Postponing Early intrauterine Transfusion with Intravenous immunoglobulin Treatment; the PETIT study on severe hemolytic disease of the fetus and newborn

Severity of haemolytic disease of the fetus and newborn in patients with a history of intrauterine transfusions in a previous pregnancy: A nationwide retrospective cohort study

OBJECTIVE

Pregnant women who received at least one intrauterine transfusion (IUT) for haemolytic disease of the fetus and newborn (HDFN) in the preceding pregnancy are presumed to have a high likelihood of requiring IUTs again, often starting at an earlier gestational age. Our aim was to quantify these risks in a large national cohort.

DESIGN

Retrospective cohort study of a nationwide Dutch database.

SETTING

The Netherlands.

POPULATION

All women treated in The Netherlands with IUTs for Rhesus D (RhD)- or Kell-mediated HDFN between 1999 and 2017 and their follow-up pregnancies were included. Pregnancies with an antigen-negative fetus were excluded.

METHODS

Electronic patient files were searched for the number and gestational age of each IUT, and analysed using descriptive statistics and linear regression.

MAIN OUTCOME MEASURES

Percentage of women requiring one or more IUTs again in the subsequent pregnancy, and gestational age at first IUT in both pregnancies.

RESULTS

Of the 321 women in our study population, 21% (69) had a subsequent ongoing pregnancy at risk. IUTs were administered in 86% (59/69) of cases. In subsequent pregnancies, the median gestational age at first IUT was 3 weeks earlier (interquartile range -6.8 to 0.4) than in the preceding pregnancy.

CONCLUSIONS

Our study shows that pregnant women with a history of IUTs in the previous pregnancy are highly likely to require IUTs again, and on average 3 weeks earlier. Clinicians need to be aware of these risks and ensure timely referral, and close surveillance from early pregnancy onwards. Additionally, for women with a history of IUT and their caregivers, this information is essential to enable adequate preconception counselling.

Intravenous immunoglobulin for the treatment of severe maternal alloimmunization: individual patient data meta-analysis

OBJECTIVE

This study aimed to investigate the outcomes associated with the administration of maternal intravenous immunoglobulin in high-risk red blood cell-alloimmunized pregnancies.

DATA SOURCES

Medline, Embase, and Cochrane Library were systematically searched until June 2023.

STUDY ELIGIBILITY CRITERIA

This review included studies reporting on pregnancies with severe red blood cell alloimmunization, defined as either a previous fetal or neonatal death or the need for intrauterine transfusion before 24 weeks of gestation in the previous pregnancy as a result of hemolytic disease of the fetus and newborn.

METHODS

Cases were pregnancies that received intravenous immunoglobulin, whereas controls did not. Individual patient data meta-analysis was performed using the Bayesian framework.

RESULTS

Individual patient data analysis included 8 studies consisting of 97 cases and 97 controls. Intravenous immunoglobulin was associated with prolonged delta gestational age at the first intrauterine transfusion (gestational age of current pregnancy - gestational age at previous pregnancy) (mean difference, 3.19 weeks; 95% credible interval, 1.28-5.05), prolonged gestational age at the first intrauterine transfusion (mean difference, 1.32 weeks; 95% credible interval, 0.08-2.50), reduced risk of fetal hydrops at the time of first intrauterine transfusion (incidence rate ratio, 0.19; 95% credible interval, 0.07-0.45), reduced risk of fetal demise (incidence rate ratio, 0.23; 95% credible interval, 0.10-0.47), higher chances of live birth at ≥28 weeks (incidence rate ratio, 1.88; 95% credible interval, 1.31-2.69;), higher chances of live birth at ≥32 weeks (incidence rate ratio, 1.93; 95% credible interval, 1.32-2.83), and higher chances of survival at birth (incidence rate ratio, 1.82; 95% credible interval, 1.30-2.61). There was no substantial difference in the number of intrauterine transfusions, hemoglobin level at birth, bilirubin level at birth, or survival at hospital discharge for live births.

CONCLUSION

Intravenous immunoglobulin treatment in pregnancies at risk of severe early hemolytic disease of the fetus and newborn seems to have a clinically relevant beneficial effect on the course and severity of the disease.

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.

Clinical response to therapeutic plasmapheresis and intravenous immunoglobulin in pregnancies complicated by alloimmunization despite persistently high titers: Report of two cases

Key Clinical Message

Plasmapheresis and IVIG use in cases of alloimmunization during pregnancy are effective strategies when severe early fetal anemia is anticipated. Despite no change in antibody titer levels before and after plasmapheresis, clinical response was observed in both fetuses, and both had an excellent obstetrical outcome.

Abstract

Hemolytic disease of the fetus and newborn is a potentially lethal complication of alloimmunization, and intrauterine fetal blood transfusion (IUBT) is the standard treatment and care plan for severe fetal anemia. However, IUBT is technically unattainable before 20 weeks of gestation. Plasmapheresis and intravenous immunoglobulin (IVIG) are the two treatment modalities described in the literature that postpone the need for transfusion until after 20 weeks. Here, we present two cases of alloimmunization (one with anti-Kell and the other with anti-D). Both had poor outcomes in previous pregnancies because of the early development of severe fetal anemia and hydrops before 24 weeks of gestation. Both patients underwent three sessions of plasmapheresis before 18 weeks, followed by weekly IVIG infusion, which continued until 23-27 weeks of pregnancy. Antibody titers were measured before and after plasmapheresis. In addition, weekly MCA Doppler was performed to monitor the development of severe fetal anemia requiring blood transfusion, which was diagnosed when the peak systolic velocity (PSV) was 1.5 multiples of the median or more. The first patient underwent IUBT at 24 weeks and the second at 28 weeks, as indicated by the MCA Doppler. Both patients were delivered by cesarean section, the first at 34 weeks and the second at 36 weeks, for different obstetrical indications. Both pregnancies resulted in a live birth. We conclude that the use of plasmapheresis and IVIG in alloimmunization during pregnancy is an effective treatment strategy when severe early fetal anemia is anticipated before 20 weeks of gestation. Despite no change in antibody titer levels before and after plasmapheresis, a clinical response was observed in both fetuses, and both had excellent obstetrical outcomes.

Effective management of foetal anaemia in Rh(D) alloimmunised pregnant women with intrauterine transfusion: a Systematic Review

BACKGROUND

Foetal anaemia is caused by a severe pregnancy complication, haemolytic disease of the foetus and newborn. Intrauterine transfusions (IUTs) are performed to treat foetal anaemia in alloimmunised pregnant women. If left untreated hydrops can develop thereby reducing the chance of survival. Survival rates have improved but the procedure is not without complications. Procedure-related complications can be associated with early gestational age, hence delaying IUT could improve outcomes. This review aims to determine the effectiveness and safety of IUTs by examining survival and mortality rates, procedure-related complications with associated foetal mortality and the influence of hydrops.

STUDY DESIGN AND METHOD

A systematic review was conducted by searching keywords in four scientific databases from January 2000 to April 2022. A meta-analysis was performed with the OpenMeta-Analyst software using an arcsine transformed proportion with the binary random-effects model and maximum likelihood method.

RESULTS

Fifteen studies were identified as eligible and used in the meta-analysis. The forest plots all showed statistically significant outcomes with heterogeneity of data. Results indicated a greater foetal survival rate with IUT to treat anaemic foetuses, a low foetal mortality rate, and low risk of procedure-related complications associated with foetal loss but a higher risk of foetal mortality when hydrops is present.

CONCLUSION

The findings of this systematic review and meta-analysis provide evidence that IUT is a safe and effective treatment for foetal anaemia in the absence of hydrops when experienced personnel perform the procedure to minimise the risk of procedure-related complications.

Intravenous immunoglobulin treatment of congenital parvovirus B19 induced anemia - a case report

BACKGROUND

Parvovirus is a common childhood infection that could be very dangerous to the fetus, if pregnant women become infected. The spectrum of effects range from pure red blood cell aplasia with hydrops fetalis to meningoencephalitis, with many symptoms in between. Severe anemia in the setting of pure red blood cell aplasia is one of the more common effects that neonatal experience (if infected intrapartum), with the current gold standard treatment being intrauterine or postnatal packed red blood cell (PRBC) transfusions, yet intravenous immunoglobulin (IVIG) may be a superior treatment option.

CASE PRESENTATION

A preterm infant was born at 26th week of gestational age via emergency Cesarean section due to hydrops fetalis, with parvovirus B19 exposure one month prior. The infant tested positive for IgM antibodies against parvovirus B19. Among many other serious complications of both hydrops fetalis and premature delivery, the infant had severe unremitting anemia, and received many PRBC transfusion over the course of his 71-day-long neonatal intensive care unit stay. During a follow up appointments as outpatient, his blood tests showed persistent high copies of parvovirus B19. He was then supported with PRBC transfusions and treated with IVIG. After three doses of IVIG, the infant's parvovirus B19 viral copy numbers have dramatically reduced and the infant did not require any more PRBC transfusions.

CONCLUSIONS

IVIG infusion effectively treated the parvovirus B19 infection and restored erythropoiesis making the child transfusion independent. Furthermore, since IVIG is safe and readily crosses the placenta, further studies are needed to determine if IVIG should be considered as an alternative prenatal treatment for congenital parvovirus B19 infection.

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

BACKGROUND

Prevention of pregnancy-related alloimmunization and the management of hemolytic disease of the fetus and newborn (HDFN) has significantly improved over the past decades. Considering improvements in HDFN care, the objectives of this systematic literature review were to assess the prenatal treatment landscape and outcomes of Rh(D)- and K-mediated HDFN in mothers and fetuses, to identify the burden of disease, to identify evidence gaps in the literature, and to provide recommendations for future research.

METHODS

We performed a systematic search on MEDLINE, EMBASE and clinicaltrials.gov. Observational studies, trials, modelling studies, systematic reviews of cohort studies, and case reports and series of women and/or their fetus with HDFN caused by Rhesus (Rh)D or Kell alloimmunization. Extracted data included prevalence; treatment patterns; clinical outcomes; treatment efficacy; and mortality.

RESULTS

We identified 2,541 articles. After excluding 2,482 articles and adding 1 article from screening systematic reviews, 60 articles were selected. Most abstracted data were from case reports and case series. Prevalence was 0.047% and 0.006% for Rh(D)- and K-mediated HDFN, respectively. Most commonly reported antenatal treatment was intrauterine transfusion (IUT; median frequency [interquartile range]: 13.0% [7.2-66.0]). Average gestational age at first IUT ranged between 25 and 27 weeks. weeks. This timing is early and carries risks, which were observed in outcomes associated with IUTs. The rate of hydrops fetalis among pregnancies with Rh(D)-mediated HDFN treated with IUT was 14.8% (range, 0-50%) and 39.2% in K-mediated HDFN. Overall mean ± SD fetal mortality rate that was found to be 19.8%±29.4% across 19 studies. Mean gestational age at birth ranged between 34 and 36 weeks.

CONCLUSION

These findings corroborate the rareness of HDFN and frequently needed intrauterine transfusion with inherent risks, and most births occur at a late preterm gestational age. We identified several evidence gaps providing opportunities for future studies.

Intravenous immunoglobulin in the management of severe early onset red blood cell alloimmunisation

Our objective was to assess the effect of maternal intravenous immunoglobulin (IVIG) administration for severe red blood cell (RBC) alloimmunisation on fetal outcomes. This is a case-control study. Women with a history of severe early onset alloimmunisation resulting in fetal loss in a previous pregnancy and high anti-D or anti-K antibody titres received IVIG in a subsequent pregnancy. We assessed gestational age at first transfusion and fetal outcomes in the subsequent pregnancy and compared these with the outcomes in the previous pregnancy. The most responsible antibody was anti-D in 17 women and anti-K in two others, whilst seven had more than one antibody. In all, 19 women received IVIG in 22 pregnancies, two of which did not even need an intrauterine transfusion (IUT). For previous early losses despite transfusion, IVIG was associated with a relative increase in fetal haemoglobin between treated and untreated pregnancies of 36.5 g/L (95% confidence interval 19.8-53.2, p = 0.0013) and improved perinatal survival (eight of eight vs. none of six, p = 0.001). For previous losses at <20 weeks, it enabled first transfusion deferral in subsequent pregnancies to at least 19.9 weeks (mean 23.2 weeks). Overall, IVIG decreases the severity of haemolytic disease of the fetus and newborn and allows deferral of the first IUT to a safer gestation in severe early-onset RBC alloimmunisation and rarely may even avoid the need for IUT entirely.

Case report: Double filtration plasmapheresis (DFPP) for severe rhesus-D alloimmunization in two pregnant patients

Maternal erythrocyte alloimmunization is one of the most important causes of fetal anemia. The standard treatment for anemic fetuses is intrauterine blood transfusion (IUT). However, IUT may have adverse effects, particularly before 20 weeks of gestation. In this report, two women who had previously had severely affected alloimmunized pregnancy developed high titers of anti-D antibodies before 20 weeks of gestation. Ultrasound Doppler showed severe fetal anemia, and intrauterine transfusion was expected to be unavoidable. To prolong pregnancy to a gestation in which intravascular IUT was possible, we used repeated double filtration plasmapheresis (DFPP) as a rescue therapy. The titers of IgG-D, IgG-A, and IgG-B decreased after DFPP treatment. One woman successfully prolonged pregnancy until 20 weeks of gestation. Subsequently, she underwent four cycles of IUTs and delivered at 30 weeks of gestation by emergency cesarean section due to fetal bradycardia during the fifth intrauterine transfusion. The other woman successfully delayed intrauterine transfusion until 26 weeks of gestation. The favorable results of the two patients indicate that DFPP may be an effective and safe treatment modality for RhD immunity in pregnant women. Moreover, DFPP is potentially helpful for reducing the occurrence of ABO hemolytic disease in neonates due to the clearance of IgG-A and IgG-B antibodies (e.g., O pregnant women harbored A/B/AB neonates). However, more clinical trials are needed to verify the results.

Immunomodulation for early-onset haemolytic disease of the fetus/newborn: Can we delay the need for intrauterine transfusions?

When cases of severe fetal anaemia due to maternal red-cell alloimmunization present in the early second trimester, standard treatment with intrauterine transfusion often results in fetal loss. The report by Vlachodimitropoulou et al. offers new insight into the use of maternal intravenous immune globulin to delay the need for intrauterine transfusion. Performing these procedures at a later gestational age increases the likelihood of technical success and subsequent perinatal survival. Commentary on: Vlachodimitropoulou et al. Intravenous immune globulin in the management of severe early onset of red cell alloimmunization. Br J Haematol 2023; 200:97-103.

Identification and management of fetal anemia due to hemolytic disease

INTRODUCTION

Hemolytic disease of the fetus and newborn (HDFN) is a condition caused by maternal alloantibodies against fetal red blood cells (RBCs) that can cause severe morbidity and mortality in the fetus and newborn. Adequate screening programs allow for timely prevention and intervention resulting in significant reduction of the disease over the last decades. Nevertheless, HDFN still occurs and with current treatment having reached an optimum, focus shifts toward noninvasive therapy options.

AREAS COVERED

This review focusses on the timely identification of high risk cases and antenatal management. Furthermore, we elaborate on future perspectives including improvement of screening, identification of high risk cases and promising treatment options.

EXPERT OPINION

In high-income countries mortality and morbidity rates due to HDFN have drastically been reduced over the last decades, yet worldwide anti-D mediated HDFN still accounts for 160,000 perinatal deaths and 100,000 patients with disabilities every year. Much of these deaths and disabilities could have been avoided with proper identification and prophylaxis. By implementing sustainable prevention, screening, and disease treatment measures in all countries this will systemically reduce unnecessary perinatal deaths. There is a common responsibility to engage in this cause.

Effect of intravenous immunoglobulins to postpone the gestational age of first intrauterine transfusion in very severe red blood cell alloimmunization: A case-control study

BACKGROUND

Early intrauterine transfusion (IUT) is associated with a higher risk of fetal loss. Our objective was to evaluate the efficiciency of intravenous immunoglobulins (IVIG) to postpone the gestational age at first IUT beyond 20 weeks of gestation (WG) compared to the previous pregnancy in case of very severe red blood cell (RBC) alloimmunization.

STUDY DESIGN AND METHODS

Very severe RBC alloimmunization was defined by a high titer of antibodies and a previous pregnancy complicated by a first IUT before 24 WG and/or perinatal death directly related to alloimmunization. We performed a single-center case-control study. Cases and controls were patients respectively treated with weekly IVIG infusions started before 13 WG, and without.

RESULTS

Twenty cases and 21 controls were included. Gestational age (GA) at first IUT was postponed after 20 WG in 18/20 (90 %) of patients treated with IVIG and in 15/21 (71 %) in the control group (p = 0.24). Compared to the previous pregnancy, the GA at first IUT was postponed by a median of 22 [+11; +49] days in the IVIG group and occurred in average 2 days earlier [-17 ; +12] in the non-treated group (p = 0.02). There was no difference between number of IUT and need for exchange-transfusion. IVIG treatment was associated with a significant decrease of antibodies' quantitation.

CONCLUSION

In our series, IVIG tends to differ first IUT beyond 20 WG and have a significant effect in postponing the gestational age of the first IUT in patients with very severe RBC alloimmunization.

Rh Alloimmunisation: Current Updates in Antenatal and Postnatal Management

In spite of advances in medical science, Rh alloimmunisation remains one of the leading causes of preventable neuro-morbidities and significant neonatal hyperbilirubinemia in lower-middle income countries. Despite availability of effective antenatal preventive strategy (Anti-D), its uptake in antenatal period is low due to ignorance. Further, once diagnosed, there is lack of adequate antenatal follow up in health care facility. Some of these cases even remain undiagnosed in antenatal period only to present as a case of severe hyperbilirubinemia and kernicterus in late neonatal period. Thus, there is an urgent need for creating awareness and educating health care professionals for early detection and timely management in both antenatal and postnatal period. Following two doses of anti-D prophylaxis (one in antenatal period and one in immediate postnatal period) the incidence of Rh alloimmunisation can reduce to <1%. It is recommended to follow all Rh alloimmunised pregnancies antenatally with serial indirect Coombs test titre (till critical titre is reached) followed by serial Doppler velocimetry of middle cerebral artery in a perinatal centre where facility for intrauterine transfusion as well as advanced neonatal care is available. Postnatal management of these infants comprises of confirmation of diagnosis, aggressive phototherapy and in selective cases, double volume exchange transfusion. With appropriate antenatal and postnatal management, the prognosis of Rh alloimmunised pregnancy remains favourable and long term outcome of Rh alloimmunised infants remain comparable with their normal counterparts.

The rhesus incompatible pregnancy and its consequences for affected fetuses and neonates

Rhesus incompatibility in pregnancy may result in haemolytic disease of the fetus and newborn (HDFN). This review discusses the fetal, neonatal and long-term consequences of HDFN and its management. Untreated, the fetal and neonatal prognosis of HDFN is poor. Provision of intravascular intrauterine transfusion (IUT) in a dedicated referral centre significantly reduces perinatal loss. Early-onset, severe fetal anaemia carries a greater risk of adverse fetal and neonatal outcomes and is less amenable to treatment with IUT. Interventions to prevent and treat severe, early onset disease have been investigated, however evidence from randomised controlled trials is required. Neonatal consequences of Rhesus haemolytic disease include early and late postnatal anaemia, and hyperbilirubinaemia leading to bilirubin-induced neurological dysfunction. Neurodevelopmental impairment and adult cardiovascular disease are long-term complications that have been reported in association with severe fetal anaemia. Strategies to prevent fetal hydrops, and further research into the long-term impacts of fetal anaemia may improve health outcomes for adult survivors of HDFN.

Medical therapy to attenuate fetal anaemia in severe maternal red cell alloimmunisation

Haemolytic disease of the fetus and newborn (HDFN) remains an important cause of fetal mortality with potential neonatal and longer-term morbidity. HDFN is caused by maternal red cell alloimmunisation, with IgG antibodies crossing the placenta to destroy fetal erythroid cells expressing the involved antigen. Intrauterine fetal blood transfusion is the therapy of choice for severe fetal anaemia. Despite a strong evidence base and technical advances, invasive fetal therapy carries risk of miscarriage and preterm birth. Procedure-related risks are increased when invasive, in utero transfusion is instituted prior to 22 weeks to treat severe early-onset fetal anaemia. This review focuses upon this cohort of HDFN and discusses intravenous immunoglobin (IVIg) and novel monoclonal antibody (M281, nipocalimab) treatments which, if started at the end of the first trimester, may attenuate the transplacental passage and fetal effects of IgG antibodies. Such therapy has the ability to improve fetal survival in this severe presentation of HDFN when early in utero transfusion may be required and may have wider implications for the perinatal management in general.

Red cell alloimmunization: A 2020 update

Management of maternal red cell alloimmunization has been revolutionized over the last 60 years. Advances in the prevention, screening, diagnosis, and treatment of alloimmune-induced fetal anemia make this condition an exemplar for contemporary practice in fetal therapy. Since survival is now an expectation, attention has turned to optimization of long-term outcomes following an alloimmunized pregnancy. In this review, the current management of red cell alloimmunization is described. Current research and future directions are discussed with particular emphasis on later life outcomes after alloimmune fetal anemia.

Plasmapheresis for the Treatment of Anti-M Alloimmunization in Pregnancy

Intrauterine transfusion is the standard antenatal treatment for a fetus with severe anemia. Plasmapheresis is an alternative treatment for cases with a history of severe hemolytic disease of the fetus and newborns at less than 20 weeks of gestation. There is only one previous report of plasmapheresis for the anti-M alloimmunization in pregnancy, and we report here on the successful treatment of plasmapheresis for anti-M alloimmunization. A woman with a history of intrauterine fetal death at 24 weeks of gestation due to severe fetal anemia caused by anti-M alloimmunization received plasmapheresis once or twice a week from 14 weeks of gestation onward. An intrauterine blood transfusion was conducted at 28 weeks, and a cesarean section was performed at 31 weeks. The infant had anemia and jaundice but was discharged at day 46. Plasmapheresis may delay the development of fetal anemia and reduce the risk of early and repeat intrauterine transfusion in cases of anti-M alloimmunization in pregnancy.

Necrotizing enterocolitis in haemolytic disease of the newborn: a retrospective cohort study

BACKGROUND AND OBJECTIVES

Necrotizing enterocolitis (NEC) is a common and often severe gastrointestinal emergency in newborn infants. While usually affecting (very) premature infants, an association between NEC and haemolytic disease of the foetus and newborn (HDFN) has been suggested. HDFN may be an additional risk factor to develop NEC. The objective of this study was to evaluate the occurrence of NEC in infants affected with moderate to severe HDFN in a large single centre cohort as compared to a broad population of infants without HDFN.

MATERIALS AND METHODS

Retrospective cohort study of medical records of neonates with and without HDFN, with a gestational age at birth ≥30 weeks and ≤38 weeks, and admitted to the Leiden University Medical Center between January 2000 and December 2016.

RESULTS

A total of 3284 patient records of infants born in the study period were reviewed and 317 cases of HDFN were identified. The incidence of NEC was significantly higher among infants with HDFN compared to infants without HDFN: 4/317 affected infants (1·3%) vs. 11/2967 affected infants (0·4%, relative risk 3·40, 95% confidence interval: 1·09-10·63).

CONCLUSIONS

We observed a higher incidence of NEC in an overall late preterm to near term population of infants with moderate to severe HDFN, compared to infants born without HDFN. The clinician taking care of an HDFN-affected infant should be cautious of this higher risk.

Introduction of Noninvasive Prenatal Testing for Blood Group and Platelet Antigens from Cell-Free Plasma DNA Using Digital PCR

Background

Noninvasive prenatal testing (NIPT) for fetal antigens is a common standard for targeted immune prophylaxis in RhD-mediated hemolytic disease of the fetus and newborn, and is most frequently done by quantitative PCR (qPCR). A similar approach is considered for other blood group and human platelet alloantigens (HPA). Because of a higher sensitivity compared to qPCR for rare molecule detection, we established and validated digital PCR (dPCR) assays for the detection of RHD exons 3, 5 and 7, KEL1, HPA-1a, and HPA-5b from cell-free DNA (cfDNA) in plasma. The dPCR assays for the Y-chromosomal marker amelogenin and autosomal SNPs were implemented as controls for the proof of fetal DNA.

Methods

Validation was performed on dilution series of mixed plasma samples from volunteer donors with known genotypes. After preamplification of the target loci, two-color (FAM and VIC) TaqMan^TM probe chemistry and chip-based dPCR were applied. The assays for RHD included GAPDH as an internal control. For the diallelic markers KEL1/2, HPA-1a/b, HPA-5a/b, and AMEL-X/Y and 3 autosomal SNPs, the probes enabled allelic discrimination in the two fluorescence channels. The dPCR protocol for NIPT was applied to plasma samples from pregnant women.

Results

The RHD exon 5 assay allowed the detection of a 0.05% RHD target in an RhD-negative background, whereas the exon 7 assay required at least a 0.25% target. The exon 3 assay showed the highest background and required at least a 2.5% RHD target for reliable detection. The dPCR assays for the diallelic markers revealed similar sensitivity and enabled the detection of at least a 0.5% target allele. The HPA-1a assay was the most sensitive and allowed target detection in plasma mixtures containing only 0.05% HPA-1a. The plasma samples from 13 pregnant women at different gestational ages showed unambiguous positive and negative results for the analyzed targets.

Conclusion

Analysis of cfDNA from maternal plasma using dPCR is suitable for the detection of fetal alleles. Because of the high sensitivity of the assays, the NIPT protocol for RhD, KEL1, and HPA can also be applied to earlier stages of pregnancy.

The Outcome of Hemolytic Disease of the Fetus and Newborn Caused by Anti-Rh17 Antibody: Analysis of Three Cases and Review of the Literature

Background

Anti-Rh17 is a rare red blood cell (RBC) antibody to high-frequency antigens that may cause severe hemolytic disease of the fetus and newborn (HDFN). Despite the rarity of HDFN caused by Anti-Rh17, this antibody was reported in many different populations. Emergency transfusions, especially exchange transfusions, present a huge problem if no compatible RBCs of phenotype D- are available.

Methods

Here we report obstetrical histories of three women and describe their pregnancies complicated by anti-Rh17 antibodies. We summarized published cases of pregnancies complicated by anti-Rh17 and reviewed transfusion treatment and outcomes. Additionally, a simplified flowchart for the management of such pregnancies is proposed.

Results

Four pregnancies were affected by severe HDFN, and three of them ended with perinatal death. In the fourth case, the baby was born hydropic and icteric and the condition was rapidly deteriorating. Emergency exchange transfusion was performed with incompatible O-negative RBC units in AB-negative plasma. The baby was discharged on the 14th day in good health. In the available literature, 15 women and 22 pregnancies were reported, 20 of them developed severe HDFN. According to the data, intrauterine transfusion for treatment of HDFN was the most common form of treatment with the donation of the mother's blood. Different options for exchange transfusion were described, including incompatible RBCs.

Conclusion

In more than 90% of described pregnancies of HDFN caused by anti-Rh17 antibody, transfusion treatment was required. Therefore, RBC from D- phenotype has to be available. According to published data, in emergent circumstances when maternal and blood from donor with phenotype D- is not available, incompatible exchange transfusion is a better choice than delaying transfusion when it is necessary. It is of essential importance that pregnancies with high risk of HDFN due to anti-Rh17 are managed by a multidisciplinary team (transfusion medicine specialist, obstetrician, neonatologist) in a highly specialized tertiary institution.

Fetal anemia: Diagnosis and management

Fetal anemia has been known for many years as a dangerous complication of pregnancy. Its most common causes are maternal alloimmunization and parvovirus B19 infection, although it can be associated with many different pathological conditions including fetal aneuploidies, vascular tumors, and arteriovenous malformations of the fetus or placenta and inherited conditions such as alpha-thalassemia or genetic metabolic disorders. Doppler ultrasonographic assessment of the peak velocity of systolic blood flow in the middle cerebral artery for the diagnosis of fetal anemia and intravascular intrauterine transfusion for its treatment are the current practice standards. Live birth rates as high as 95% have been reported in recent years. The additional role of intravenous immunoglobulin therapy and the long-term consequences of the condition are the subjects of active ongoing research.

Fetal anemia

The diagnosis and management of fetal anemia has been at the forefront of advances in the fields of fetal physiology, immunology, fetal imaging, and fetal therapy among others. Alloimmunization and parvovirus infection are the leading cause of fetal anemia in the United States. The middle cerebral artery peak systolic velocity (MCA-PSV) diagnoses fetal anemia. Its discovery is considered one of the most important achievements in fetal medicine. Accumulation of experience in recent years as well as refinement of surgical techniques have led to safer invasive procedures. It is expected that long term follow-up of affected pregnancies, continues to reflect all these improvements in care. It is also expected that treatment of other less common causes of fetal anemia becomes more frequently reported and that the management principles of fetal anemia are successfully applied to other fetal pathologies.