BACKGROUND: Immunohematology skill education is an important part of the transfusion medicine professional training. We tried to solve the difficulty of obtaining suitable and sufficient positive samples in the immunohematology education.
METHODS: Different identification panels and panel cells were created by RhD-positive red blood cells (RBCs) and RhD-negative RBCs, according to the underlying antibodies. Diluted anti-D reagent was used as simulated plasma for identification.
RESULTS: The antibody identification of single antibody with dose-effect and two antibodies present at the same time were successfully simulated.
CONCLUSIONS: It is a practical and cheap method for antibody identification training to use RhD blood group, especially when positive samples are short.

The level of anti-D antibodies in human immunoglobulin products for intravenous administration (IVIG) is controlled by the direct haemagglutination method prescribed by the European Pharmacopoeia (Ph. Eur.) that requires 2 control reference reagents. The World Health Organization (WHO) positive control International Reference Reagent (IRR; 02/228) with a nominal titre of 8 defines the highest acceptable titre, while the negative control preparation (02/226) has a nominal titre of <2. Working reference preparations (04/132 and 04/140) were subsequently established as Biological Reference Preparations (BRPs) for the Ph. Eur., and for distribution by the United States Food and Drug Administration (US FDA) and the National Institute for Biological Standards and Control (NIBSC). Due to diminishing stocks of these working reference preparations across the 3 institutions, a joint international study was organised to establish harmonised replacement batches. Sixteen laboratories contributed data to the study to evaluate positive and negative candidate replacement batches (13/148 and 12/300, respectively) against the WHO positive and negative control IRRs and the current working reference preparations (BRPs). The results show that the candidate reference preparations (13/148 and 12/300) are indistinguishable from the corresponding IRRs and current BRPs. The candidate preparations 13/148 and 12/300 were adopted by the Ph. Eur. Commission as Immunoglobulin (anti-D antibodies test) BRP batch 2 and Immunoglobulin (anti-D antibodies test negative control) BRP batch 2 with nominal haemagglutination titres of 8 and <2, respectively. The same materials were also adopted as NIBSC and US FDA reference preparations, thus ensuring full harmonisation.

The high number of D variants can lead to the unnecessary use of Rh immune globulin, overuse of D- RBC units, and anti-D allommunization. D variant prevalence varies among ethnic groups, and knowledge of the main variants present in a specific population, their behavior in serologic tests, and their impact on clinical practice is crucial to define the best serologic tests for routine use. The present study aimed to explore the serologic profile of D variants and to determine which variants are most associated with false-negative D typing results and alloimmunization. Donor samples were selected in two study periods. During the first period, D typing was performed on a semi-automated instrument in microplates, and weak D tests were conducted in tube or gel tests. In the second period, D typing was carried out using an automated instrument with microplates, and weak D tests were performed in solid phase. Samples from patients typed as D+ with anti-D were also selected. All samples were characterized by molecular testing. A total of 37 RHD variants were identified. Discrepancies and atypical reactivity without anti-D formation were observed in 83.4 percent of the samples, discrepant D typing results between donations were seen in 12.3 percent, and D+ patients with anti-D comprised 4.3 percent. DAR1.2 was the most prevalent variant. Weak D type 38 was responsible for 75 percent of discrepant samples, followed by weak D type 11, predominantly detected by solid phase. Among the D variants related to alloimmunization, DIVa was the most prevalent, which was not recognized by serologic testing; the same was true for DIIIc. The results highlight the importance of selecting tests for donor screening capable of detecting weak D types 38 and 11, especially in populations where these variants are more prevalent. In pre-transfusion testing, it is crucial that D typing reagents demonstrate weak reactivity with DAR variants; having a serologic strategy to recognize DIVa and DIIIc is also valuable.

Background: There is insufficient evidence to assess the risk of the production of clinically important alloimmune irregular red blood cell (RBC) antibodies in first-time pregnant women. Methods: Using the microcolumn gel antiglobulin method, 18,010 Chinese women with a history of pregnancy and pregnant women were screened for irregular RBC antibodies, and for those with positive test results, antibody specificity was determined. The detection rate and specificity of irregular RBC antibodies in women with a history of multiple pregnancies (two or more) and first-time pregnant women were determined. Results: In addition to 25 patients who passively acquired anti-D antibodies via an intravenous anti-D immunoglobulin injection, irregular RBC antibodies were detected in 121 (0.67%) of the 18,010 women. Irregular RBC antibodies were detected in 93 (0.71%) of the 13,027 women with a history of multiple pregnancies, and antibody specificity was distributed mainly in the Rh, MNSs, Lewis, and Kidd blood group systems; irregular RBC antibodies were detected in 28 (0.56%) of the 4983 first-time pregnant women, and the antibody specificity was distributed mainly in the MNSs, Rh, and Lewis blood group systems. The difference in the percentage of patients with irregular RBC antibodies between the two groups was insignificant (χ 2 = 1.248, P > 0.05). Of the 121 women with irregular RBC antibodies, nine had anti-Mur antibodies, and one had anti-Dia antibodies; these antibodies are clinically important but easily missed because the antigenic profile of the reagent RBCs that are commonly used in antibody screens does not include the antigens that are recognized by these antibodies. Conclusion: Irregular RBC antibody detection is clinically important for both pregnant women with a history of multiple pregnancies and first-time pregnant women. Mur and Dia should be included in the antigenic profile of reagent RBCs that are used for performing antibody screens in the Chinese population.

OBJECTIVE: Despite advances in the prevention of rhesus (Rh)(D) alloimmunization, alloantibodies to Rh(D) and non-Rh(D) red blood cell antigens continue to be detected in ∼4% of US pregnancies and can result in hemolytic disease of the fetus and newborn (HDFN). Recent reports on HDFN lack granularity and are unable to provide antibody-specific outcomes. The objective of this study was to calculate the frequency of alloimmunization in our large hospital system and summarize the outcomes based on antibody specificity, titer, and other clinical factors.
METHODS: We identified all births in a 6-year period after a positive red blood cell antibody screen result during pregnancy and summarized their characteristics and outcomes.
RESULTS: A total of 707 neonates were born after a positive maternal antibody screen result (3.0/1000 live births). In 31 (4%), the positive screen result was due to rhesus immune globulin alone. Of the 676 neonates exposed to alloantibodies, the direct antibody test (DAT) result was positive, showing antigen-positivity and evidence of HDFN in 37% of those tested. Neonatal disease was most severe with DAT-positive anti-Rh antibodies (c, C, D, e, E). All neonatal red blood cell transfusions (15) and exchange transfusions (6) were due to anti-Rh alloimmunization. No neonates born to mothers with anti-M, anti-S, anti-Duffy, anti-Kidd A, or anti-Lewis required NICU admission for hyperbilirubinemia or transfusion.
CONCLUSIONS: Alloimmunization to Rh-group antibodies continues to cause a majority of the severe HDFN cases in our hospital system. In neonates born to alloimmunized mothers, a positive DAT result revealing antigen-positivity is the best predictor of anemia and hyperbilirubinemia.

In pregnancy, D- pregnant women may be at risk of becoming immunized against D when carrying a D+ fetus, which may eventually lead to hemolytic disease of the fetus and newborn. Administrating antenatal and postnatal anti-D immunoglobulin prophylaxis decreases the risk of immunization substantially. Noninvasive fetal RHD genotyping, based on testing cell-free DNA extracted from maternal plasma, offers a reliable tool to predict the fetal RhD phenotype during pregnancy. Used as a screening program, antenatal RHD screening can guide the administration of antenatal prophylaxis in non-immunized D- pregnant women so that unnecessary prophylaxis is avoided in those women who carry a D- fetus. In Europe, antenatal RHD screening programs have been running since 2009, demonstrating high test accuracies and program feasibility. In this review, an overview is provided of current state-of-the-art antenatal RHD screening, which includes discussions on the rationale for its implementation, methodology, detection strategies, and test performance. The performance of antenatal RHD screening in a routine setting is characterized by high accuracy, with a high diagnostic sensitivity of ≥99.9 percent. The result of using antenatal RHD screening is that 97-99 percent of the women who carry a D- fetus avoid unnecessary prophylaxis. As such, this activity contributes to avoiding unnecessary treatment and saves valuable anti-D immunoglobulin, which has a shortage worldwide. The main challenges for a reliable noninvasive fetal RHD genotyping assay are low cell-free DNA levels, the genetics of the Rh blood group system, and choosing an appropriate detection strategy for an admixed population. In many parts of the world, however, the main challenge is to improve the basic care for D- pregnant women.

OBJECTIVE: To estimate the cost of Rhesus (Rh) testing and prophylaxis for first-trimester vaginal bleeding in the ambulatory setting.
METHODS: We used time-driven, activity-based costing to analyze tasks associated with Rh testing and prophylaxis of first-trimester vaginal bleeding at one hospital-based outpatient and two independent reproductive health clinics. At each site, we observed 10 patients undergoing Rh-typing and two patients undergoing Rh prophylaxis. We computed the costs of blood Rh-typing by both fingerstick and phlebotomy, cost of locating previous blood type in the electronic health record (available for 69.8% of hospital-based patients), and costs associated with Rh immune globulin prophylaxis. All costs are reported in 2021 US dollars.
RESULTS: The hospital-based clinic reviewed the electronic health record to confirm Rh-status (cost, $26.18 per patient) and performed a phlebotomy, at $47.11 per patient, if none was recorded. The independent clinics typed blood by fingerstick, at a per-patient cost of $4.07. Rh-immune globulin administration costs, including the medication, were similar across facilities, at a mean of $145.66 per patient. Projected yearly costs for testing and prophylaxis were $55,831 for the hospital-based clinic, which was the lowest-volume site, $47,941 for Clinic A, which saw 150 patients/month, and $185,654 for Clinic B, which saw 600 patients/month.
CONCLUSIONS: Rh testing and prophylaxis for first-trimester vaginal bleeding generates considerable costs for outpatient facilities, even for Rh-positive patients with a prior blood type on record.
CONCLUSIONS: Rh testing and prophylaxis for first-trimester bleeding generate considerable costs even for Rh-positive patients and those with a previously known blood type. These findings highlight the need to reconsider this practice, which is no longer supported by evidence and already safely waived in multiple medical settings in the United States and around the world.

BACKGROUND: Anti-D can be formed after D-incompatible platelet transfusions due to contaminating D+ red blood cells. These antibodies are of particular importance in women of childbearing potential, because anti-D is most often involved in severe cases of hemolytic disease of the fetus and newborn. This systematic review determined the frequency of anti-D after D+ platelet transfusions and risk factors for D alloimmunization.
METHODS: Relevant literature was searched using PubMed, Embase and Web of Science until December 2022. Overall anti-D frequency and risk factors were estimated using a random effects meta-analysis.
RESULTS: In 22 studies, a total of 3028 D- patients received a mean of six D+ platelet transfusions. After a mean follow-up of seven months 106 of 2808 eligible patients formed anti-D. The pooled anti-D frequency was 3.3% (95% CI 2.0-5.0%; I2 71%). After including only patients with an undoubtable follow-up of at least 4 weeks, 29 of 1497 patients formed anti-D with a pooled primary anti-D rate of 1.9% (95% CI 0.9-3.2%, I2 44%). Women and patients receiving whole blood derived platelets had two and five times higher anti-D rates compared with men and patients receiving apheresis derived platelets, respectively.
CONCLUSIONS: Anti-D immunization is low after D incompatible platelet transfusions and dependent on recipients\' sex and platelet source. We propose anti-D prophylaxis in girls and women, capable of becoming pregnant in the future, that received D+ platelets, regardless of platelet source, to reduce the risk of anti-D induced hemolytic disease of the fetus and newborn.

BACKGROUND: Low-titer group O whole blood (LTOWB) for treatment of hemorrhagic shock sometimes necessitates transfusion of RhD-positive units due to short supply of RhD-negative LTOWB. Practitioners must choose between using RhD-positive LTOWB when RhD-negative is unavailable against the risk to a female of childbearing potential of becoming RhD-alloimmunized, risking hemolytic disease of the fetus and newborn (HDFN) in future children, or using component therapy with RhD-negative red cells. This survey asked females with a history of red blood cell (RBC) alloimmunization about their risk tolerance of RhD alloimmunization compared to the potential for improved survival following transfusion of RhD-positive blood for an injured RhD negative female child.
METHODS: A survey was administered to RBC alloimmunized mothers. Respondents were eligible if they were living in the United States with at least one red cell antibody known to cause HDFN and if they had at least one RBC alloimmunized pregnancy.
RESULTS: Responses from 107 RBC alloimmmunized females were analyzed. There were 32/107 (30%) with a history of severe HDFN; 12/107 (11%) had a history of fetal or neonatal loss due to HDFN. The median (interquartile range) absolute improvement in survival at which the respondents would accept RhD-positive transfusions for a female child was 4% (1%-14%). This was not different between females with and without a history of severe or fatal HDFN (p = .08 and 0.38, respectively).
CONCLUSIONS: Alloimmunized mothers would accept the risk of D-alloimmunization in a RhD-negative female child for improved survival in cases of life-threatening bleeding.

OBJECTIVE: This guideline provides recommendations for the prevention of Rh D alloimmunization (isoimmunization) in pregnancy, including parental testing, routine postpartum and antepartum prophylaxis, and other clinical indications for prophylaxis. Prevention of red cell alloimmunization in pregnancy with atypical antigens (other than the D antigen), for which immunoprophylaxis is not currently available, is not addressed in this guideline.
METHODS: All Rh D-negative pregnant individuals at risk for Rh D alloimmunization due to potential exposure to a paternally derived fetal Rh D antigen.
RESULTS: Routine postpartum and antepartum Rh D immunoprophylaxis reduces the risk of Rh D alloimmunization at 6 months postpartum and in a subsequent pregnancy.
RESULTS: This guideline details the population of pregnant individuals who may benefit from Rho(D) immune globulin (RhIG) immunoprophylaxis. Thus, those for whom the intervention is not required may avoid adverse effects, while those who are at risk of alloimmunization may mitigate this risk for themselves and/or their fetus.
METHODS: For recommendations regarding use of RhIG, Medline and Medline in Process via Ovid and Embase Classic + Embase via Ovid were searched using both the trials and observational studies search strategies with study design filters. For trials, the Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Database of Abstracts of Reviews of Effects via Ovid were also searched. All databases were searched from January 2000 to November 26, 2019. Studies published before 2000 were captured from the grey literature of national obstetrics and gynaecology specialty societies, luminary specialty journals, and bibliographic searching. A formal process for the systematic review was undertaken for this update, as described in the systematic review manuscript published separately.
METHODS: The authors rated the quality of evidence and strength of recommendations using the SOGC\'s modified GRADE approach. See Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).
UNASSIGNED: The intended users of this guideline include prenatal care providers such as obstetricians, midwives, family physicians, emergency room physicians, and residents, as well as registered nurses and nurse practitioners.
CONCLUSIONS: An updated Canadian guideline for prevention of Rh D alloimmunization addresses D variants, cffDNA for fetal Rh type, and updates recommendations on timing of RhIG administration.
CONCLUSIONS: RECOMMENDATIONS.