-D antibody titers, presence of hydrops fetalis, IUT characteristics, delivery data, neonatal outcomes, and mortality were evaluated. Maternal anti-D antibody titers were analyzed in relation to disease severity and perinatal outcomes. Results: Hydrops fetalis was present in 24 fetuses (63.2%). The mean maternal age was 30.3 ± 4.8 years, and the mean gestational age at diagnosis was 23.5 ± 5.8 weeks. Maternal anti-D antibody titers were significantly higher in pregnancies complicated by hydrops fetalis than in non-hydropic pregnancies (p = 0.014). No significant associations were observed between maternal anti-D antibody titers and intrauterine fetal demise, neonatal mortality, neonatal intensive care unit admission, Apgar scores, or the number of IUT procedures. Conclusions: Among pregnancies with severe RhD alloimmunization requiring intrauterine transfusion, higher maternal anti-D antibody titers were associated with hydrops fetalis, suggesting an association with disease severity. However, no statistically significant associations were observed between maternal anti-D antibody titers and other evaluated perinatal outcomes in this high-risk cohort. These findings indicate that, once severe fetal anemia requiring IUT has developed, maternal anti-D antibody titers should be interpreted alongside fetal Doppler surveillance and comprehensive clinical assessment rather than as independent predictors of perinatal prognosis. Full article

Background/Objectives: Blood group antigen frequencies vary across ethnic populations and are critical for safe transfusion practice, inventory management, and alloimmunization prevention. This study aimed to determine ABO blood group, extended Rh phenotype (D, C, c, E, e), and K antigen frequencies among blood donors at the Riyadh Regional Blood Bank, and to examine their associations with donor ethnicity. Methods: This retrospective cross-sectional study analyzed 10,463 blood donors (January–December 2021) using the Immucor NEO Iris fully automated immunohematology analyzer. Donors were classified into five ethnic groups. Chi-square tests assessed associations (p < 0.05), the primary scientific contribution is the descriptive frequency data, with hypothesis testing presented as secondary and exploratory. Results: Most donors were male (95.2%). Blood group O+ was most prevalent (31.6%); AB− was rarest (0.9%). Rh D-positivity was 84.7%, lowest among Saudis (81.1%). The most frequent Rh phenotypes were CcDee (24.2%), ccDee (19.9%), and CCDee (17.7%). K antigen positivity was 13.7%. Significant associations were found between D antigen and ethnicity (p < 0.001), Rh phenotype and ethnicity (p = 0.003), and ABO and ethnicity (p < 0.001). A hypothesis-generating association between Rh phenotype and K antigen (p = 0.019) did not meet the Bonferroni-corrected threshold and is considered exploratory. Conclusions: This study provides, to our knowledge, one of the largest ethnically stratified blood group datasets from Riyadh to date. The high D-negativity among Saudi donors (18.9%) has direct implications for extended phenotyping protocols and rare donor registry development. The association between Rh phenotype and K antigen requires molecular confirmation before any biological or clinical conclusions can be drawn. Full article

The designation of O RhD-negative blood as a “universal donor” misrepresents the complexity of red blood cell (RBC) compatibility. With 47 recognized blood group systems encompassing 366 antigens, non-ABO antigen exposure drives alloimmunization in 20–50% of chronically transfused patients. A narrative review of PubMed, Scopus, and EMBASE was conducted for studies published between 2016 and 2025, with selective inclusion of foundational pre-2016 works. Enzymatic approaches using Flavonifractor plautii CAZymes and Akkermansia muciniphila exoglycosidase cocktails enable near-complete ABO antigen removal, though group A conversion remains incomplete. CRISPR-Cas9 multiplex editing of immortalized erythroblasts has achieved simultaneous deletion of ABO, Rh, Kell, Duffy, and MNS antigens. Induced pluripotent stem cell platforms enable scalable manufacture; however, enucleation efficiency (40–70%), yield (4.6 × 10³ RBCs/iPSC), and fetal hemoglobin prevalence remain translational barriers. Convergence of enzymatic and gene-editing technologies on GMP-compatible iPSC platforms represents the most credible pathway to truly universal RBCs, although current evidence remains largely confined to immortalized cell lines and early-stage iPSC proof-of-concept studies rather than clinically validated products. Regulatory frameworks, scalability, and rigorous off-target profiling define the key challenges ahead. Full article

Background/Objectives: Thalassemia and sickle cell anemia (SCA) patients require regular blood transfusions, a necessity that increases the risk of alloimmunization and complicates subsequent transfusion management. Methods: This retrospective cohort study, conducted at King Saud Medical City (KSMC) and King Fahad Medical City (KFMC) between 2018 and 2022, evaluated the frequency and risk factors of alloimmunization among 144 transfusion-dependent patients in Riyadh, Saudi Arabia. Results: By reviewing clinical and transfusion records alongside antibody screening results, the study found an overall alloimmunization prevalence of 20.1%. Notably, females exhibited a significantly higher rate (13.2%) compared to males (6.8%; p = 0.003), and younger patients (<20 years) showed a higher prevalence than older cohorts (p = 0.004). Analysis of ABO blood groups revealed that group A patients had a significantly lower alloimmunization rate (7.5%) compared to non-A patients (23.1%; p = 0.018), a finding that raises hypotheses about differential immune responsiveness but requires confirmation in larger studies. Group B showed the highest rate (35.3%), though this did not reach statistical significance after correction for multiple comparisons. RhD status was not significantly associated with alloimmunization. The most frequent alloantibodies identified were anti-E (31.3%), anti-K (12.5%), anti-D (10.4%), and anti-C (10.4%). Logistic regression further identified gender as a significant predictor (OR = 0.270; 95% CI: 0.113–0.646). Conclusions: Given that alloimmunization rates in Riyadh are moderately high—particularly among females and specific blood groups—and that the antibody profile (anti-E, anti-K, anti-C, anti-D) mirrors patterns seen in populations with recipient–donor ethnic mismatches, implementing extended blood group phenotyping for at least Rh (C, c, E, e) and Kell antigens prior to the first transfusion, and incorporating these findings into donor selection protocols, is critical to mitigating these risks. Full article

Background: Feto-maternal hemorrhages (FMHs) due to placenta disruption and bleeding from fetal maternal circulation can lead to life-threatening fetal anemia. These hemorrhages are more often of small volume and remain unreported. Sensitization to fetal red blood cell (RBC) antigens can occur during pregnancy, at delivery, or after invasive procedures. The sensitized mother produces IgG antibodies (abs) that cross the placenta and cause the hemolysis of fetal RBCs, release of hemoglobin, and increased levels of unconjugated bilirubin in the fetus or neonate. The result is hemolytic disease of the fetus and newborn (HDFN). Methods: In this study, we aim to provide a structured overview of RBC alloimmunization in pregnancy. A literature search was conducted using PubMed. English articles published from January 2010 to October 2025 were selected by the authors. The contributing manuscripts focused on managing RBC alloimmunization in pregnancy, FMH screening and quantification, antenatal and postnatal testing, Rh immune globulin (Rh Ig or Anti-D) prophylaxis, and national registry data. Results: Frequencies of RBC abs vary among American, Caucasian, and Asian populations because of genetic diversity, different antibody detection and antibody identification methods, and FMH tests. More specifically, the erythrocyte rosette is a simple screening test for FMH. A positive rosette must be quantified by the Kleihauer–Betke (KB) or flow cytometry (FC). The KB results may be overestimated or underestimated. The advantages of FC include high accuracy, specificity, and repeatability. Ultimately, anti-D prophylaxis protocol varies from country to country. Conclusion: Maternal alloimmunization is an uncommon and highly variable event. Although introducing anti-D prophylaxis has decreased the Rh immunization rate, it is still an unmet medical need. In brief, mitigation strategies for RBC alloimmunization risk include accurate maternal and neonatal testing at different time points, adequate Rh immune globulin prophylaxis in D-negative pregnant women, preventing sensitizing events, adopting a conservative transfusion policy, and upfront ABO and Rh (C/c, E/e) and Kell matching in females under 50 years of age. Full article

Hemolytic disease of the fetus and newborn (HDFN) is a severe complication of pregnancy caused by maternal alloimmunization to fetal red blood cells, leading to significant perinatal morbidity and mortality. The prognosis is particularly poor in cases complicated by fetal hydrops. Prophylactic administration of anti-D immunoglobulin—during pregnancy, postpartum, and after events causing fetomaternal hemorrhage—has substantially reduced the incidence and severity of Rh-related HDFN. Nevertheless, the condition can still occur, either due to omitted prophylaxis or undetected fetomaternal hemorrhage. Definitive management often requires invasive interventions, including cordocentesis and intrauterine transfusions (IUTs), sometimes repeated multiple times, while the optimal timing of delivery remains uncertain, necessitating a careful balance between prematurity and ongoing fetal risk. We report the case of a 35-year-old multipara whose two most recent pregnancies were complicated by HDFN. The first affected pregnancy had a mild course, whereas the second was severe, necessitating multiple intrauterine transfusions (IUTs) throughout gestation. Despite an extremely low initial fetal hematocrit (4.5%), severe hydrops, and the requirement of six intrauterine transfusions (IUTs) during the pregnancy, the infant was delivered at 36 weeks’ gestation with a favorable postnatal outcome. This case report provides a comprehensive overview of intrauterine transfusion methodology, post-transfusion pregnancy monitoring, timing of successive IUTs, and optimal delivery planning in pregnancies complicated by HDFN. Full article

Introduction: For pregnant women with a history of fetal and neonatal alloimmune thrombocytopenia (FNAIT) or hemolytic disease of the fetus and newborn (HDFN), prenatal intervention in subsequent pregnancies may be necessary to prevent complications for the fetus. A non-invasive prenatal diagnostic procedure (NIPD) is recommended for fetal blood group genotyping. RT-PCR is used for fetal RHD determination as a reliable screening method with high sensitivity and specificity. For other antigens with variants involving single-base substitutions, droplet digital PCR (ddPCR) and next-generation sequencing (NGS) are recommended to reduce the risk of false-negative results. Only NGS offers the possibility of determining the cell-free fetal DNA (cffDNA) fraction in maternal plasma by sequencing additional gene fragments in parallel, but no standard exists for assay validation. Material and Methods: A custom-made primer panel was designed to target the common platelet and red cell antigens involved in fetal red cell and platelet incompatibilities, as well as additional anonymous single-nucleotide polymorphism (SNP) targets for use as an internal control. Amplicon-based NGS was carried out using semiconductor sequencing. For HPA-1a (HPA*1A, ITGB3) and K (KEL*01.01, KEL) assay validation, the limit of detection (LOD) and limit of quantification (LOQ) were estimated, as were false-positive antithetic alleles, linearity, and inter-assay variation, using cell-free DNA (cfDNA) extracted from the blood samples of healthy blood donors. An additional analysis was performed using 23 diagnostic samples from 21 pregnant women. Results: Regression analysis of dilution series using HPA-1a- and K-positive cell-free plasma samples in antigen-negative donor plasma showed that recovery is definitely feasible up to an HPA*1A and KEL*01.01 allele frequency of 1%. Base calls of false-positive antithetic alleles were detected with a maximum of 0.25% using 21 healthy blood donors. The LOD was estimated to be 0.2057% (mean + 3 SD) for HPA*1A with a LOQ of 0.6298% (mean + 10 SD). For KEL*01.01, the LOD was 0.1706% (mean + 3 SD) and the LOQ was 0.5314% (mean + 10 SD). The analysis of 15 of 21 cases with diagnostic samples from pregnant women with neonatal blood available for confirmatory testing resulted in 100% concordant results. The fetal fraction of these samples was calculated with a median of 11.03% (95% CI: 8.89, 13.20). Conclusions: NGS for non-invasive fetal blood group genotyping is an accurate and reliable method. In-house validation of the used assays can be performed using healthy donors to determine the LOD, LOQ and sensitivity. The threshold for paternally inherited fetal HPA*1A and KEL*01.01 alleles could be set at 1% (i.e., 2% fetal fraction) to obtain reliable test results. Internal controls for assessing the fetal fraction are essential to avoid false-negative test results. Full article

Background: Today, in Western countries, patients with allo-antibodies to high-frequency antigens or with complex antibody mixtures represent one of the most significant challenges in transfusion medicine. Another important aspect is the prevention of allo-immunization of patients who lack high-frequency antigens. In these conditions, the availability of a bank of a rare red blood cell group, supported by a database of donors subjected to extensive erythrocyte typing (preferably using erythrogenomic study), can constitute a resource of great value. Materials and Methods: Repeat Caucasian blood donors of group A or O, with selected Rh phenotypes (CCDee, ccDEE, ccdee, ccDee), aged under 52 years, were considered for typing. Moreover, we selected all non-Caucasian repeat blood donors for typing. For extended phenotyping and genotyping we adopted commercial methods supplied by Grfols and Werfen, respectively. For cryopreservation, we selected a high glycerol method in −80 °C electric freezer; blood unit processing was performed using a Haemonetics ACP 215 automated cell processor with close circuit devices. Results: We considered the five patients as follows: PA was massively transfused for a road trauma, developed multiple allo-antibodies (anti-D, anti-k), and required compatible blood units for an elective cardiac surgery; PB was a pregnant woman with anti-Coa (a high frequency antigen) monitored during pregnancy and in which it was necessary to proceed with the transfusion of the newborn; PC was a poly-transfused patient with myelo dysplastic syndrome who developed multiple allo-antibodies (anti-k, anti-CW, anti-Lea) and required continuous supportive therapy, including the procurement of compatible units and the implementation of therapeutic actions in an attempt to reduce the transfusion requirement using luspatercept; PD was a patient with sickle cell disease. They had a Fy (null) genotype, making it very difficult to find compatible units; and PE was interesting for the complexity of the immunohematological and erythrogenomic study performed to characterize a recipient with a rare phenotype and thus allow the transfusion of compatible units, preventing allo-immunization. Discussion: In this report, we have maintained a narrative approach. Starting with five patients representing as many clinical situations as possible, we have illustrated the approach followed for the immune-hematological study and the choices made to try to guarantee effective and safe transfusion therapy. Full article

Background/Objectives: Red blood cell (RBC) alloimmunization is a significant challenge in transfusion medicine, particularly among transfusion-dependent patients, such as those with thalassemia. It arises from the production of antibodies against non-self RBC antigens and can lead to complications like hemolytic transfusion reactions. This study aimed to evaluate the prevalence, specificity, and clinical implications of RBC alloimmunization at the University Clinical Center of Serbia (UCCS), emphasizing transfusion-dependent populations. Methods: This retrospective study analyzed 27,530 transfusion records at UCCS between January 2023 and January 2024. Pre-transfusion testing included ABO and RhD typing, irregular antibody screening, and crossmatching. Data from 630 patients with positive antibody screening were reviewed. Alloantibody specificity was determined using indirect antiglobulin tests and advanced phenotyping methods. Results: Among 27,530 patients, 630 (2.29%) tested positive for irregular antibodies, predominantly males (57.14%) with a mean age of 49.6 years. Alloantibodies were detected in 70.47% of cases, most commonly targeting Rh (53.35%) and Kell (17.15%) systems. Anti-E (27.93%) and anti-D (18.02%) were the most frequent antibodies. Multiple alloantibodies were identified in 18.41% of patients, posing challenges for blood compatibility. In a total of 495 patients with thalassemia, antibodies were found in 9.69%. Alloimmunization was significantly associated with higher numbers of transfusions and pregnancies (p < 0.05). Conclusions: Our findings indicate that alloimmunization is predominantly associated with Rh and Kell antigens, suggesting that implementing targeted antigen matching may reduce the frequency of alloimmunization. While our study does not directly assess the impact of genotypic matching, the prior literature supports its role in enhancing transfusion safety, particularly for high-risk populations like thalassemia patients. Full article

Background and Objectives: The Rh blood group system is highly polymorphic, and accurate classification of Rh(D) variants is critical in transfusion medicine to prevent alloimmunization and optimize blood utilization. Despite the advances in conventional serologic testing, weak and partial Rh(D) phenotypes still remain challenges in Transfusion Medicine practice. The objective is to implement and assess the impact of RHD genotyping in classifying Rh(D) antigen status. Materials and Methods: We conducted a retrospective study at the University of South Alabama Medical Center and Children and Women’s Hospital between 1 January 2023 and 31 December 2024 to assess the impact of RHD genotyping in cases with discrepant Rh(D) typing, Rh(D)-positive patients with anti-Rh(D) antibodies, and neonates with positive weak Rh(D) tests. ABO and Rh(D) antigen typing was performed on 12,994 patients, including 3767 newly tested individuals. Weak Rh(D) testing was performed on newly tested individuals using automated microplate direct agglutination, followed by molecular genotyping. Results: Among the 25 patients with weak or discrepant Rh(D) phenotypes, weak Rh(D) variants were observed in 52% of cases, with Weak Type 2 being the most common, particularly in pediatric (age < 18 years old) patients. Partial Rh(D) phenotypes were identified in 40% of cases, predominantly among Black individuals. Three patients were reclassified as Rh(D)-positive based on genotyping and received 615 Rh(D)-positive RBC units without evidence of alloimmunization, while four patients were confirmed at risk of alloimmunization and remained classified as Rh(D)-negative. Fisher’s exact test demonstrated a significant association between ethnicity and Rh(D) classification (p < 0.01), and the McNemar exact test confirmed a significant reclassification of cases from Rh(D)-negative to Rh(D)-positive (p < 0.01). Conclusions: RHD genotyping enhances the accuracy of Rh(D) antigen classification, mitigating alloimmunization risks and the unnecessary use of Rh Immunoglobulin and optimizing blood product utilization. The reclassification of patients to Rh(D)-positive alleviates pressure on Rh(D)-negative blood supplies, particularly during critical shortages. These findings underscore the necessity of integrating molecular RHD testing into routine transfusion medicine practices to improve patient safety and resource management. Full article

Background: Sickle cell disease (SCD) affects approximately 100,000 people in the United States and millions worldwide, with the highest prevalence of 70% of SCD being found in individuals of African ethnicity. Delayed hemolytic, alloimmunization, and anamnestic transfusion reactions in multiple transfusion patients need to be investigated and managed to avoid a worsening of the patient’s clinical status. Objective: This paper aims to investigate delayed transfusion reactions in SCD patients who were polytransfused in the Brazilian Amazon. Material and Methods: The clinical and laboratory indicators of SCD patients with more than four transfusions were investigated. The patients were treated at the Fundação Hospitalar de Hematologia e Hemoterapia do Estado do Amazonas, Brazil. Results: A total of 44 polytransfused patients with SCD were followed. Regarding Rh phenotype, it was possible to observe a frequency of 26.6% (12) patients with the RZRZ (DCE/DCE) phenotype, in addition to 4.5% (two) patients with RH and RHCE variants. It was also possible to observe 20.5% (nine) patients with an alloimmunization reaction, who presented the following alloantibodies: anti-RhD, anti-E, anti-K, anti-Jk^b, anti-N, anti-S, and anti-Di^a, two of which are unidentified. Of these, four (44.4%) patients also presented autoantibodies, anti-e, and three unidentified antibodies, and four (44.4%) patients presented an anamnestic reaction, with anti-RhD, K, and Jkb antibodies. Of the 44 patients monitored, 54.4% (24) had clinical and laboratory indicators of a delayed hemolytic reaction. Conclusion: Delayed transfusion reactions, often neglected, occur frequently. Therefore, transfusions need to be monitored for at least 28 days, with medical investigation of clinical and laboratory indicators to make greater use of this therapeutic resource. Full article

Hemolytic disease of the fetus and newborn (HDFN), as well as fetal and neonatal alloimmune thrombocytopenia (FNAIT), represent two important disease entities that are caused by maternal IgG antibodies directed against nonmaternally inherited antigens on the fetal blood cells. These antibodies are most frequently directed against the RhD antigen on red blood cells (RBCs) or the human platelet antigen 1a (HPA-1a) on platelets. For optimal management of pregnancies where HDFN or FNAIT is suspected, it is essential to determine the RhD or the HPA-1a type of the fetus. Noninvasive fetal RhD typing is also relevant for identifying which RhD-negative pregnant women should receive antenatal RhD prophylaxis. In this review, we will give an overview of the clinical indications and technical challenges related to the noninvasive analysis of fetal RBCs or platelet types. In addition, we will discuss the ethical implications associated with the routine administration of antenatal RhD to all pregnant RhD-negative women and likewise the ethical challenges related to making clinical decisions concerning the mother that have been based on samples collected from the (presumptive) father, which is a common practice when determining the risk of FNAIT. Full article

Noninvasive fetal RHD genotyping is an important tool for predicting RhD incompatibility between a pregnant woman and a fetus. This study aimed to assess a methodological approach other than the commonly used one for noninvasive fetal RHD genotyping on a representative set of RhD-negative pregnant women. The methodology must be accurate, reliable, and broadly available for implementation into routine clinical practice. A total of 337 RhD-negative pregnant women from the Czech Republic region were tested in this study. The fetal RHD genotype was assessed using two methods: real-time PCR and endpoint quantitative fluorescent (QF) PCR. We used exon-7-specific primers from the RHD gene, along with internal controls. Plasma samples were analyzed and measured in four/two parallel reactions to determine the accuracy of the RHD genotyping. The RHD genotype was verified using DNA analysis from a newborn buccal swab. Both methods showed an excellent ability to predict the RHD genotype. Real-time PCR achieved its greatest accuracy of 98.6% (97.1% sensitivity and 100% specificity (95% CI)) if all four PCRs were positive/negative. The QF PCR method also achieved its greatest accuracy of 99.4% (100% sensitivity and 98.6% specificity (95% CI)) if all the measurements were positive/negative. Both real-time PCR and QF PCR were reliable methods for precisely assessing the fetal RHD allele from the plasma of RhD-negative pregnant women. Full article

SHOT (Serious Hazards of Transfusion scheme) is the UK’s National confidential haemovigilance system, and was set up in 1996. It is an independent, confidential, professionally led haemovigilance scheme. Initially the reporting was voluntary but now required by several professional bodies. SHOT publishes annual reports with recommendations and circulates to all relevant organizations including the 4 UK Blood services, Departments of Health in England, Wales, Scotland and Northern Ireland, all relevant professional bodies and reporting hospitals. Over the 17 years of reporting, the evidence gathered has prompted changes in transfusion practice from the selection and management of donors to changes in hospital practice, better education and training. Acute transfusion reactions and transfusion-associated circulatory overload carry the highest risk for morbidity and death. Greatest risk to patients remain errors in the process at the point of blood sampling, in the laboratory and at bedside administration. SHOT’s objectives are to use findings to improve standards of hospital transfusion practice, to educate users on transfusion hazards and prevention, to aid production of clinical guidelines in blood transfusion and to inform national policy on transfusion safety. MHRA is the UK competent authority to which serious adverse reactions and events have to be reported annually. Overall the most common adverse incidents are caused by errors, resulting in the transfusion of an incorrect component or one that does not meet the specific requirements of the patient (e.g. not irradiated or not appropriately antigen matched). TACO (transfusion associated circulatory overload) accounts for most deaths and major morbidity reported to SHOT but is overall underreported. Transfusions are not always given appropriately. This may be due to wrong haemoglobin results, failure to assess patients appropriately, or avoidable use of emergency O RhD negative units because of poor communication or planning. Review of cases of haemolytic transfusion reactions (HTR) shows that they are observed mainly in Sickle Cell Disease patients. HTR are associated with major morbidity (10/16 cases in sickle cell patients over 3 years) and death (a child in 2010). SCD patients are at particular risk of alloimmunization and this can be reduced by red cell phenotyping prior to the first transfusion followed by routine matching for at least the Rh and Kell groups. SHOT output data led over the time to the development of strategies to improve transfusion safety such as the implementation of guidelines for improving practice, implementation of the National Comparative Audit of Blood Transfusion programme, the publication of the Better blood transfusion initiatives and the establishment of The UK transfusion laboratory collaborative. Full article