Fetal anaemia: diagnosis and management

Assessing Recommendations for Determining Fetal Risk in Alloimmunized Pregnancies in the United States: Is It Time to Update a Decades-Old Practice?

The current recommended testing algorithm for assessing the alloimmunized pregnancy utilized by many obstetricians in the United States (US) fails to consider the most recent evidence, placing fetuses, and mothers at unnecessary risk of poor outcome or death. This narrative review of the current landscape of fetal red blood cell (RBC) antigen testing evaluates the history of hemolytic disease of the fetus and newborn (HDFN) and how its discovery has continued to influence practices in the US today. We compare current US-based HDFN practice guidelines with those in Europe. We also provide transfusion medicine and hematology perspectives and recommendations addressing the limitations of US practice, particularly regarding paternal RBC antigen testing, and discuss the most valuable alternatives based on decades of data and evidence-based recommendations from Europe.

Abnormal heart rate pattern in fetal anaemia secondary to transient abnormal myelopoeisis in a fetus without trisomy 21: A case report

Decreased fetal movements (DFM) are a non-specific and common symptom in the third trimester of pregnancy that hold an association with fetal compromise. A 28-year-old woman at 31 weeks and 3 days of gestation presented with DFM and was found to have a pathological fetal heart rate trace. Following emergency Caesarean section the fetus was diagnosed with transient abnormal myelopoeisis (TAM). Timely treatment was initiated and the neonatal outcome was good. Transient myeloproliferative disorders are almost uniquely found in infants with trisomy 21 (T21). This is the first case report of TAM in the absence of T21 wherein the diagnostic process was commenced antenatally due to non-reassuring fetal status and highlights the importance of antenatal heart rate abnormalities.

Identification and management of congenital parvovirus B19 infection

Parvovirus B19 (B19V) infection is well known for its mild, self-limiting clinical presentations in children, such as erythema infectiosum. Approximately 40% of women of childbearing age are susceptible to B19V infection. While maternal B19V infection usually has a good prognosis, B19V can cause severe fetal anaemia and pregnancy loss due to its ability to suppress erythroid progenitor cells. Non-invasive ultrasound monitoring for fetal anaemia is usually performed if maternal seroconversion occurs in the first 20 weeks of gestation, with amniocentesis for fetal infection reserved for those who first present with fetal anaemia or hydrops of unknown cause. Intrauterine transfusion is the standard treatment for severe fetal anaemia and is associated with a significant improvement in survival. However, survivors of hydrops fetalis may have a higher rate of long-term neurodevelopmental complications compared with non-hydropic survivors. This review aims to synthesise published data on the diagnosis, surveillance and outcomes of congenital parvovirus infection to assist clinicians in diagnosing and managing this important condition.

The utility of MRI for measuring hematocrit in fetal anemia

BACKGROUND

Doppler ultrasound measurements of the peak systolic velocity of the middle cerebral artery can be used to noninvasively diagnose fetal anemia but are less precise following fetal blood transfusion and in late gestation. We have previously demonstrated the feasibility of estimating fetal hematocrit in vitro using magnetic resonance imaging relaxation times. Here we report the use of magnetic resonance imaging as a noninvasive tool to accurately detect fetal anemia in vivo.

OBJECTIVES

This study has 2 objectives: (1) to determine the feasibility and accuracy of magnetic resonance imaging in estimating hematocrit in anemic fetuses and (2) to compare magnetic resonance imaging and middle cerebral artery Doppler in detecting moderate to severe fetal anemia.

STUDY DESIGN

Fetuses undergoing fetal blood sampling or transfusion underwent magnetic resonance imaging examinations prior to and following their procedures at 1.5 Tesla (Siemens Avanto). A modified Look-Locker inversion pulse sequence and T₂ preparation sequence were applied for T₁ and T₂ mapping of the intrahepatic umbilical vein. Estimated fetal hematocrit was calculated using a combination of T₁ and T₂ values and compared with conventional hematocrit obtained from fetal blood samples and middle cerebral artery Doppler measurements.

RESULTS

Twenty-three fetuses were assessed during 33 magnetic resonance imaging scans. The mean absolute difference between the laboratory and magnetic resonance imaging-estimated hematocrit was 0.06 ± 0.05 with a correlation of 0.77 (P < .001) determined by a multilevel, mixed-effects model adjusting for the repeated measurements from the same participants, multiple gestation pregnancies, and the scan type (ie, before or after transfusion scan). Bland-Altman analysis revealed a systematic bias of -0.03 between the magnetic resonance imaging and fetal blood sampling measurements. Magnetic resonance imaging and middle cerebral artery Doppler had similar sensitivities of approximately 90% to detect moderate to severe anemia. However, magnetic resonance imaging had a higher specificity (93% [13/14], 95% confidence interval, 66-100%) than Doppler (71% [10/14], 95% confidence interval, 42-92%).

CONCLUSION

Moderate to severe fetal anemia can be detected noninvasively by magnetic resonance imaging with high sensitivity and specificity. Our results suggest an adjunct role for magnetic resonance imaging in fetuses with suspected anemia, particularly following previous transfusion and in late gestation.

Management of red blood cell alloimmunization in pregnancy

The main cause of fetal anemia is maternal red blood cell alloimmunization (AI). The search of maternal antibodies by indirect antiglobulin test allows screening for AI during pregnancy. In case of AI, fetal genotyping (for Rh-D, Rh-c, Rh-E and Kell), quantification (for anti-rhesus antibodies) and antibody titration, as well as ultrasound monitoring, are performed. This surveillance aims at screening for severe anemia before hydrops fetalis occurs. Management of severe anemia is based on intrauterine transfusion (IUT) or labor induction depending on gestational age. After intrauterine transfusion, follow-up will focus on detecting recurrence of anemia and detecting fetal brain injury. With IUT, survival of fetuses with alloimmunization is greater than 90% but 4.8% of children with at least one IUT have neurodevelopmental impairment.

Intrauterine Fetal Blood Transfusion: Descriptive study of the first four years' experience in Oman

OBJECTIVES

Haemolytic disease of the fetus and newborn (HDFN) causes hydrops fetalis. The successful treatment of HDFN has been reported with intrauterine blood transfusion (IUT). This study aimed to describe the initial experience with IUT procedures in Oman.

METHODS

This retrospective observational study took place at the Royal Hospital and Sultan Qaboos University Hospital Blood Bank, Muscat, Oman, and included all women who underwent IUT procedures in Oman between March 2012 and March 2016. Gestational and neonatal outcomes were assessed, including complications, morbidity, neurodevelopmental sequelae and mortality.

RESULTS

A total of 28 IUT procedures for 13 fetuses carried by 11 women were performed. Gestational age at the time of referral ranged from 13-30 weeks, while the median gestational age at first IUT procedure was 26 weeks (range: 19-30 weeks). Indications for the procedure included HDFN caused by anti-D (n = 6), a combination of anti-D and anti-C (n = 4), anti-K (n = 1) and anti-Jsb (n = 1) antibodies and nonimmune hydrops fetalis due to a congenital parvovirus infection (n = 1). Median fetal haemoglobin levels at the beginning and end of the procedure were 4.6 g/dL and 12.8 g/dL, respectively. Most procedures were transplacental intravascular transfusions through the placental umbilical cord root (71.4%), followed by transamniotic intravascular transfusions (14.3%). The overall survival rate was 61.5%, with five deaths; of these, four were intrauterine and one was an early neonatal death due to non-resolved hydrops and severe cardiac dysfunction.

CONCLUSION

As a relatively novel obstetric procedure in Oman, IUT seems to result in a favourable outcome for hydropic fetuses.

A pilot prospective study of fetomaternal hemorrhage identified by anemia in asymptomatic neonates

OBJECTIVE

Fetomaternal hemorrhage (FMH) is a poorly understood condition in which fetal erythrocytes transfer to the maternal circulation via a faulty placental barrier. Little is known about the true incidence, epidemiology or pathophysiology of FMH in the general pregnant population as existing studies are based on retrospective cohorts and manifest diagnosis and selection bias. The objective of this study was to evaluate the practicability of a prospective study of FMH in the general population based on antepartum maternal blood testing and neonatal anemia.

STUDY DESIGN

Prospective cohort study.

RESULT

Nineteen pregnant women were enrolled prior to the term delivery of 20 well infants. Five neonates were unexpectedly anemic on first postnatal testing. Antenatal maternal blood samples associated with two of the five anemic newborns had positive Kleihauer-Betke testing while no newborn with a normal postnatal blood count had an associated abnormal Kleihauer-Betke test.

CONCLUSION

Clinically significant FMH may be more common than previously thought. Prospective epidemiological study of FMH is feasible.

[Serious materno-fetal alloimmunization: about a case and review of the literature]

L'incompatibilité fœto-maternelle Rhésus peut être à l'origine d'un syndrome hémolytique dont l'expression clinique est l′anémie fœtale éventuellement compliquée par une anasarque fœto-placentaire ou à l'extrême une mort fœtale in utéro. Nous rapportons l'observation d'un cas d'allo immunisation Rhésus à 34 SA ayant aboutit un hydrops foetalis, l'extraction fœtale par césarienne en vue d'une exsanguino-transfusion a été réalisée, mais le nouveau né est décédé au cours de l'exsanguino-transfusion. Le dépistage des femmes à risque et l'utilisation d'Immunoglobulines anti D ont permis une réduction importante de l′incidence des accidents d'incompatibilité. La mesure du pic systolique de vélocité dans l'artère cérébrale moyenne a bouleversé la surveillance et la prise en charge prénatale des anémies fœtales secondaires à une allo-immunisation Rhésus. Son utilisation dans la surveillance des cas d'allo-immunisation Rhésus permettrait ainsi de réserver les procédures invasives (cordocentèse) comme geste thérapeutique qui permet la transfusion fœtale in utéro. Grâce à une collaboration multidisciplinaire cohérente, l'extraction fœtale peut être programmée, ce qui permet une prise en charge adéquate et rigoureuse, même des nouveaux nés avec atteinte sévère.

Harmless Pregnancy-Induced Warm Autoantibodies to Red Blood Cells

Background

There is little information concerning the development and significance of autoantibodies (aab) to red blood cells (RBCs) during pregnancy.

Methods

Unselected pregnant women were routinely screened for the presence of unexpected antibodies to RBCs using standard techniques.

Results

Between 2009 and 2013, 153,612 pregnant women were tested. The antibody screening test was positive in 1,721 women (1.12%). In 1,602 (1.04%) cases, immune and/or non-immune alloantibodies and cold-reactive aab were detected, whereas warm-reactive aab were found in 119 women (0.08%). In almost all cases, warm-reactive aab belonged to the IgG class. No evidence of the presence of significant haemolysis in affected women was observed.

Conclusion

Pregnant women may rarely develop aab to RBCs, which do not appear to cause haemolytic anaemia. Further clarification is required on the reasons behind the development of these aab and their clinical insignificance.

Parvovirus B19 Achievements and Challenges

Parvovirus B19 is a widespread human pathogenic virus, member of the Erythrovirus genus in the Parvoviridae family. Infection can be associated with an ample range of pathologies and clinical manifestations, whose characteristics and outcomes depend on the interplay between the pathogenetic potential of the virus, its adaptation to different cellular environments, and the physiological and immune status of the infected individuals. The scope of this review is the advances in knowledge on the biological characteristics of the virus and of virus-host relationships; in particular, the interactions of the virus with different cellular environments in terms of tropism and ability to achieve a productive replicative cycle, or, on the contrary, to establish persistence; the consequences of infection in terms of interference with the cell physiology; the process of recognition of the virus by the innate or adaptive immune system, hence the role of the immune system in controlling the infection or in the development of clinical manifestations. Linked to these issues is the continuous effort to develop better diagnostic algorithms and methods and the need for development of prophylactic and therapeutic options for B19V infections.

Demographics, clinical characteristics and outcomes of neonates diagnosed with fetomaternal haemorrhage

OBJECTIVE

To determine clinical characteristics, demographics and short-term outcomes of neonates diagnosed with fetomaternal haemorrhage (FMH).

DESIGN

The authors analysed the Nationwide Inpatient Sample, 1993 to 2008. Singleton births diagnosed with FMH were identified by International Classification of Diseases (ICD-9) code 762.3. Descriptive, univariate and multivariable regression analyses were performed to determine the national annual incidence of FMH over time as well as demographics and clinical characteristics of neonates with FMH.

RESULTS

FMH was identified in 12 116 singleton births. Newborns with FMH required high intensity of care: 26.3% received mechanical ventilation, 22.4% received blood product transfusion and 27.8% underwent central line placement. Preterm birth (OR 3.7), placental abruption (OR 9.8) and umbilical cord anomaly (OR 11.4) were risk factors for FMH. Higher patient income was associated with increased likelihood of FMH diagnosis (OR 1.2), and Whites were more likely to be diagnosed than ethnic minorities (OR 1.9). There was reduced frequency of diagnosis in the Southern USA (OR 0.8 vs the Northeastern USA).

CONCLUSIONS

Diagnosis of FMH is associated with significant morbidity as well as regional, socioeconomic and racial disparity. Further study is needed to distinguish between diagnostic coding bias and true epidemiology of the disease. This is the first report of socioeconomic and racial/ethnic disparities in FMH, which may represent disparities in detection that require national attention.

Brain ultrasound findings in neonates treated with intrauterine transfusion for fetal anaemia

BACKGROUND

The main causes of severe fetal anaemia are red-cell allo-immunization, parvo B19 virus infection and feto-maternal haemorrhage. Treatment consists of intrauterine transfusion (IUT). Neuro-imaging studies in surviving neonates treated with IUT are scarce.

AIMS

To assess if neonates treated with IUT for fetal anaemia are at risk for cerebral injury, report the incidence and severity of brain ultrasound (US) abnormalities and explore the relation between brain US findings and perinatal parameters and neurological outcome.

PATIENTS AND METHODS

Brain US scans of neonates born alive between 2001 and 2008 with at least one IUT were retrospectively reviewed and classified as normal, mildly or moderately/severely abnormal. Incidences of abnormalities were calculated for full-term and preterm neonates. Presence and severity of abnormalities were related to clinical and IUT related parameters and to neurological outcome around 2 years of age (adverse: moderate or severe disability; favourable: normal or mild disability).

RESULTS

A total of 127 neonates (82 born preterm) were included. Median number of IUTs was 3 (range 1-6) and of brain US 2 (1-6). Median gestational age and weight at birth were 36.6 (26.0-41.1) weeks and 2870 (1040-3950)g. In 72/127 (57%) neonates ≥1 abnormality was seen on brain US, classified as moderate/severe in 30/127 (24%). Neurological outcome was adverse in 5 infants. Presence of brain US abnormalities was not significantly related to any of the perinatal parameters or to neurological outcome.

CONCLUSIONS

Neonates undergoing IUT for fetal anaemia are at high risk of brain injury.

Predictive factors of perinatal mortality in transfused fetuses due to maternal alloimmunization: what really matters?

INTRODUCTION

Alloimmunization is the main cause of fetal anemia. There are not many consistent analyses associating antenatal parameters to perinatal mortality in transfused fetuses due to maternal alloimmunization. The study aimed to determine the prognostic variables related to perinatal death.

MATERIAL AND METHODS

A cohort study analyzed 128 fetuses treated with intrauterine transfusion (IUT), until the early neonatal period. Perinatal mortality was associated with prognostic conditions related to prematurity, severity of fetal anemia and IUT procedure by univariated logistic regression. Multiple logistic regression was used to compute the odds ratio (OR) for adjusting the hemoglobin deficit at the last IUT, gestational age at birth, complications of IUT, antenatal corticosteroid and hydrops.

RESULTS

Perinatal mortality rate found in this study was 18.1%. The hemoglobin deficit at the last IUT (OR: 1.26, 95% CI: 1.04-1.53), gestational age at birth (OR: 0.53, 95% CI: 0.38-0.74) and the presence of transfusional complications (OR: 5.43, 95% CI: 142-20.76) were significant in predicting fetal death.

CONCLUSION

Perinatal mortality prediction in transfused fetuses is not associated only to severity of anemia, but also to the risks of IUT and prematurity.

Medically indicated--iatrogenic prematurity

Premature delivery of an infant is occasionally performed because of complications of pregnancy. This article reviews common medical indications for preterm delivery and the available evidence supporting delivery before 37 weeks of gestation. In many conditions, few data exist to guide optimal timing of delivery and management is guided by expert opinion. Ultimately, an individual assessment must be made in each case to weigh the risks that pregnancy continuation poses to the mother and/or fetus with the risks of prematurity and its associated morbidities.

Parvovirus B19 infection in human pregnancy

Human parvovirus B19 infection is widespread. Approximately 30-50% of pregnant women are nonimmune, and vertical transmission is common following maternal infection in pregnancy. Fetal infection may be associated with a normal outcome, but fetal death may also occur without ultrasound evidence of infectious sequelae. B19 infection should be considered in any case of nonimmune hydrops. Diagnosis is mainly through serology and polymerase chain reaction. Surveillance requires sequential ultrasound and Doppler screening for signs of fetal anaemia, heart failure and hydrops. Immunoglobulins, antiviral and vaccination are not yet available, but intrauterine transfusion in selected cases can be life saving.

Determining the volume of blood required for the correction of foetal anaemia by intrauterine transfusion during pregnancies of Rh isoimmunised women

BACKGROUND

Severe anaemic foetuses of Rhesus (Rh) isoimmunised mothers are usually treated by intrauterine transfusion (IUT). It is helpful to determine the volume of blood necessary to raise the concentration of haemoglobin by 1.0 g/dL in response to intrauterine transfusions.

METHODS

In this cross-sectional, observational study we evaluated 107 first IUT for the correction of anaemia caused by haemolysis triggered by maternal Rh immunisation. The concentration of foetal haemoglobin was determined in umbilical cord blood before and after the IUT. The variation in foetal concentration of haemoglobin after transfusion was compared between groups of hydropic and non-hydropic foetuses, between groups of foetuses with different degrees of anaemia and with groups of gestational age less than or more than 28 weeks. The t-test for averages and ANOVA were used to compare average differences among the groups. p values less than 0.05 were considered statistically significant.

RESULTS

Fifty-five (61.4%) foetuses were found to be anaemic while hydrops was observed in 40 (44%) at the time of the IUT. The volume of red blood cell concentrate infused varied from 5 to 90 mL, with 11.2±1.5 mL being necessary to raise the circulating concentration of haemoglobin by 1.0 g/dL. The foetal response was not influenced significantly by either the degree of foetal anaemia (p=0.56) or the presence of hydrops (p=0.17). The foetuses with a gestational age of 28 weeks or less required a smaller volume of red blood cell concentrate than those with a gestational age of more than 28 weeks (9.3±5.4 mL and 13.4±4.8 mL, respectively; p<0.0001) in order to raise their concentration of circulating haemoglobin by 1.0 g/dL.

CONCLUSION

The volume of red blood cell concentrate necessary to correct anaemia in pregnancies complicated by Rh isoimmunisation must be considered carefully, since the response to the infusion of blood is peculiar in extremely premature infants. Hydrops and the degree of anaemia were not determinants of the change in the final concentration of circulating haemoglobin following the blood transfusion.

Assessment of the peak systolic velocity of the middle cerebral artery in twin-twin transfusion syndrome. Part I: preoperative assessment

OBJECTIVE

We sought to assess the incidence of an elevated peak systolic velocity of the middle cerebral artery (MCA-PSV) in twin-twin transfusion syndrome prior to laser surgery and its prognostic value for intrauterine fetal demise 24 hours after surgery (IUFD-24).

STUDY DESIGN

An elevated MCA-PSV was defined as a velocity > .5 multiples of the median by transabdominal pulsed Doppler. Gestational age, Quintero stage, and number and/or type of placental vascular anastomoses were assessed as risk factors for an elevated MCA-PSV. Risk of IUFD-24 was assessed relative to an elevated MCA-PSV.

RESULTS

An elevated MCA-PSV was present in 4.2% of donors, 3.2% of recipients (P = .5), and 1.5% of both twins in 189 patients with twin-twin transfusion syndrome. An elevated MCA-PSV was unrelated to gestational age, stage, and number or type of anastomoses. An elevated MCA-PSV in the recipient twin was associated with an increased risk of IUFD-24 of this fetus (P = .01).

CONCLUSIONS

An elevated MCA-PSV is present in < 5% of donor and recipient twins. An elevated MCA-PSV is a risk factor for IUFD-24 of the recipient twin.