Management of red blood cell alloimmunization in pregnancy

Successful management of severe Kell alloimmunization in pregnancy with intravenous immune globulin

Hemolytic Disease of the Fetus and Newborn (HDFN) is a condition that affects 1 to 2 out of 1000 patients during pregnancy (1). When an alloantibody is present, it is essential to identify its nature in order to organize appropriate follow-up. Kell-mediated HDFN is rare; it occurs in about 5% of Kell alloimmunized pregnant women. It is important to note that in case of anti-Kell immunization, the severity of HDFN is not correlated with maternal antibody titers, and anemia tends to occur earlier and more severely. Therefore, early diagnosing and management of this condition is crucial. In the management of severe fetal anemia due to Kell immunization, available treatments include in utero transfusion (IUT), immunoglobulin therapy. Other alternative treatments exist, such as plasmapheresis. Intravenous immunoglobulin (IVIG), a noninvasive therapeutic approach, acts through multiple mechanisms. IVIG has been evaluated in cases of RhD immunization with high maternal antibody titers and a history of pregnancies involving early hydrops or intrauterine death. Regarding the potential benefits of intravenous IgG therapy, it may delay the need for early IUT, reduce the overall reliance on IUT, and have a positive impact on obstetric outcomes. This case of IV IgG therapy of anti-Kell immunization offers a thought-provoking avenue for future exploration.

Non-RhD alloimmunization in pregnancy: an updated review

RhD alloimmunization in pregnancy is still the main cause of hemolytic disease of the fetus and neonate (HDFN). Nevertheless, there are other antigens that may be associated with the occurrence of this phenomenon and that have been growing in proportion, given that current prevention strategies focus only on anti-RhD antibodies. Although not widespread, the screening and diagnostic management of the disease caused by these antibodies has recommendations in the literature. For this reason, the following review was carried out with the objective of listing the main red blood cell antigen groups described - such as Rh, ABO, Kell, MNS, Duffy, Kidd, among others - addressing the clinical importance of each one, prevalence in different countries, and recommended management when detecting such antibodies during pregnancy.

Effect of delayed cord clamping on red blood cell alloimmunization: a retrospective cohort study

BACKGROUND

Although delayed cord clamping has well-known benefits for preterm and term neonates, it has been inadequately assessed in alloimmunized neonates.

OBJECTIVE

This study aimed to evaluate the benefits and risks of delayed cord clamping in alloimmunized neonates.

STUDY DESIGN

This was a retrospective comparative pre-post cohort study conducted from 2003 to 2018 in a tertiary care center in France. All living singleton neonates whose mothers were followed up for red blood cell alloimmunization during gestation and confirmed at birth (N=224) were included. Neonates were either exposed to immediate (n=125) or delayed cord clamping (n=99). Our main outcome was the time from birth to first exchange transfusions and/or transfusions. Secondary outcomes were hemoglobin level at birth, rate of exchange transfusion, number of postnatal transfusions, maximum bilirubin level, and number of phototherapy hours.

RESULTS

Hemoglobin at birth was significantly higher in case of delayed cord clamping (mean difference, 1.7 g/dL; 95% confidence interval, 0.7-2.8). Among infants treated with exchange transfusion or transfusion, the time to initial treatment was higher in case of delayed cord clamping (median difference, 8 days; rate ratio, 1.51; 95% confidence interval, 1.09-2.10). There were no significant differences in the need for exchange transfusion, the number of transfusions, the maximum total bilirubin level, nor the number of phototherapy hours. In the subgroup analysis of neonates needing intrauterine transfusion during pregnancy (ie, severe alloimmunization), neonates had a lower rate of exchange transfusion in case of delayed cord clamping (odds ratio, 0.36; 95% confidence interval, 0.15-0.82).

CONCLUSION

Our results indicate a benefit of delayed cord clamping in alloimmunization, regardless of pathology severity, without increased risk of jaundice.

Anti-RH1 alloimmunization: At what maternal antibody threshold is there a risk of severe fetal anemia?

BACKGROUND

To define a threshold of maternal antibodies at risk of severe fetal anemia in patients followed for anti-RH1 alloimmunization (AI).

STUDY, DESIGN, AND METHODS

We conducted a retrospective study of patients followed for anti-RH1 AI at the Lille University Hospital. The first group, severe anemia, included patients who received one or more in utero transfusions (IUT) or who were induced before 37 weeks of pregnancy for suspected severe fetal anemia. The second group, absence of severe anemia, corresponded to patients without intervention during pregnancy related to AI. Sensitivities, specificities, and positive and negative predictive values for screening for severe fetal anemia were calculated for the antibody thresholds of 3.5 and 5 IU/ml for the quantification.

RESULTS

Between 2000 and 2018, 207 patients were included 135 in the severe anemia group and 72 in the no severe anemia group. No severe anemia was observed for an antibody titer below 16. For an antibody threshold of 3.5 IU/ml, the sensitivity was 98.2%, with 30.2% false positives. All severe anemias were detected in the second trimester; two cases of severe anemia were not detected in the third trimester. For an antibody threshold of 5 IU/ml, the sensitivity was lower at 95.6%, with five cases of severe anemia not detected.

CONCLUSION

The antibody threshold of 3.5 IU/ml for the quantification and 16 for the titration allow targeting patients requiring close monitoring by an experienced team in case of anti-RH1 AI.

Fetal and neonatal outcome in severe alloimmunization managed with intrauterine transfusion: 18-year experience in a tertiary referral hospital in China

Background

Hemolytic disease of the fetus and newborn (HDFN) due to red cell alloimmunization, is an important cause of fetal and neonatal morbidity and mortality. However, fetal and neonatal outcome of HDFN managed with intrauterine transfusion (IUT) in China are unknown. In addition, fetal and neonatal outcomes according to the type of maternal red cell alloantibodies involved and outcomes of hydrops fetalis are also unclear.

Objectives

The objective of this study was to evaluate fetal and neonatal outcomes of severe red-cell alloimmunization treated by IUT, to compare the outcomes according to the type of antibody, and to investigate the perinatal and postnatal outcomes of hydrops fetalis due to red cell alloimmunization.

Methods

A retrospective study of pregnancies affected by HDFN and managed with IUT at a tertiary care university hospital in China between January 2001 and December 2018 was performed. Fetal and neonatal outcomes were investigated, and comparison of outcomes depending on the type of antibody and comparison of outcome between hydrops fetalis and fetuses without hydrops were also conducted.

Results

244 IUTs were performed in 81 fetuses from 80 pregnancies. Anti-RhD was the major etiology of HDFN requiring IUT (71.6%). The fetal survival rate was 90.1%. The survival rate of the hydropic fetuses was significantly lower than those of the non hydropic fetuses (61.2% vs. 95.6%) (P = 0.002**). Compared with non hydropic fetuses, hydropic fetuses had significantly lower gestational age and lower hemoglobin level at first IUT. The neonatal survival rate was 98.6%. Exchange transfusions were required in 26% of the neonates. 30.1% of neonates had late anemia and required top-up transfusions, and hydropic fetuses required more late top-up transfusions than fetuses without hydrops. No significant difference in fetal and neonatal outcomes was found among the four subgroups stratified by the antibody involved.

Conclusion

Our study demonstrates that IUT is an effective and safe therapy for severe HDFN at our institution. Early detection and treatment of hydrops is critical for perinatal outcomes. Particular attention should be paid to late postnatal anemia in affected neonates and top-up transfusion is still commonly needed.

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

BACKGROUND

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.

METHODS

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).

RESULTS

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.

DISCUSSION

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.

Alloimmunization to Rh Antigen (D, C, E, C, E) Among Pregnant Women Attending Antenatal Care in South Western Uganda

INTRODUCTION

Maternal red cell alloimmunization to Rh antigen in pregnant women occurs when the immune system is sensitized by foreign red blood cell surface antigens, in this case fetal red blood cells, inducing an immune response. Various antigens of blood group systems may cause alloimmunization, especially the Rh, Kel, Fy, JK, and MNS systems. This study aimed to determine alloimmunization to the different frequencies of Rh antigen among pregnant women in South Western Uganda.

METHODS

A total of 1369 pregnant women consented and were recruited into a cross-sectional study during their regular antenatal visits during the period August 2020 to July 2021. Samples (4 mL) of anticoagulated and coagulated blood were obtained, and Rh blood grouping including Rh antigen and the indirect antiglobulin test (IAT) was carried out using the agglutination technology of the LISS ID-Card technique in the Ortho Biovue ID-Micro Typing System.

RESULTS

Out of 1369 participants recruited to the study, 78 (5.7%) were D-, 1291 were D+, and 134 (9.8%) had alloantibodies. Among those with alloantibodies, 115 (85.8%) were D+ and 19 (14.2%) D-. The percentage alloimmunization according to the Rh antigens was highest in e (9.72%), c (2.48%), C (2.34%) and E (0.94%) antigens. With the ABO system, alloimmunization was highest in blood group B (10.7%), followed by A (10.6%), O (9.2%) and then AB (7.1%). Alloimmunization was more prevalent in D- (24%) than in D+ participants (8.9%). Rhesus antigen e was the most prevalent antigen (99.8%), followed by c. The alloimmunization rate of 9.8% among these participants is high, and appears in both D+ and D- women. The other Rhesus antigens are seen to cause alloimmunization, with antigen e causing the highest prevalence. In conclusion, there is a need to identify antibodies and study the outcome for clinical significance, especially in D+ women, to facilitate proper pregnancy management.

ABO and Rh Antigen Distribution Among Pregnant Women in South Western Uganda

Introduction

ABO and Rh are the major blood group systems in Transfusion Medicine, the ABO system based on two red cell antigens (A, B) while the Rh has about 50 antigens of which five are highly clinically significant (D, C, c, E, e). These vary among races and ethnic groups. Blood type phenotype incompatibility between mother and fetus may result in antigen mismatch, triggering alloimmunization, and thus causing hemolytic transfusion reaction (HTR), which results in hemolytic disease of fetus and newborn (HDFN). This study aimed to determine the frequencies of ABO and rhesus blood group antigen in the pregnant women in South Western Uganda.

Methods

A cross-sectional study was carried out on 1369 pregnant women who were recruited and provided consent to participate during their regular antenatal visits between August 2020 and July 2021. Four milliliters (4mL) of EDTA-anti-coagulated blood samples were collected and ABO and Rh-blood grouping including Rh antigen screening was done using the agglutination technology comprised of glass beads and reagent contained in a column of the Ortho Biovue ID Micro Typing System (Ortho Clinical Diagnostics, New Jersey, USA). The Rh antigen phenotypes and frequencies were then determined.

Results

There was percentage distribution of 99.8%, c 99.3%, D 94.3%, C 19.2% and E 15.9%, with Rh cDe/cDe (65.1%) being the most common phenotype followed by cDe/CDe (15%), cDe/cDE (10.8%) and cDE/cDE 0.1% least common. The ABO grouping frequency was obtained as O 49.4%, A 29.5%, B 17.0% and AB 4.1%, with D positivity at 94.3%.

Discussion

Population genetic variations result in varied expressions of red cell antigens that may have clinical complications. Knowledge of the presence of these Rh antigen distributions and phenotype frequencies during pregnancy help in rational management of the pregnancy, alloimmunization and better approach to safe blood transfusion.

Red blood cell alloimmunization in pregnancy: A 10-year single-center study

Background/Aim. Pregnancy-induced red blood cell (RBC) alloimmunization is important not only because of the possible negative effects on subsequent pregnancy outcomes in case the fetus carries the antigen but also because of the optimal trans-fusion management in cases of obstetric hemorrhage. Timely detection of RBC antibodies is part of testing, prevention, and treatment strategy, aimed at achieving better outcomes for alloimmunized mothers with an affected fetus. The aim of the study was to determine the frequency and specificity of alloantibodies among pregnant women from the South Backa District, Serbia, with special attention to the incidence of anti-D alloantibodies. Methods. A retrospective study was conducted in the Blood Transfusion Institute of Vojvodina and covered the period from January 1, 2010, to December 31, 2019. Screening and antibody identification were performed by an indirect antiglobulin test in gel-microcards (ID-Card Liss/Coombs) with two test RBC (ID-DiaCell I-II screening cells, Bio-Rad, Cressier, Switzerland) on an automated system (IH-500, Bio-Rad). Results. Among 25,694 tested pregnant women, 1.38% were actively immunized, while 1.12% of women acquired antibodies in the current pregnancy. Among 3,622 (14.09%) RhD-negative women, 1.77% produced anti-D antibodies during the ongoing pregnancy. Distribution of anti-body specificity was: anti-D 23.34%, anti-M 11.85%, anti-E 9.41%, anti-K 9.41%, anti-C 5.92%, anti-Fyb 5.92%, anti-c 3.13%, anti-S 3.13%, anti-Lea 3.13%, anti-Leb 3.13%, anti-Cw 1.75%, anti-Jka 1.40%, anti-P 1.05%, anti-Lub 0.70%, anti-Fya 0.35%, autoantibody of undetermined specificity 0.70%, and irregular antibodies of undetermined specificity 15.68%. Conclusion. Immunoglobulin prophylaxis has led to a significant reduction in the frequency of D-alloimmunization among pregnant women in the South Backa District over the last ten years. However, the incidence of anti-D antibodies is still significantly higher than in published data for developed countries. We also identified the other, less commonly present, clinically significant antibodies. There is a need to introduce uniform recommendations for immunohematological testing in pregnancy on the territory of the Republic of Serbia in accordance with modern requirements.

Outcome predictors for maternal red blood cell alloimmunisation with anti-K and anti-D managed with intrauterine blood transfusion

Red blood cell (RBC) alloimmunisation with anti-D and anti-K comprise the majority of cases of fetal haemolytic disease requiring intrauterine red cell transfusion (IUT). Few studies have investigated which haematological parameters can predict adverse fetal or neonatal outcomes. The aim of the present study was to identify predictors of adverse outcome, including preterm birth, intrauterine fetal demise (IUFD), neonatal death (NND) and/or neonatal transfusion. We reviewed the records of all pregnancies alloimmunised with anti-K and anti-D, requiring IUT over 27 years at a quaternary fetal centre. We reviewed data for 128 pregnancies in 116 women undergoing 425 IUTs. The median gestational age (GA) at first IUT was significantly earlier for anti-K than for anti-D (24·3 vs. 28·7 weeks, P = 0·004). Women with anti-K required more IUTs than women with anti-D (3·84 vs. 3·12 mean IUTs, P = 0·036) and the fetal haemoglobin (Hb) at first IUT was significantly lower (51.0 vs. 70.5 g/l, P = 0·001). The mean estimated daily decrease in Hb did not differ between the two groups. A greater number of IUTs and a slower daily decrease in Hb (g/l/day) between first and second IUTs were predictive of a longer period in utero. Earlier GA at first IUT and a shorter interval from the first IUT until delivery predicted IUFD/NND. Earlier GA and lower Hb at first IUT significantly predicted need for phototherapy and/or blood product use in the neonate. In the anti-K group, a greater number of IUTs was required in women with a higher titre. Furthermore, the higher the titre, the earlier the GA at which an IUT was required in both groups. The rate of fall in fetal Hb between IUTs decreased, as the number of transfusions increased. Our present study identified pregnancies at considerable risk of an unfavourable outcome with anti-D and anti-K RBC alloimmunisation. Identifying such patients can guide pregnancy management, facilitates patient counselling, and can optimise resource use. Prospective studies can also incorporate these characteristics, in addition to laboratory markers, to further identify and improve the outcomes of these pregnancies.

Current perspective and scope of fetal therapy: part 2

Fetal therapy has been defined as any therapeutic intervention either invasive or noninvasive for correcting or treating any fetal malformation or condition. Invasive fetal therapy have its own set of maternal and fetal complications and invasive approach is not feasible in many of fetal conditions that are candidate for fetal therapy. Many such fetal conditions have been treated successfully by medical or noninvasive management. In medical fetal therapy, mothers are treated with medications which are transferred to fetus through placenta and exert positive effect on the fetus, thus avoiding complications that are seen secondary to invasive fetal therapy. The fetal conditions that have been managed with medical therapy includes fetal and neonatal alloimmune thrombocytopenia, neural tube defect, congenital adrenal hyperplasia, perinatal infections, respiratory distress syndrome, inborn error of metabolism, and congenital cystic adenomatoid malformation. This review will cover the medical or noninvasive aspect of fetal therapy and will highlight the progress made in the management of these fetal conditions.

Quantitative comparative analysis of human erythrocyte surface proteins between individuals from two genetically distinct populations

Red blood cells (RBCs) play a critical role in oxygen transport, and are the focus of important diseases including malaria and the haemoglobinopathies. Proteins at the RBC surface can determine susceptibility to disease, however previous studies classifying the RBC proteome have not used specific strategies directed at enriching cell surface proteins. Furthermore, there has been no systematic analysis of variation in abundance of RBC surface proteins between genetically disparate human populations. These questions are important to inform not only basic RBC biology but additionally to identify novel candidate receptors for malarial parasites. Here, we use 'plasma membrane profiling' and tandem mass tag-based mass spectrometry to enrich and quantify primary RBC cell surface proteins from two sets of nine donors from the UK or Senegal. We define a RBC surface proteome and identify potential Plasmodium receptors based on either diminished protein abundance, or increased variation in RBCs from West African individuals.