Hemolytic disease of the fetus and newborn: systematic literature review of the antenatal landscape

Why do people still make anti-D over 50 years after the introduction of Rho(D) immune globulin? A Biomedical Excellence for Safer Transfusion (BEST) Collaborative study

BACKGROUND

Rho(D) immune globulin (RhIg) is used to reduce RhD alloimmunization in pregnancy. This study describes potential causes for RhD alloimmunization after the development and implementation of RhIg.

STUDY DESIGN AND METHODS

This retrospective descriptive study investigated RhD-negative patients born in 1965-2005 with anti-D newly identified during 2018-2022. Transfusion, pregnancy, intravenous drug abuse, and transplantation were considered potential alloimmunization sources.

RESULTS

There were 1200 study patients (852 females; 348 males) at 30 institutions in 5 countries (USA, Canada, UK, New Zealand, Brazil). Most patients had a single potential source of alloimmunization identified (857/1200, 71%), most commonly pregnancy among females (537/852, 63%) and transfusion among males (180/348, 52%). When multiple potential sources were included, males were more likely than females to have a history of transfusion (235/348 [68%] vs. 149/852 [17%], p < .0001) and confirmed or suspected intravenous drug abuse (100/348 [29%] vs. 138/852 [16%], p < .0001). Among females with a history of pregnancy, 119/718 (17%) had healthcare access issues, 120/718 (17%) had pregnancy in a country where they may not have received RhIg, and 21/718 (3%) refused RhIg. Among patients with a history of transfusion, males were more likely than females to have received RhD-positive red blood cells or whole blood (143/235 [61%] vs. 30/149 [20%], p < .0001) and/or platelets (84/235 [36%] vs. 19/149 [13%], p < .0001).

DISCUSSION

Pregnancy was the most frequently identified potential source of RhD alloimmunization among females. Transfusion was most frequent in males. Intravenous drug abuse as a common potential source among patients with RhD alloimmunization merits further study.

Targeting the Neonatal Fc Receptor in Autoimmune Diseases: Pipeline and Progress

Autoimmune diseases are highly prevalent and affect people at all ages, women more often than men. The most prominent immunological manifestation is the production of antibodies directed against self-antigens. In many cases, these antibodies (Abs) drive the pathogenesis by attacking the body's own healthy cells, causing serious health problems that may be life threatening. Most autoantibodies are of the immunoglobulin G (IgG) isotype, which has a long plasma half-life and potent effector functions. Thus, there is a need for specific treatment options that rapidly eliminate these pathogenic IgG auto-Abs. In this review, we discuss how the neonatal Fc receptor (FcRn) acts as a regulator of the high levels of not only IgG Abs, but also albumin, by rescuing both these soluble proteins from cellular catabolism, and how a molecular and cellular understanding of this complex biology has spurred an intense interest in the development of FcRn-targeting strategies for the treatment of IgG-driven autoimmune diseases. We find that this emerging therapeutic class demonstrates efficacy within several autoimmune diseases with distinct pathophysiology. This offers hope for both new therapeutic avenues for highly prevalent diseases currently treated by other means, and rare diseases with no approved therapies to date. In addition, we elaborate on studies that have led to approval of the first FcRn antagonists, the clinical progress and structural design of molecules in the pipeline, their position in the overall therapeutic landscape of autoimmunity, the design of next-generation antagonists as well as the use of this receptor-targeting principle for other therapeutic applications.

Prevalence and clinical implications of unexpected red blood cell antibodies in a tertiary care hospital in Sri Lanka

Unexpected red blood cell (RBC) alloantibodies can lead to hemolytic transfusion reactions and hemolytic disease of the fetus and newborn (HDFN). Screening for these antibodies is essential to ensure transfusion safety and improve patient care. Prevalence and frequency of unexpected antibodies vary among populations, influenced by genetic and demographic factors. This study addresses the gap in data specific to University Hospital, General Sir John Kotelawala Defence University. A retrospective analysis was performed on 20,212 patients (40.74% pregnant women and 59.25% transfusion recipients) from November 2019 to August 2024, assessing the prevalence, distribution, and clinical relevance of RBC alloantibodies. The study found that 0.80 percent of patients were alloimmunized and 28.87 percent of the antibodies were clinically significant. Common antibodies included anti-Leb (27.27%) and anti-Lea (19.25%); anti-D was the most frequent among Rh antibodies. A significantly higher proportion of pregnant women were alloimmunized compared with transfusion recipients (p < 0.000). Among D- pregnant women, 5.45 percent were alloimmunized, mainly with anti-D. HDFN was identified with either maternal anti-D or anti-E. These findings emphasize the need for early antibody detection and monitoring to enhance transfusion safety, suggesting policy improvements for antibody screening in transfusion and antenatal care in Sri Lanka.

Fetal Hydrops: Genetic Dissection of an Unspecific Sonographic Finding-A Comprehensive Review

Fetal hydrops is defined as the presence of abnormal fluid collections in two or more intra-fetal compartments. It has been classified based on etiology (immune vs. non-immune), on the presence or absence of other findings (isolated vs. non-isolated) and on the gestational age at presentation (first-, second- or third-trimester). In all cases of non-immune hydrops fetalis, invasive prenatal diagnosis is offered. However, after cytogenetic analyses, 80% of fetuses remain without etiological diagnosis, not allowing one to define the prognosis and to formulate recurrence risks. Several geneticists recommend performing either a next-generation sequencing panel (commonly limited to RASopathy testing) or exome sequencing, if cytogenetic tests are inconclusive. In the literature, the data are extremely heterogeneous, due to the differences in these indications and the limitation of study to a select group of genes. The identification of the underlying cause is crucial, as prognostic information and even therapy options are becoming increasingly available for a wide and growing array of genetic conditions. A systematic approach would allow an overall evaluation of the diagnostic rate of the exome sequencing in fetal effusions, also calculating the prevalence of associated diseases, with the aim of obtaining a diagnosis, defining the most appropriate management for each case, and broadening the spectrum of conditions known to be associated with hydrops.

Patient experience and burden of haemolytic disease of the foetus and newborn: a systematic review

BACKGROUND

Haemolytic disease of the foetus and newborn (HDFN) is an immune disorder driven by maternal alloimmunisation against foetal/newborn red blood cell antigens. HDFN can cause significant morbidity and mortality, with symptoms in the foetus ranging from mild anaemia to hydrops fetalis. While in newborns, HDFN can lead to severe forms of neonatal hyperbilirubinaemia and kernicterus. This systematic review (SR) aimed to identify and summarise real-world evidence (RWE) related to the patient burden/experience and economic burden of HDFN.

METHODS

Electronic database searches supplemented by handsearching of grey literature, were conducted to identify studies that reported the clinical patient burden/experience, and economic burden of HDFN in Europe, the Middle East, and Africa (EMEA). Data from eligible studies were summarised in a narrative synthesis due to heterogeneity between studies.

RESULTS

A total of 26 relevant publications were identified for inclusion in the SR, consisting of one study that directly measured Health Related Quality of Life, 9 studies reporting on proxy outcomes for patient burden and 18 studies reporting on economic burden (this includes two double-counted studies reporting more than one outcome type). Neurodevelopment, academic development, behaviour and personality were assessed as proxy outcomes for patient burden given the limited identification of patient-reported outcome data. These studies suggested potential neurodevelopmental impairments in children with HDFN. Despite these indirect insights into patient burden, identified data were limited and results should be interpreted with consideration of the inherent heterogeneity in design and endpoints assessed across RWE studies. Economic burden data were primarily limited to healthcare resource use outcomes, with limited reported data on healthcare costs, it is difficult to draw notable conclusions on the true economic burden of HDFN.

CONCLUSIONS

The current SR provides a clear summary of the available evidence for the patient experience and economic burden of HDFN. While the limited evidence indicates that HDFN does confer a significant burden on patients, the review identifies the need for further well-powered and representative observational studies using well-defined outcome measures to aid a greater understanding of the burden and experience of HDFN.

TRIAL REGISTRATION

The protocol for this systematic review was registered in PROSPERO CRD42022328444.

Hemoglobin Electrophoresis versus Kleihauer-Betke to Determine Bone Marrow Suppression in Fetuses Undergoing Intrauterine Transfusion

OBJECTIVE

 Mainstay therapy for fetuses affected by maternal red cell alloimmunization is serial intrauterine transfusion (IUT). Testing to determine when fetal red cells have been replaced with donor cells historically involves the use of the Kleihauer-Betke (KB) test. Hemoglobin (Hgb) electrophoresis testing may be more rapid with a reduced cost of analysis. We aimed to determine the correlation between fetal Hgb electrophoresis versus the traditional KB test.

STUDY DESIGN

 This is a retrospective analysis of all alloimmunized singleton pregnancies undergoing IUT between January 1, 2021, and July 1, 2023. Maternal and fetal characteristics were collected along with the indication for IUT. A final fetal blood sample was obtained at the conclusion of each transfusion and sent for KB testing and Hgb electrophoresis. The primary outcome was the assessment of these parameters in their ability to predict the replacement of the fetal circulating red cell population with donor cells. Linear regression analysis and repeated measures analysis of variance were performed, and p-values less than 0.05 were considered significant.

RESULTS

 A total of 56 IUTs were performed in 16 patients. There were 39 (69.6%) final KB test values collected and compared with 30 (53.6%) final Hgb electrophoresis values. Hgb electrophoresis when compared with the KB test demonstrated a significant correlation (R 2 = 0.93; 95% confidence interval, 0.61-0.76; p < 0.001). This same finding held true when examining the correlation at each individual IUT as well. The final KB test and Hgb electrophoresis values significantly decreased with each transfusion (p = 0.003). A predominance of adult donor blood was noted by the third transfusion for both laboratory indices.

CONCLUSION

 Fetal Hgb electrophoresis obtained at the time of IUT demonstrates a significant correlation with the traditional KB test.

KEY POINTS

· Fetal Hgb electrophoresis following IUT is underexplored. · Hgb electrophoresis is an automated evaluation. · The traditional KB test is a manual evaluation. · These two tests demonstrate significant correlation.

Hemolytic disease of the fetus and newborn and Rhesus alloimmunization in Latin American countries: a scoping review

BACKGROUND

Hemolytic disease of the fetus and newborn (HDFN) is a condition due to maternal blood group antibodies targeting antigens in fetal red blood cells, with significant prenatal/perinatal morbidity and mortality. Severe HDFN cases are often associated with alloimmunization against Rhesus D (RhD) or Kell antigens. Information about HDFN epidemiology and treatment in Latin American countries is limited. This review aims to identify and synthesize the available evidence on the epidemiology and management of HDFN in this region.

METHODS

In July 2023, EMBASE, PubMed, LILACS, and other databases were searched for articles reporting epidemiology, treatment, prenatal and perinatal outcomes, and patient journey of HDFN cases in Latin American countries. A snowball search of cross-references and gray literature complemented the initial search. Publications in English, Spanish, and Portuguese were reviewed. Data were extracted using a defined template and charted in tables.

RESULTS

We reviewed five guidelines and 19 observational studies from Brazil, Chile, Mexico, Argentina, Colombia, Panamá, Paraguay, and Peru. HDFN due to Rh alloimmunization ranged from 0.5 to 5 per 1000 live births, and anti-D remains the most frequent alloantibody type for severe HDFN. The perinatal mortality rate of HDFN is approximately 1.3-1.6 per 100,000 live births, and fetal deaths can reach 30% among patients treated with intrauterine transfusions. Up to 47% of alloimmunized pregnancies were referred to reference centers only during the third trimester. About 60% of eligible pregnancies received anti-D IgG prophylaxis.

CONCLUSIONS

Although estimates in LATAM countries are scarce and lack standardized measures, we observed that the incidence, morbidity, and mortality of HDFN in this region are problematic. RhD alloimmunization was reported in approximately up to 70% of severe HDFN cases, despite anti D HDFN being largely preventable.

Analysis of pregnancy and neonatal outcomes in 100 pregnant women with Rh-negative blood type

BACKGROUND

This study aimed to explore variations in prenatal care, delivery methods, influencing factors, and neonatal outcomes among Rh-negative pregnant women, so as to improve pregnancy healthcare for this demographic, raise the quality of maternal-fetal management, and safeguard the health of both mother and infant.

METHODS

This study included 200 women who received routine prenatal care, exhibited no other pregnancy complications, and were admitted for delivery. They were divided into an observation group (100 Rh-negative blood type) and a control group (100 Rh-positive blood type). The study examined differences in pregnancy management, clinical characteristics and pregnancy outcomes between the two groups.

RESULTS

The results indicated that singleton pregnancies in Rh-negative mothers are associated with significantly higher rates of postpartum blood loss (305.1 ± 183.8 vs. 246.1 ± 84.9 mL, P = 0.004), neonatal hyperbilirubinemia (39% vs. 23%, P = 0.014), low birth weight (11% vs. 2%, P = 0.01), and NICU admission (30% vs. 18%, P = 0.046) compared to the control group. Among Rh-negative mothers, subgroup analysis by ethnicity revealed a higher incidence of fetal distress in the other ethnic groups compared to the Han and Zhuang groups (16.7%, 0, 6.5%, respectively, P = 0.025). Subgroup analysis based on ABO blood type within Rh-negative mothers did not show any statistical significance in various outcomes (all P > 0.05). Infants with neonatal hyperbilirubinemia born to Rh-negative mothers experienced a quicker resolution of hyperbilirubinemia compared to those whose mothers did not receive intramuscular anti-D immunoglobulin [1.0 (1.0, 1.5) vs. 5.0 (1.5, 10.0), P = 0.002].

CONCLUSIONS

The Rh-negative blood type is linked to higher risks of neonatal hyperbilirubinemia, low birth weight, and increased postpartum hemorrhage, resulting in detrimental pregnancy outcomes. Administering anti-D immunoglobulin speeds up the resolution of neonatal hyperbilirubinemia. Thus, prudent and efficient use of anti-D immunoglobulin can mitigate adverse outcomes for both mothers and newborns.

Metabolomics-based study on the significance of differential metabolite binding IgG isoforms in Hemolytic disease of newborn

BACKGROUND

Hemolytic disease of the newborn (HDN) is a common condition that can have a severe impact on the health of newborns due to the hemolytic reactions it triggers. Although numerous studies have focused on understanding the pathogenesis of HDN, there are still many unanswered questions.

METHODS

In this retrospective study, serum samples were collected from 15 healthy newborns and 8 infants diagnosed with hemolytic disease. The relationship between different metabolites and various IgG subtypes in Healthy, HDN and BLI groups was studied by biochemical technique and enzyme-linked immunosorbent assay (ELISA). Metabolomics analysis was conducted to identify the differential metabolites associated with HDN. Subsequently, Pearson's correlation analysis was used to determine the relation of these differential metabolites with IgG isoforms. The relationship between the metabolites and IgG subtypes was observed after treatment.

RESULTS

The study results revealed that infants with hemolytic disease exhibited abnormal elevations in TBA, IgG1, IgG2a, IgG2b, IgG3, and IgG4 levels when compared to healthy newborns. Additionally, differences in metabolite contents were also observed. N, N-DIMETHYLARGININE showed negative correlations with TBA, IgG1, IgG2a, IgG2b, IgG3, and IgG4, while 2-HYDROXYBUTYRATE, AMINOISOBUTANOATE, Inosine, and ALLYL ISOTHIOCYANATE exhibited positive correlations with TBA, IgG1, IgG2a, IgG2b, IgG3, and IgG4. Through metabolomics-based research, we have discovered associations between differential metabolites and different IgG isoforms during the onset of HDN.

CONCLUSION

These findings suggest that changes in metabolite and IgG isoform levels are linked to HDN. Understanding the involvement of IgG isoforms and metabolites can provide valuable guidance for the diagnosis and treatment of HDN.

Variations in antenatal management and outcomes in haemolytic disease of the fetus and newborn: an international, retrospective, observational cohort study

BACKGROUND

Advances in haemolytic disease of the fetus and newborn have led to numerous treatment options. We report practice variations in the management and outcomes of haemolytic disease of the fetus and newborn in at-risk pregnancies.

METHODS

In this international, retrospective, observational cohort study, data from cases with moderate or severe haemolytic disease of the fetus and newborn were retrieved from 31 centres in 22 countries. Eligible participants had pregnancies with haemolytic disease of the fetus that led to fetal death at 16 + 0 weeks or later, those treated antenatally with intrauterine transfusion or intravenous immunoglobulins, or neonates without antenatal treatment who were treated with intensive phototherapy, exchange transfusion, or red blood cell transfusions. All patients had confirmed maternal alloantibodies and an antigen-positive fetus incompatible with the maternal alloantibody. Patients with ABO-incompatibility only were excluded. We assessed serological diagnostics and referrals, antenatal treatment and timing, complications, delivery route, and gestational age at birth. Outcomes were analysed in all eligible participants who had complete data available.

FINDINGS

2443 pregnancies with haemolytic disease of the fetus and newborn treated between Jan 1, 2006, and July 1, 2021, were shared by the centres and analysed between Dec 1, 2021, and March 1, 2023. 23 pregnancies were excluded due to missing information and we included 2420 for further analysis. 1764 (72·9%) of 2420 pregnancies were affected by D-antibodies. 95 (3·9%) of 2420 pregnancies resulted in fetal death. Of the 2325 liveborn neonates, 1349 (58·1%) received any form of antenatal treatment and 976 (41·9%) were only treated postnatally. Median gestational age at referral was 20·4 weeks (IQR 14·9-28·0) and ranged between medians of 10·0 and 26·3 weeks between centres. Severe hydrops at first intrauterine transfusion was present in 185 (14·5%) of 1276 pregnancies, with proportions ranging between 0 and 42% between centres. A median of two intrauterine transfusions (IQR 1-4) were done per pregnancy. The fetal access sites used in intrauterine transfusions varied widely between centres. Non-lethal complications in intrauterine transfusions by transfusion site occurred at a lower rate in intrahepatic approaches (2·0%, 95% CI 1·1-3·3) than in placental insertion (6·9%, 5·8-8·0) and free loop (13·3%, 8·9-18·9). The use and indication for intravenous immunoglobulin administration varied widely. Neonates with intrauterine transfusion were born at a median gestational age of 35·6 weeks (IQR 34·0-36·7), ranging between medians of 33·2 and 37·3 weeks between centres, while neonates without antenatal treatment were born at a median gestational age of 37·3 (IQR 36·3-38·1), ranging between medians of 34·9 and 38·9 weeks between centres.

INTERPRETATION

We found considerable variation in antenatal management and outcomes in haemolytic disease of the fetus and newborn between sites in different countries. Our study shows the capacity of the field to gather valuable data on a rare disease and to optimise care.

FUNDING

None.

Biphasic Behavior of Anti-M Antibody and Hemolytic Disease of the Fetus and Newborn (HDFN)

The anti-M antibody is a cold, naturally occurring immunoglobulin M (IgM) antibody that is generally considered clinically insignificant and often overlooked in transfusion practices and assessments of patients at risk for hemolytic disease of the fetus and newborn (HDFN). However, the presence of an IgG component in this case renders the antibody clinically significant, underscoring the necessity for proper serologic testing during prenatal evaluations. We present a case involving an anti-M antibody with an IgG component to highlight the critical importance of thorough serologic testing during prenatal testing.

Characterization of blood bank and transfusion medicine practices for pregnant individuals with fetuses at risk of hemolytic disease in the United States

BACKGROUND

Hemolytic disease of the fetus and newborn (HDFN) is caused by maternal alloantibody-mediated destruction of fetal/neonatal red blood cells (RBCs). While the pathophysiology has been well-characterized, the clinical and laboratory monitoring practices are inconsistent.

METHODS

We surveyed 103 US institutions to characterize laboratory testing practices for individuals with fetuses at risk of HDFN. Questions included antibody testing and titration methodologies, the use of critical titers, paternal and cell-free fetal DNA testing, and result reporting and documentation practices.

RESULTS

The response rate was 44% (45/103). Most respondents (96%, 43/45) assess maternal antibody titers, primarily using conventional tube-based methods only (79%, 34/43). Among respondents, 51% (23/45) rescreen all individuals for antibodies in the third trimester, and 60% (27/45) perform paternal RBC antigen testing. A minority (27%, 12/45) utilize cell-free fetal DNA (cffDNA) testing to predict fetal antigen status. Maternal antibody titers are performed even when the fetus is not considered to be at risk of HDFN based on cffDNA or paternal RBC antigen testing at 23% (10/43) of sites that assess titers.

DISCUSSION

There is heterogeneity across US institutions regarding the testing, monitoring, and reporting practices for pregnant individuals with fetuses at risk of HDFN, including the use of antibody titers in screening and monitoring programs, the use of paternal RBC antigen testing and cffDNA, and documentation of fetal antigen results. Standardization of laboratory testing protocols and closer collaboration between the blood bank and transfusion medicine service and the obstetric/maternal-fetal medicine service are needed.

Use of Therapeutic Plasma Exchange and Intravenous Immunoglobulin to Prevent Complications in a K+ Sensitized Pregnancy

The K antigen is a major cause of hemolytic disease of the fetus and newborn (HDFN). K-HDFN is unique in that it can result in destruction of not just mature erythrocytes but fetal erythrocyte progenitors, causing severe fetal anemia earlier in pregnancy than other antigens. This poses a danger to fetal health as intrauterine transfusion (IUT), the preferred method of managing HDFN, becomes riskier earlier in pregnancy. This report follows a K-negative mother managed with an alternative treatment, designed to delay the need for IUT.  The patient is a 32-year-old K-negative female, G2P1001, sensitized against K by her previous pregnancy with a 256 anti-K antibody titer. To prevent HDFN, she opted for preventative treatment to lower her immune response. She received three rounds of therapeutic plasma exchange, which lowered her titer to 64, followed by weekly IVIG administration at a dosage of 1g/kg body weight. Fetal anemia was monitored via middle cerebral artery Doppler imaging. The fetus did require two IUTs; however, they were not required until the third trimester. A healthy baby was delivered at 36 weeks with mild anemia and a positive direct antiglobulin test. The standard of care for K-sensitized pregnancies involves watchful waiting and correction of anemia with IUT. However, K-HDFN, if untreated, can cause severe anemia in early pregnancy when IUT is less viable. This case study joins a handful of others in reported literature where a K-sensitized pregnancy was treated prophylactically with immune-modulating therapies and argues that these treatments deserve further recognition and study.

RhD-Alloimmunization in Adult and Pediatric Trauma Patients

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

Colombian consensus for the diagnosis, prevention, and management of Rhesus disease

Objective

To train healthcare professionals involved in the care of Rh-D negative pregnant women, with the aim of standardizing the management of Rh isoimmunization prevention, timely antenatal diagnosis of Rh disease, fetal assessment, and treatment of fetuses with Rh disease, in order to prevent adverse perinatal outcomes.

Materials and Methods

A group of 23 expert panelists participated in the development of the consensus through three rounds, answering a questionnaire consisting of 8 domains and 22 questions. A modified Delphi method was used until the consensus threshold among participants was reached, defined as 80% or greater agreement in responses. In the third round of the expert panel, a twenty-third question emerged, which was answered by one of the thematic leaders. The eight domains of antenatal management for Rh-D negative pregnant women were: 1) Rh-D determination, 2) initial prenatal care for Rh-D negative patients, 3) titration and periodicity of the indirect Coombs test, 4) sensitizing events, 5) administration of anti-D immunoglobulin (IgG), 6) Doppler velocimetry of the middle cerebral artery (MCA), 7) antenatal management of isoimmunized patients and anemic fetuses, and 8) timing for pregnancy termination based on different clinical scenarios. Based on these responses, and a review of international clinical practice guidelines, consensus statements were formulated, including recommendations, their justification, and adaptation to the local context.

Results

The following recommendations were issued: It is suggested that Rh-D negative women of childbearing age attend a preconception consultation. It is recommended to determine maternal Rh-D status at the first contact with health services, either during the preconception consultation or at the first prenatal check-up. For Rh-D negative patients, it is recommended to determine the Rh-D status of the child's father during prenatal care as early as possible, preferably before the 28th week of gestation. For Rh-D negative primigravidas, where the father is Rh-D positive, it is suggested to: a) determine and quantify Rh-D antibodies (indirect Coombs test) during the first consultation and then quarterly, b) expand the obstetric history, with an emphasis on identifying sensitizing events, and c) provide parental counseling regarding potential risks, the need for additional tests, and the possibility of immunization during pregnancy. During prenatal care for Rh-D negative multiparous patients with previous Rh-D positive offspring, the initial approach should include: a) determining and titrating Rh-D antibodies (indirect Coombs test); b) expanding the obstetric history, focusing on sensitizing events; and c) providing parental counseling about potential risks and additional tests. After a sensitizing event, it is recommended to administer anti-D IgG within the first 72 hours at a dose of 1500 IU (300 μg). If not feasible, it can be administered up to 4 weeks after the event if it was not given initially. 7.1. For non-isoimmunized pregnant women (with a negative Coombs test and Rh-positive newborn), it is recommended to administer anti-D IgG between weeks 28 and 32, and within the first 72 hours postpartum if the newborn is Rh-positive. The dose is 300 μg IM or IV. 7.2. In the case of a cesarean section in an Rh-D negative patient with a Rh-D positive child, the consensus does not recommend doubling the dose of anti-D IgG. The dose remains the same as after a vaginal delivery: 300 μg IM or IV. 7.3. In a twin delivery involving an Rh-D negative patient with two or more Rh-D positive live-born infants, the consensus recommends not doubling the dose of anti-D IgG. The dose remains 300 μg IM or IV, the same as after a vaginal delivery. 7.4. For a non-isoimmunized Rh-D negative patient in the puerperium with immediate postpartum surgical tubal sterilization and an Rh-D positive neonate, anti-D IgG is recommended, assuming no prior sensitization, given the potential for reproductive decision changes or failure of the procedure. An Rh-D negative patient is considered isoimmunized if: a) the indirect Coombs test is positive at any titer, provided anti-D IgG was not received in the previous month, or b) there is a history of adverse perinatal outcomes associated with Rh disease in prior pregnancies, such as hydrops. 9.1. If Rh-D negative women are isoimmunized, it is necessary to determine the anti-D antibody titer, as this titer correlates with the severity of the disease and determines the need for fetal anemia studies with Doppler velocimetry of the MCA. 9.2. For isoimmunized Rh-D negative patients, it is recommended to follow up with monthly quantitative indirect Coombs tests until week 24, then bi-weekly, or until reaching a critical titer (≥ 1:16). 10.1. Doppler ultrasound of the MCA is suggested for Rh-D negative patients with a positive indirect Coombs test and titers ≥ 1:16. 10.2. In non-isoimmunized Rh-D negative patients, the consensus does not recommend MCA Doppler velocimetry. 10.3. Weekly MCA Doppler ultrasounds are recommended for isoimmunized patients with indirect Coombs titers ≥ 1:16. 10.4. The consensus suggests adopting a cut-off value of ≥ 1.5 multiples of the median (MoM) of the peak systolic velocity for gestational age on MCA Doppler, as this value best correlates with fetal anemia. The consensus suggests Cordocentesis when fetal anemia is suspected, and intrauterine fetal transfusion when cordocentesis shows severe fetal anemia. This procedure should be performed by trained personnel. It is recommended to prolong pregnancy until the fetus has achieved sufficient lung and tissue maturation to improve perinatal survival, according to the indirect Coombs test titer threshold.

Conclusions

It is essential to address Rh-D negative pregnant women, isoimmunized women, and fetuses with Rh disease in an appropriate and standardized manner, according to the Colombian context, across all levels of prenatal care. The recommendations issued in this consensus are expected to improve clinical care, as well as enhance perinatal health and neonatal quality of life in cases of Rh disease.

Global prevalence of hereditary thrombotic thrombocytopenic purpura determined by genetic analysis

ABSTRACT

Hereditary thrombotic thrombocytopenic purpura (hTTP) is a rare autosomal recessive, life-threatening disorder caused by a severe deficiency of the plasma enzyme, ADAMTS13. The current estimated prevalence of hTTP in different regions of the world, 0.5 to 2.0 patients per million, is determined by the frequency of diagnosed patients. To evaluate more accurately the worldwide prevalence of hTTP, and also the prevalence within distinct ethnic groups, we used data available in exome and genome sequencing of 807 162 (730 947 exomes, 76 215 genomes) subjects reported recently by the Genome Aggregation Database (gnomAD-v4.1). Among 1 614 324 analyzed alleles in the gnomAD population we identified 6321 distinct ADAMTS13 variants. Of these, 758 were defined as pathogenic; 140 (18%) variants had been previously reported and 618 (82%) were novel (predicted as pathogenic). In total 10 154 alleles (0.6%) were carrying the reported or predicted pathogenic variants; 7759 (77%) with previously reported variants. Considering all 758 pathogenic variants and also only the 140 previously reported variants, we estimated a global hTTP prevalence of 40 and 23 cases per 106, respectively. Considering only the 140 previously reported variants, the highest estimated prevalence was in East Asians (42 per 106). The estimated prevalences of other populations were: Finnish, 32 per 106; non-Finnish Europeans, 28 per 106; Admixed Americans, 19 per 106; Africans/African Americans, 6 per 106; and South Asians, 4 per 106. The lowest prevalences were Middle Eastern, 1 per 106 and Ashkenazi Jews, 0.7 per 106. This population-based genetic epidemiology study reports that hTTP prevalence is substantially higher than the currently estimated prevalence based on diagnosed patients. Many patients with hTTP may not be diagnosed or may have died during the neonatal period.

Management and Treatment Outcomes of Hemolytic Disease of the Fetus and Newborn (HDFN)-A Retrospective Cohort Study

Background: Hemolytic disease of the fetus and newborn (HDFN) is caused by maternal antibodies attacking fetal blood cell antigens. Despite routine antenatal anti-D prophylaxis, intrauterine transfusions (IUTs) are still needed in some HDFN cases. Methods: We conducted a retrospective cohort study on newborns with HDFN born in the 1st Department of Obstetrics and Gynecology of the Medical University of Warsaw. We analyzed 274 neonates with HDFN, identifying 46 who required IUT due to fetal anemia and 228 who did not. The laboratory results, management, and outcomes were compared between these groups. Results: Comparative analysis showed that newborns treated with IUT were more likely to have significant anemia, hyperbilirubinemia, and iron overload, indicated by a high ferritin concentration. These neonates more often required top-up transfusions, phototherapy, intravenous immunoglobulin infusions, and exchange transfusions. The length of stay was longer for newborns who received IUT. Conclusions: HDFN requiring IUT is associated with a greater number of complications in the neonatal period and more often requires additional treatment compared to HDFN not requiring IUT.

A tale of two societies: implications of conflicting Rh-immunoglobulin guidelines

National guidance conflicts regarding the use of RhD immune globulin administration <12w. Recent Society for Maternal Fetal Medicine (SMFM) guidelines suggest liberal use of this product while other guidelines, including Society of Family Planning and the World Health Organization, propose a more conservative approach. Medicine is not practiced in a vacuum, and potential harms must include not only individual but communal and public health effects. We aim to critically examine the practical implications of the new SMFM guidelines with a focus on equity and access.

Why do RhD negative pregnant women still become anti-D immunized despite prophylaxis with anti-D immunoglobulin?

Maternal allo-anti-D in RhD negative pregnant women may cause mild to severe hemolytic disease of the fetus and newborn. Although several other antibodies may also destroy red blood cells of the fetus and newborn, preventive measures with anti-D immunoglobulin are only available for D antigen. Targeted antenatal care together with postpartum prophylaxis with anti-D immunoglobulin has significantly reduced the D-alloimmunization risk. Potentially sensitizing events like trauma to the pregnant abdomen, vaginal bleeding, and amniocentesis may lead to fetomaternal hemorrhage and necessitate additional doses. Despite comprehensive programs with these targeted measures, allo-anti-D is still the most common reason for severe hemolytic disease of the fetus and newborn. Where do we fail then? Here, in this review, I would therefore like to discuss the reasons for D-alloimmunizations hoping that the greater focus will pave the way for further reduction in the number of pregnancy-related allo-anti-Ds.

Clinical Management of Hydrops Fetalis in a Premature Neonate in India: A Case Report

Hydrops fetalis has classically been defined as the presence of extracellular fluid in at least two fetal body compartments. This fluid collection includes skin edema (> 5 mm thickness), pericardial effusion, pleural effusion, and ascites. Here we present a case of a 29-year-old female with antenatally diagnosed severe hydrops fetalis which was postnatally successfully managed. Despite recent advances, immune hydrops are still a challenge for healthcare workers in third-world nations.

Receipt of RhD-positive whole blood for life-threatening bleeding in female children: A survey in alloimmunized mothers regarding minimum acceptable survival benefit relative to risk of maternal alloimmunization to anti-D

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.

STUDY DESIGN AND 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).

CONCLUSION

Alloimmunized mothers would accept the risk of D-alloimmunization in a RhD-negative female child for improved survival in cases of life-threatening bleeding.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

DISCUSSION

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

Intrauterine Transfusion for Rhesus Alloimmunization: A Historical Retrospective Cohort from A Single Reference Center in Brazil

Objective: This study aimed to describe the historical experience of a single reference center in Brazil with intrauterine transfusion (IUT) for Rhesus (Rh) alloimmunization, evaluating the major complications and the perinatal outcomes of this procedure. Methods: This retrospective cohort study evaluated data from medical records of pregnant women between 20 and 34 weeks of gestation whose fetuses underwent IUT by cordocentesis between January 1991 and June 2021. The same experienced examiner performed all procedures. Univariate and multivariate logistic regression was used to assess the effect of fetal hydrops, duration of IUT, post-transfusion cord bleeding time, and bradycardia on death (fetal or neonatal). Results: We analyzed data from 388 IUTs in 169 fetuses of alloimmunized pregnant women with a mean age of 29.3 ± 5.1 years. Death and fetal hydrops were significantly associated at first IUT (p < 0.001). We had two cases of emergency cesarean section (mean of 0.51% per IUT) and three cases of premature rupture of the ovular membranes (mean of 0.77% per procedure). Thirty-six deaths were recorded, including 14 intrauterine and 22 neonatal. A higher percentage of neonatal deaths was observed in the group with post-transfusion cord bleeding time > 120 s (45.8%). The odds of neonatal death were 17.6 and 12.9 times higher in cases with hydrops and bradycardia than in cases without hydrops and bradycardia, respectively. The odds of death (fetal and neonatal) were 79.9 and 92.3 times higher in cases with hydrops and bradycardia than in cases without hydrops and bradycardia, respectively. Conclusions: The most common complications of IUT for Rh alloimmunization were post-transfusion cord bleeding, fetal bradycardia, premature rupture of ovular membranes, and emergency cesarean section. The IUT complication most associated with death (fetal and neonatal) was bradycardia, and the perinatal outcomes were worse in fetuses with hydrops.

How do we perform intrauterine transfusions?

BACKGROUND

Intrauterine transfusion (IUT) is an invasive but critical and potentially life-saving intervention for severe fetal anemia with demonstrated improvement in outcomes. The fetus is vulnerable to hemodynamic alterations and transfusion-related adverse events; therefore, special consideration must be given to blood component selection and modification. There is widespread IUT practice variability, and existing guidance primarily relies on expert opinion and single center experiences.

STUDY DESIGN AND METHODS

Experts in Maternal Fetal Medicine, Pediatric Hematology, and Transfusion Medicine from centers across the United States, collectively performing about 120 IUT annually, offer a multidisciplinary perspective on the performance of IUT and preparation of blood components. This perspective includes strategies for identifying an at-risk fetus, communicating between disciplines, determining the necessary blood volume, selecting and processing blood components, documenting the procedure in medical record, and managing the neonate.

RESULTS

Identifying an at-risk fetus relies on review of the clinical history, non-invasive monitoring, and laboratory evaluation. We recommend the use of relatively fresh, group O, cytomegalovirus-safe, freshly irradiated, red blood cells (RBC) that are Hemoglobin S negative and antigen-negative for any maternal antibody, if indicated. These RBC units should be concentrated to remove additives and increase the hematocrit thus minimizing fluctuations in fetal volume status. The units intended for IUT should be labeled clearly and the documentation of transfusion differentiated in the maternal medical record.

DISCUSSION

An awareness of the technical, logistical, and regulatory considerations for IUT performance will facilitate improved communication and patient care, especially when rare units of RBC are required.

Hemolytic disease of the fetus and newborn: rapid review of postnatal care and outcomes

BACKGROUND

Advances in postnatal care for hemolytic disease of the fetus and newborn (HDFN) have occurred over the past decades, but little is known regarding the frequency of postnatal treatment and the clinical outcomes of affected neonates. Most studies reporting on HDFN originate from high-income countries or relatively large centers, but important differences between centers and countries may exist due to differences in prevalence and available treatment options. We therefore aimed to evaluate the postnatal treatment landscape and clinical outcomes in neonates with Rhesus factor D (Rh(D))- and/or K-mediated HDFN and to provide recommendations for future research.

METHODS

We conducted a rapid literature review of case reports and series, observational retrospective and prospective cohort studies, and trials describing pregnancies or children affected by Rh(D)- or K-mediated HDFN published between 2005 and 2021. Information relevant to the treatment of HDFN and clinical outcomes was extracted. Medline, ClinicalTrials.gov and EMBASE were searched for relevant studies by two independent reviewers through title/abstract and full-text screening. Two independent reviewers extracted data and assessed methodological quality of included studies.

RESULTS

Forty-three studies reporting postnatal data were included. The median frequency of exchange transfusions was 6.0% [interquartile range (IQR): 0.0-20.0] in K-mediated HDFN and 26.5% [IQR: 18.0-42.9] in Rh(D)-mediated HDFN. The median use of simple red blood cell transfusions in K-mediated HDFN was 50.0% [IQR: 25.0-56.0] and 60.0% [IQR: 20.0-72.0] in Rh(D)-mediated HDFN. Large differences in transfusion rates were found between centers. Neonatal mortality amongst cases treated with intrauterine transfusion(s) was 1.2% [IQR: 0-4.4]. Guidelines and thresholds for exchange transfusions and simple RBC transfusions were reported in 50% of studies.

CONCLUSION

Most included studies were from middle- to high-income countries. No studies with a higher level of evidence from centers in low-income countries were available. We noted a shortage and inconsistency in the reporting of relevant data and provide recommendations for future reports. Although large variations between studies was found and information was often missing, analysis showed that the postnatal burden of HDFN, including need for neonatal interventions, remains high.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2021 CRD42021234940. Available from:  https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021234940 .

Nanopore Third-Generation Sequencing for Comprehensive Analysis of Hemoglobinopathy Variants

BACKGROUND

Oxford Nanopore Technology (ONT) third-generation sequencing (TGS) is a versatile genetic diagnostic platform. However, it is nonetheless challenging to prepare long-template libraries for long-read TGS, particularly the ONT method for analysis of hemoglobinopathy variants involving complex structures and occurring in GC-rich and/or homologous regions.

METHODS

A multiplex long PCR was designed to prepare library templates, including the whole-gene amplicons for HBA2/1, HBG2/1, HBD, and HBB, as well as the allelic amplicons for targeted deletions and special structural variations. Library construction was performed using long-PCR products, and sequencing was conducted on an Oxford Nanopore MinION instrument. Genotypes were identified based on integrative genomics viewer (IGV) plots.

RESULTS

This novel long-read TGS method distinguished all single nucleotide variants and structural variants within HBA2/1, HBG2/1, HBD, and HBB based on the whole-gene sequence reads. Targeted deletions and special structural variations were also identified according to the specific allelic reads. The result of 158 α-/β-thalassemia samples showed 100% concordance with previously known genotypes.

CONCLUSIONS

This ONT TGS method is high-throughput, which can be used for molecular screening and genetic diagnosis of hemoglobinopathies. The strategy of multiplex long PCR is an efficient strategy for library preparation, providing a practical reference for TGS assay development.