Risk factors for RhD immunisation despite antenatal and postnatal anti-D prophylaxis

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.

Magnitude of Red Blood Cell Alloimmunization Among Pregnant Women Attending Antenatal Care at Wolaita Sodo University Comprehensive Specialized Hospital, Southwest Ethiopia

Background

Maternal red cell alloimmunization occurs when a woman's immune system becomes sensitive to unfamiliar red blood cell antigens. This leads to the production of alloantibodies, which can have serious implications for the fetus and newborn. However, there is a lack of comprehensive information about the extent of red cell alloimmunization in underdeveloped countries like Ethiopia. Therefore, this study aimed to determine the magnitude of red cell alloimmunization among pregnant women attending antenatal care at Wolaita Sodo University Comprehensive Specialized Hospital from September 01 to November 30, 2022.

Methods

In this institutional-based cross-sectional study, 422 pregnant women were participated and recruited using a systematic random sampling technique. Data on sociodemographic characteristics, obstetric history, and other clinical information were collected using structured questionnaires through face-to-face interview. Blood grouping and indirect antihuman globulin tests were performed. The relationship between red cell alloimmunization and the independent variables was determined using the chi-square test. P-value <0.05 was considered statistical significance.

Results

In this study, the blood group distributions among the participants were as follows: O, 177 (41.9%); A, 124 (29.4%); B, 76 (18%); and AB, 45 (3.86%). Among the pregnant women included in the study, a total of 51 (12.08%) were identified as RhD-negative. Out of these RhD-negative women, 5 (9.8%) were found to have developed alloimmunization with red blood cell antigens. Miscarriage and post-partum hemorrhage were found to be important factors associated with the occurrence of red cell alloimmunization in these women.

Conclusion

This study showed that one out of ten pregnant women was alloimmunized. Therefore, antenatal blood grouping and indirect antihuman globulin screening should be performed routinely to manage and minimize the undesirable outcomes of alloimmunization during pregnancy.

Red cell alloimmunization in pregnancy: a study from a premier tertiary care centre of Western India

OBJECTIVE

The study was conducted to determine the frequency of alloimmunization to various blood group antibodies in pregnant women, and the risk of hemolytic disease in the fetus and newborn.

METHODS

All antenatal women, irrespective of the period of gestation or obstetric history, were included, whereas those taking anti-D immune-prophylaxis or with a history of blood transfusion were excluded. Antibody screening and identification were performed using a Bio-Rad ID microtyping system.

RESULTS

Of 2,084 antenatal females, 1,765 were D-antigen positive and 319 D-antigen negative. Sixty-five (3.119%) women alloimmunized. Out of 54 (2.591%) who had sensitized to D-antigen, 11 (0.527%) also sensitized to other antibodies. These 11 alloantibodies identified included: anti-M (n=6; 9.23%), anti-C (n=1; 3.076%), anti-E (n=1; 1.538%), anti-e (n=1; 1.538%), anti-Lewis (a) (n=1; 1.538%), and unspecified antibodies (n=1; 1.538%). Multiple antibodies were seen in four patients that combined: anti-D and anti-C (n=2; 3.076%), anti-e and anti-c (n=1; 1.538%), and anti-D and anti-G (n=1; 1.538%).

CONCLUSION

The rate of alloimmunization in D-antigen-negative women was high. Apart from this, the alloimmunization rate in women with bad obstetric history was very high, at 8.1%. In developing countries such as India, universal antenatal antibody screening, though desirable, may not be justified at present, as the cost and infrastructure required would be immense because of the lower alloimmunization rates in RhD antigen-positive women. However, it is necessary to impose properly formulated protocols to screen pregnant women with bad obstetric history.

Following targeted routine antenatal anti-D prophylaxis, almost half of the pregnant women had undetectable anti-D prophylaxis at delivery

INTRODUCTION

In September 2016, a nationwide targeted routine antenatal anti-D prophylaxis program was implemented in Norway. The prophylaxis (anti-D immunoglobulin) aims to cover the whole third trimester and is administered in gestational week 28 to RhD-negative women who carry RhD-positive fetuses. However, in many women, antibody screening at delivery does not detect anti-D immunoglobulin. The goal of this study was to investigate the presumable role of dose and timing of antenatal anti-D immunoglobulin administration in non-detectable prophylaxis at the time of delivery.

MATERIAL AND METHODS

In this retrospective observational study, RhD-negative pregnant women who gave birth at Oslo University Hospital and Akershus University Hospital between January 2017 and December 2019 were analyzed. Women who received antenatal anti-D immunoglobulin (1500 IU at Oslo University Hospital and 1250 IU at Akershus University Hospital) when fetal RHD genotyping at gestational week 24 predicted an RhD-positive fetus were included if an antibody screen at delivery was available. Data from the blood bank, maternity information systems, and electronic patient records were used.

RESULTS

Analysis of the 984 RhD-negative women at the two hospitals revealed that 45.4% had non-detectable anti-D at delivery. A significant difference between the two hospitals was observed: 40.5% at Oslo University Hospital (n = 509) and 50.7% at Akershus University Hospital (n = 475) (p = 0.001). The proportion with non-detectable anti-D increased to 56.0 and 75.3%, respectively (p = 0.008) in the group of women who gave birth 12 weeks after routine antenatal anti-D prophylaxis. Significantly fewer women had detectable anti-D at delivery when the lower anti-D immunoglobulin dose (1250 IU) was administered antenatally. Multiple logistic regression indicated that the time interval between routine antenatal anti-D prophylaxis and delivery, in addition to anti-D dose, were significantly associated with detectable anti-D at delivery (p < 0.001).

CONCLUSIONS

We do not know which RhD-negative pregnant women, despite antenatal anti-D prophylaxis, are at risk of RhD alloimmunization, when antibody screening is negative at delivery. Administration of antenatal prophylaxis should probably be moved closer to delivery, since the risk of fetomaternal hemorrhage is higher during the last weeks of the third trimester.

Risk factors for RhD immunisation in a high coverage prevention programme of antenatal and postnatal RhIg: a nationwide cohort study

OBJECTIVE

To evaluate which risk factors for RhD immunisation remain, despite adequate routine antenatal and postnatal RhIg prophylaxis (1000 IU RhIg) and additional administration of RhIg. The second objective was assessment of the current prevalence of RhD immunisations.

DESIGN

Prospective cohort study.

SETTING

The Netherlands.

POPULATION

Two-year nationwide cohort of alloimmunised RhD-negative women.

METHODS

RhD-negative women in their first RhD immunised pregnancy were included for risk factor analysis. We compared risk factors for RhD immunisation, occurring either in the previous non-immunised pregnancy or in the index pregnancy, with national population data derived from the Dutch perinatal registration (Perined).

RESULTS

In the 2-year cohort, data from 193 women were eligible for analysis. Significant risk factors in women previously experiencing a pregnancy of an RhD-positive child (n = 113) were: caesarean section (CS) (OR 1.7, 95% CI 1.1-2.6), perinatal death (OR 3.5, 95% CI 1.1-10.9), gestational age >42 weeks (OR 6.1, 95% CI 2.2-16.6), postnatal bleeding (>1000 ml) (OR 2.0, 95% CI 1.1-3.6), manual removal of the placenta (MRP) (OR 4.3, 95% CI 2.0-9.3); these factors often occurred in combination. The miscarriage rate was significantly higher than in the Dutch population (35% versus 12.-5%, P < 0.001).

CONCLUSION

Complicated deliveries, including cases of major bleeding and surgical interventions (CS, MRP), must be recognised as a risk factor, requiring estimation of fetomaternal haemorrhage volume and adjustment of RhIg dosing. The higher miscarriage rate suggests that existing RhIg protocols need adjustment or better compliance.

Time points and risk factors for RhD immunizations after the implementation of targeted routine antenatal anti-D prophylaxis: A retrospective nationwide cohort study

INTRODUCTION

Targeted routine antenatal anti-D prophylaxis was introduced to the national prophylaxis program in Finland in late 2013. The aim of this study was to assess the incidence, time-points, and risk factors for Rhesus D immunization after the implementation of routine antenatal anti-D prophylaxis, in all women in Finland with antenatal anti-D antibodies detected in 2014-2017.

MATERIAL AND METHODS

In a nationwide population-based retrospective cohort study, the incidence, time-points, and risk factors of anti-D immunizations were analyzed. Information on antenatal screening was obtained from the Finnish Red Cross Blood Service database, and obstetric data from hospital records and the Finnish Medical Birth Register.

RESULTS

The study included a total of 228 women (197 with complete data for all pregnancies). After the implementation of routine antenatal anti-D prophylaxis, the prevalence of pregnancies with anti-D antibodies decreased from 1.52% in 2014 to 0.88% in 2017, and the corresponding incidence of new immunizations decreased from 0.33% to 0.10%. Time-points for detection of new anti-D antibodies before and after 2014 were the first screening sample at 8-12 weeks of gestation in 52% versus 19%, the second sample at 24-26 weeks in 20% versus 50%, and the third screening at 36 weeks in 28% versus 32%.

CONCLUSIONS

The incidence of new anti-D immunizations decreased as expected after the implementation of routine antenatal anti-D prophylaxis. True failures are rare and they mainly occur when the prophylaxis is not given appropriately, suggesting a need for constant education of healthcare professionals on the subject.

The Norwegian experience with nationwide implementation of fetal RHD genotyping and targeted routine antenatal anti-D prophylaxis

OBJECTIVES

To reduce the risk of RhD alloimmunization during the last trimester of pregnancy, a targeted routine antenatal anti-D prophylaxis (RAADP) programme was implemented in Norway in 2016. Here, we present and discuss our experience with the nationwide implementation of the programme, and report sample uptake and preliminary data of de novo anti-D in pregnancy.

BACKGROUND

The targeted RAADP was advised by the academic community and evaluated by the health authorities. A National Working Group has conducted the implementation in the transfusion services and contributed to organise the administration of the antenatal anti-D prophylaxis. Fetal RhD type is determined by non-invasive prenatal testing at gestational week 24, and anti-D prophylaxis is administrated at gestational week 28 only to women with RhD positive fetuses.

METHODS

We describe the implementation process of targeted RAADP in Norway. The sample uptake is calculated by comparing the number of fetal RHD screens with the expected number of samples.

RESULTS

The sample uptake shows regional variations: 88%-100% after 3 years. Promising decrease in de novo anti-D detected during pregnancy is observed.

CONCLUSIONS

Nationwide targeted RAADP is implemented and included in the Norwegian maternity care programme. Compliance to sample uptake should further improve in some regions. A remaining issue to fulfil is the documentation of the accuracy of the fetal RHD-typing at all sites. Post-natal prophylaxis will then be guided by the fetal RHD result. Dedicated registries will ensure data to evaluate the expected reduction in pregnancy-related RhD immunisations, which is the final success criterion of the programme.

Prevalence of rhesus D-negative blood type and the challenges of rhesus D immunoprophylaxis among obstetric population in Ethiopia: a systematic review and meta-analysis

Background

Transplacental or fetomaternal hemorrhage (FMH) may occur during pregnancy or at delivery and lead to immunization to the D antigen if the mother is Rh-negative and the baby is Rh-positive. This can result in hemolytic disease of the fetus and newborn (HDFN) in subsequent D-positive pregnancies. Therefore, the aim of this systematic review and meta-analysis was to estimate distribution of ABO and Rh (D) blood groups among pregnant women in Ethiopia.

Method

We searched PubMed, Google Scholar, EMBASE, Cochrane Library, HINARI, AFRO Library Databases, and African Online Journal databases for all available studies using the following keywords: “High rhesus (Rh(D)) negative frequency”, “ABO blood group distribution”, “haemolytic disease of the newborn (HDN)”, “rh isoimmunization”, “anti-RhD immunoglobulin”, “D-negative pregnancies”, “Frequency”, “ABO and Rh blood group distribution”, “feto-maternal hemorrhage”, “rhesus D negative pregnant mothers”, “kleihauer-betke test (KBT)”, “Neonatal Hyperbilirubinemia”, “non-sensitized RhD-negative pregnant women”, “antenatal anti-D immunoglobulin prophylaxis”, “Hemolytic disease of the newborn (alloimmunization), Ethiopia. The search string was developed using “AND” and “OR” Boolean operators. All published and unpublished observational studies reporting the distribution of ABO and Rh (D) blood groups among pregnant women in Ethiopia were included. The study participants were all pregnant women in Ethiopia, and the main outcome measure of this systematic review and meta-analysis was Rhesus D-negative blood type and ABO blood group distribution among pregnant women in Ethiopia. The data was extracted by the author (AAA) by using a standardized JBI data extraction format. Microsoft Excel (2016), and Stata version 11.0 (Stata Corporation, College Station, Texas, USA) software were used for data entry and analysis, respectively. The random effect model was used for estimating the pooled effects, and the publication bias was assessed by visual inspection of the funnel plots and objectively by using the Egger’s test (i.e. p < 0.05).

Results

One hundred thirty-two articles were identified through electronic database searching. Of which, 34 were excluded due to duplication, 65 through review of titles and abstracts, and 22 full-text articles were excluded for not reporting the outcome variable and other reasons. Finally, 7 were included to estimate the distribution of ABO and Rh (D) blood groups among pregnant women in Ethiopia. The pooled distribution of Rh-negative blood group among pregnant women in Ethiopia was 10.8% (95%CI: 7.53–14.07, I² = 85%, p < 0.001). In the ABO system, type O was the most prevalent 39.9% (37.51–42.38), followed by A (30.59% (26.00–35.18)), B (23.04% (20.03–26.05)), and AB the least (4.82%(3.17–6.47)), in the pattern O > A > B > AB.

Conclusion

The pooled distribution of Rh-negative blood group among pregnant women in Ethiopia was high. Rh alloimmunization remains a major factor responsible for perinatal morbidity in Ethiopia and may result in the compromise of the woman’s obstetric care due to the unaffordability of anti-D immunoglobulin. There is the urgent need for the implementation of universal access to anti-D immunoglobulin for the Rh-negative pregnant population in Ethiopia.

Frequency and clinical significance of red cell antibodies in pregnancy - A prospective study from India

Background

For appropriate management of hemolytic disease of the fetus and newborn (HDFN), it is important to detect irregular red cell antibody in the antenatal period. Though it is a simple one-step method, it is not part of routine antenatal screening in many developing countries. To reiterate the importance of antenatal antibody screening, we have assessed the frequency and clinical significance of irregular red cell antibodies in our patient population.

Materials and Methods

A prospective study was carried out from October 2013 to May 2015 at a tertiary care center from south India. All antenatal samples received by the laboratory for red cell antibody screening were screened using a commercial three-cell screening panel. Antibody identification along with further Immunohematological techniques as required were performed for cases with positive screening results. Neonates of the alloimmunized cases were followed up to determine the clinical significance of the antibody.

Results

A total of 2336 antenatal mothers were screened for red cell antibodies. The overall rate of alloimmunization in the study group was 2.27%. Alloimmunization rate among RhD-negative pregnancies was 6.9%. Other than anti-D (49%), we identified anti-D + anti-C (5%), anti-G (5%), anti-c (5%), anti-E (2%), anti-e (2%), anti-H (Bombay phenotype) (7%), anti-M (2%), anti-Lea (2%), anti-Leb (12%), and autoantibodies (9%) in the maternal serum. Anti-D, anti-D + anti-C, anti-G, anti-c, and anti-H were found to be clinically significant in this study.

Conclusion

This study showed that 1 in 125 RhD-positive pregnancies can develop red cell alloantibodies. Hence, implementing routine antenatal antibody screening irrespective of RhD status is essential.

Clinical practices and outcomes of RhD immunoglobulin prophylaxis following large-volume fetomaternal haemorrhage in Queensland, Australia

BACKGROUND

Guidelines for laboratory assessment of fetomaternal haemorrhage (FMH) was published by the Australian and New Zealand Society of Blood Transfusion (ANZSBT) in 2002. However, data on adherence by practitioners and clinical outcomes are lacking.

AIMS

The primary objective is to examine the follow-up testing and dosing of additional RhD immunoglobulin in RhD negative women who experienced large-volume FMH for whom additional intravenous RhD immunoglobulin was requested in Queensland, Australia. The secondary objectives are to examine the rate and risk factors of RhD alloimmunisation in these women.

MATERIALS AND METHODS

RhD negative women with FMH >6 mL for whom additional dose(s) of intravenous RhD immunoglobulin was requested through Australian Red Cross Lifeblood from February 2007 to February 2018 were identified. For each patient, the volume of FMH, methods and timing of FMH quantitation, dose of RhD immunoglobulin, maternal and cord blood groups were analysed against the corresponding antibody screen and identification.

RESULTS

Following FMH >6 mL, only 15% and 11.5% of cases adhered to current ANZSBT guideline on follow-up testing and supplemental RhD immunoglobulin dosing respectively. Despite the provision of single supplemental RhD immunoglobulin at a ratio of 100 IU to 1 mL fetal red cells, the rate of RhD alloimmunisation in RhD negative women with RhD positive fetus or fetus of unknown RhD status following FMH >6 mL is at least 4%.

CONCLUSIONS

Poor compliance with guidelines for follow-up and management of large-volume FMH may contribute to increased risk of RhD alloimmunisation. Further analysis of data is warranted.

Severe haemolytic disease of a newborn with variant D mimicking blocked-D phenomenon

Anti-D is still the most common antibody causing severe haemolytic disease of the fetus and newborn (HDFN). In a mother with a very high titer of anti-D, antibodies can coat and block the D antigens on the red blood cells of the newborn. This blocking phenomenon prevents agglutination of the D-positive red cells with the IgM anti-D typing reagent, giving false negative results. Here, we report the case of a newborn with variant D phenotype and severe HDFN, which mimicked the blocked-D phenomenon, which, at the first instance, confused both the treating clinicians and the transfusion service personnel.

Single dose v two-dose antenatal anti-D prophylaxis: a randomised controlled trial

OBJECTIVE

To compare rates of detectability of circulating Rh(D)-immunoglobulin (anti-D) at delivery with single and two-dose antenatal anti-D prophylaxis (RAADP) regimens; to compare compliance with the two regimens.

DESIGN

Open label, randomised controlled trial between May 2013 and November 2015.

SETTING, PARTICIPANTS

277 women who attended a tertiary obstetric referral hospital in Perth for antenatal care and were at least 18 years of age, less than 30 weeks pregnant and yet to receive RAADP, Rh(D)-negative (negative antibody screen), and who intended to deliver their baby at the hospital. Exclusion criteria were prior anti-D sensitisation, any contraindication of anti-D administration, and a history of isolated IgA deficiency.

INTERVENTIONS

One 1500 IU anti-D dose at 28 weeks of pregnancy (single dose regimen); two doses of 625 IU each at 28 and 34 weeks of pregnancy (two-dose regimen).

MAIN OUTCOME MEASURES

The primary outcome was the proportion of women with detectable anti-D levels at delivery; the secondary outcome was compliance with the allocated RAADP regimen.

RESULTS

Circulating anti-D was detectable at delivery in a greater proportion of women in the two-dose group (111 of 129, 86%) than in the single dose group (70 of 125, 56%; P < 0.001). Compliance was not significantly different between the single dose (86 of 138, 61%) and two-dose groups (70 of 139, 50%; P = 0.06).

CONCLUSIONS

The two-dose RAADP schedule currently recommended in Australia provides better protection against Rh(D) sensitisation than a one-dose regimen.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry (ACTRN12613000661774).

Red Blood Cell Alloimmunization in the Pregnant Patient

Alloimmunization to red blood cell (RBC) antigens represents a challenge for physicians caring for women of child bearing potential. Exposure to non-self RBC antigens may occur during transfusion or pregnancy leading to the development of antibodies. If a subsequent fetus bears that antigen, maternal antibodies may attack the fetal red blood cells causing red cell destruction and clinically significant hemolytic disease of the fetus and newborn (HDFN). In the most severe cases, HDFN may result in intrauterine fetal demise due to high output cardiac failure, effusions and ascites, known as "hydrops fetalis". This article reviews strategies for management and prevention of RBC alloimmunization in women of child bearing potential.

Predicting anti-RhD titers in donors: Boostering response and decline rates are personal

Background

Anti-RhD immunised donors provide anti-RhD immunoglobulins used for the prevention of rhesus disease. These donors are periodically hyper-immunised (boostered) to retain a high titer level of anti-RhD.

Study design and methods

We analysed anti-RhD donor records from 1998 to 2016, consisting of 30,116 anti-RhD titers from 755 donors, encompassing 3,372 booster events. Various models were fit to these data to allow describing the anti-RhD titers over time.

Results

A random effects model with a log-linear anti-RhD titer decline over time and a saturating titer response to boostering is shown to fit the data well. This model contains two general model parameters, relating timing and maximum of the booster effect, as well as two parameters characterizing the individual donor, namely how fast the booster effect saturates with current titer and the anti-RhD decline rate. The average individual log₂ decline is 0.55 per year, i.e. a 32% decline in absolute titer, with half of the donors declining between 13% and 41% per year. Their anti-RhD titer peaks around 26 days following a booster event. Boostering response reduces with higher titers at boostering; at median titer (log₂ 11) the mean increase per booster is log₂ 0.38, that is from an absolute titer of 2048 to 2665 (+30%), with half of all donors increasing between 16% and 65% in their titer.

Conclusion

The model describes anti-RhD titer change per individual with only four parameters, two of which are donor specific. This information can be used to enhance the blood bank’s immunisation programme, by deriving individualized immunization policies in which boostering is adjusted to the anticipated anti-RhD decline, effectiveness of boostering and titer levels required.

ABO incompatibility and RhIG immunoprophylaxis protect against non-D alloimmunization by pregnancy

BACKGROUND

Hemolytic disease of the fetus and newborn (HDFN) is caused by maternal antibodies against fetal red blood cell antigens, most often anti-D, -K, or -c. ABO incompatibility between mother and child and anti-D immunoprophylaxis (RhIG) are known to reduce the risk of D immunization and subsequent HDFN. However, no immunoprophylaxis has been developed to prevent non-D immunizations.

STUDY DESIGN AND METHODS

We evaluated whether ABO incompatibility has a preventive effect on formation of non-D alloantibodies, by performing a case-control study including pregnant women with newly detected non-D antibodies, identified within a nationwide data set, immunized during their first pregnancy and/or delivery. Subsequently, we assessed a possible protective effect of RhIG in a subgroup with non-Rh antibodies only. The proportions of previous ABO incompatibility and of RhIG administrations of these women were compared to the known rate of 19.4% ABO incompatibility and 9.9% RhIG administrations (D- women carrying a D+ child) in the general population of pregnant women.

RESULTS

A total of 11.9% of the 232 included immunized women had a possible ABO incompatibility in their first pregnancy (vs. expected 19.4%; 95% confidence interval [CI], 7.3-18.8; p = 0.036). Furthermore, 1.0% women with non-Rh antibodies were D-, delivered a D+ child, and had therefore received RhIG, whereas 9.9% was expected (95% CI, 0.18-5.50; p = 0.003).

CONCLUSION

We found that ABO incompatibility and RhIG reduce the risks not only for D, but also for non-Rh immunizations, suggesting that antibody-mediated immune suppression in this condition is not antigen specific.

Mild-to-moderate foeto-maternal haemorrhage in the third trimester and at term of pregnancy: quantitative determination and clinical-diagnostic evaluation

BACKGROUND

Foeto-maternal haemorrhage (FMH), a gestational event that occurs before or during delivery, consists of a loss of foetal blood into the maternal circulation. FMH occurs more frequently during the third trimester or labour both in normal and complicated pregnancies. In the case of alloimmunisation, the maternal immunological response and the severity of the resulting foetal or neonatal disease depend on the amount of foetal blood that passes into the maternal circulation. The aim of this study was to determine FMH in the third trimester and at term of pregnancy and to evaluate the role of clinical and ultrasound markers in the prediction of FMH.

MATERIALS AND METHODS

FMH was quantified by cytofluorimetric testing at 28 to 35 weeks of gestation in 223 women and at term in 465 women, all with risk factors. Foetal evaluation included foetal movement profile, middle cerebral artery peak velocity of systolic blood flow (MCA-PSV) and cardiotocographic monitoring.

RESULTS

All women tested negative for FMH in the third trimester. Four patients (0.9%) tested positive at term, with estimated volumes of bleeding of 2.2, 8.1, 12.3 and 39.8 mL. Three FMH cases (75%) had a non-reassuring cardiotocography compared to 8.9% (42/461) of women without FMH (p=0.003) and two FMH cases reported a reduction in foetal movements reduction compared to four of those without FMH (p=0.001). Mean MCA-PSV was normal in both the groups with and without FMH (p=0.22).

DISCUSSION

FMH is rare in pregnancy and at term. Cytofluorimetric testing is a specific method to detect mild-to-moderate FMH even when the MCA-PSV is not informative. Mild-to-moderate FMH is significantly associated with reduced foetal movements and non-reassuring cardiotocographic monitoring.

Antigen specificity determines anti-red blood cell IgG-Fc alloantibody glycosylation and thereby severity of haemolytic disease of the fetus and newborn

Haemolytic disease of the fetus and newborn (HDFN) is a severe disease in which fetal red blood cells (RBC) are destroyed by maternal anti-RBC IgG alloantibodies. HDFN is most often caused by anti-D but may also occur due to anti-K, -c- or -E. We recently found N-linked glycosylation of anti-D to be skewed towards low fucosylation, thereby increasing the affinity to IgG-Fc receptor IIIa and IIIb, which correlated with HDFN disease severity. Here, we analysed 230 pregnant women with anti-c, -E or -K alloantibodies from a prospective screening cohort and investigated the type of Fc-tail glycosylation of these antibodies in relation to the trigger of immunisation and pregnancy outcome. Anti-c, -E and -K show - independent of the event that had led to immunisation - a different kind of Fc-glycosylation compared to that of the total IgG fraction, but with less pronounced differences compared to anti-D. High Fc-galactosylation and sialylation of anti-c correlated with HDFN disease severity, while low anti-K Fc-fucosylation correlated with severe fetal anaemia. IgG-Fc glycosylation of anti-RBC antibodies is shaped depending on the antigen. These features influence their clinical potency and may therefore be used to predict severity and identify those needing treatment.

Rare problems with RhD immunoglobulin for postnatal prophylaxis after large fetomaternal haemorrhage

We report a case of unusually large fetomaternal haemorrhage in a RhD- patient; of symptomatic non-sustained haemolysis of fetal red cells in the maternal circulation with infusion of intravenous high-dose RhD immunoglobulin; and of a failure to prevent RhD alloimmunisation. The haemolytic reaction is not previously reported in this patient group and we suggest would be limited to patients where the number of fetal red cells in the circulation is high. We advocate caution in treatment and spaced dosing of RhD immunoglobulin where the required dose is high, and refer readers to the WinRhoSDF™ RhD immunoglobulin product information for their updated dosing recommendations. There is a need for better understanding of pathophysiology and RhD immunoglobulin effects, to further reduce alloimmunisation rates, and we support the reporting of prophylaxis failures to haemovigilance programmes as is in place in the United Kingdom.

Hemolytic disease of the fetus and newborn: managing the mother, fetus, and newborn

Hemolytic disease of the fetus and newborn (HDFN) affects 3/100 000 to 80/100 000 patients per year. It is due to maternal blood group antibodies that cause fetal red cell destruction and in some cases, marrow suppression. This process leads to fetal anemia, and in severe cases can progress to edema, ascites, heart failure, and death. Infants affected with HDFN can have hyperbilirubinemia in the acute phase and hyporegenerative anemia for weeks to months after birth. The diagnosis and management of pregnant women with HDFN is based on laboratory and radiographic monitoring. Fetuses with marked anemia may require intervention with intrauterine transfusion. HDFN due to RhD can be prevented by RhIg administration. Prevention for other causal blood group specificities is less studied.

Haemolytic disease of the fetus and newborn

Haemolytic Disease of the Fetus and Newborn (HDFN) is caused by maternal alloimmunization against red blood cell antigens. In severe cases, HDFN may lead to fetal anaemia with a risk for fetal death and to severe forms of neonatal hyperbilirubinaemia with a risk for kernicterus. Most severe cases are caused by anti-D, despite the introduction of antental and postnatal anti-D immunoglobulin prophylaxis. In general, red blood cell antibody screening programmes are aimed to detect maternal alloimmunization early in pregnancy to facilitate the identification of high-risk cases to timely start antenatal and postnatal treatment. In this review, an overview of the clinical relevance of red cell alloantibodies in relation to occurrence of HDFN and recent views on prevention, screening and treatment options of HDFN are provided.

Assessment of feto-maternal hemorrhage among rhesus D negative pregnant mothers using the kleihauer-betke test (KBT) and flow cytometry (FCM) in Addis Ababa, Ethiopia

BACKGROUND

This study aimed to assess fetomaternal hemorrhage (FMH) among RhD negative pregnant mothers using two techniques, Kleihauer-Betke (KBT) and Flow cytometry (FCM). To determine if patient-specific doses of prophylactic anti-D warrant further investigation in Ethiopia and wider Africa.

METHODS

Hospital- based cross-sectional study was conducted among 75 RhD negative pregnant mothers using convenient sampling technique.

RESULT

FMH has been detected in 52% and 60% by KBT and FCM techniques, respectively. The volume of FMH quantified in the majority of the cases (92.5% and 87%) was <10 mL fetal blood while >30 mL in 1.3% (1/75) and 2.7% (2/75) as calculated by KBT and FCM, respectively. The FMH calculated by the two methods have good correlation; r = 0.828 (p = 0.000) for categorized and r = 0.897 (p = 0.000) for continuous values and the agreement between the FCM and KBT was moderate with kappa (κ) value of 0.53 (p = 0.000).

CONCLUSION

Most of FMH calculated (<10 mL) could have been neutralized by lower doses which might have lower costs than administering 300 μg dose which is currently in practice in our country for affording mothers. Besides, it also showed that the volume of FMH was >30 mL in 1.3% and 2.7% of the cases as calculated by KBT and FCM, respectively, which need more than 300 μg dose RhIG for neutralization. Further investigation into the cost- effectiveness and scalability of patient- specific dosing of prophylactic anti-D appears warranted.

Accurate quantitation of D+ fetomaternal hemorrhage by flow cytometry using a novel reagent to eliminate granulocytes from analysis

BACKGROUND

Quantitation of fetomaternal hemorrhage (FMH) is performed to determine the dose of prophylactic anti-D (RhIG) required to prevent D immunization of D- women. Flow cytometry (FC) is the most accurate method. However, maternal white blood cells (WBCs) can give high background by binding anti-D nonspecifically, compromising accuracy.

STUDY DESIGN AND METHODS

Maternal blood samples (69) were sent for FC quantitation of FMH after positive Kleihauer-Betke test (KBT) analysis and RhIG administration. Reagents used were BRAD-3-fluorescein isothiocyanate (FITC; anti-D), AEVZ5.3-FITC (anti-varicella zoster [anti-VZ], negative control), anti-fetal hemoglobin (HbF)-FITC, blended two-color reagents, BRAD-3-FITC/anti-CD45-phycoerythrin (PE; anti-D/L), and BRAD-3-FITC/anti-CD66b-PE (anti-D/G). PE-positive WBCs were eliminated from analysis by gating. Full blood counts were performed on maternal samples and female donors.

RESULTS

Elevated numbers of neutrophils were present in 80% of patients. Red blood cell (RBC) indices varied widely in maternal blood. D+ FMH values obtained with anti-D/L, anti-D/G, and anti-HbF-FITC were very similar (r = 0.99, p < 0.001). Correlation between KBT and anti-HbF-FITC FMH results was low (r = 0.716). Inaccurate FMH quantitation using the current method (anti-D minus anti-VZ) occurred with 71% samples having less than 15 mL of D+ FMH (RBCs) and insufficient RhIG calculated for 9%. Using two-color reagents and anti-HbF-FITC, approximately 30% patients had elevated F cells, 26% had no fetal cells, 6% had D- FMH, 26% had 4 to 15 mL of D+ FMH, and 12% patients had more than 15 mL of D+ FMH (RBCs) requiring more than 300 μg of RhIG.

CONCLUSION

Without accurate quantitation of D+ FMH by FC, some women would receive inappropriate or inadequate anti-D prophylaxis. The latter may be at risk of immunization leading to hemolytic disease of the newborn.

Targeted routine antenatal anti-D prophylaxis in the prevention of RhD immunisation--outcome of a new antenatal screening and prevention program

Objective

To estimate the incidence of RhD immunisation after implementation of first trimester non-invasive fetal RHD screening to select only RhD negative women carrying RHD positive fetuses for routine antenatal anti-D prophylaxis (RAADP).

Materials and Methods

We present a population-based prospective observational cohort study with historic controls including all maternity care centres and delivery hospitals in the Stockholm region, Sweden. All RhD negative pregnant women were screened for fetal RHD genotype in the first trimester of pregnancy. Anti-D immunoglobulin (250–300 µg) was administered intramuscularly in gestational week 28–30 to participants with RHD positive fetuses. Main outcome measure was the incidence of RhD immunisation developing during or after pregnancy.

Results

During the study period 9380 RhD negative women gave birth in Stockholm. Non-invasive fetal RHD genotyping using cell-free fetal DNA in maternal plasma was performed in 8374 pregnancies of which 5104 (61%) were RHD positive and 3270 (39%) RHD negative. In 4590 pregnancies with an RHD positive test the women received antenatal anti-D prophylaxis. The incidence of RhD immunisation in the study cohort was 0.26 percent (24/9380) (95% CI 0.15–0.36%) compared to 0.46 percent (86/18546) (95% CI 0.37 to 0.56%) in the reference cohort. The risk ratio (RR) for sensitisation was 0.55 (95% CI 0.35 to 0.87) and the risk reduction was statistically significant (p = 0.009). The absolute risk difference was 0.20 percent, corresponding to a number needed to treat (NNT) of 500.

Conclusions

Using first trimester non-invasive antenatal screening for fetal RHD to target routine antenatal anti-D prophylaxis selectively to RhD negative women with RHD positive fetuses significantly reduces the incidence of new RhD immunisation. The risk reduction is comparable to that reported in studies evaluating the outcome of non selective RAADP to all RhD negative women. The cost-effectiveness of this targeted approach remains to be studied.

Implementing non-invasive RHD genotyping on cell-free foetal DNA from maternal plasma: the Pavia experience

BACKGROUND

The occurrence of cell-free foetal DNA in maternal circulation opens new possibilities in non-invasive antenatal diagnosis. Real-time polymerase chain reaction (PCR) analysis is an useful approach to foetal RhD blood group determination, thus being important in the prevention of haemolytic disease of foetus and new-born (HDFN).

STUDY DESIGN AND METHODS

Using real-time PCR assays we typed 20 samples of plasma, provided in a blinded fashion, from the International Reference Laboratory, two plasma samples sent by the "2010 Workshop on Molecular Blood Group Genotyping"; seven samples from D-negative mothers at the 16th week of gestation provided by our Hospital as prospective validation cases, and two plasma samples received from the "1(st) Collaborative study establishing the sensitivity standard for non-invasive prenatal determination of foetal RHD genotype". To confirm the RHD typing of the seven prospective samples, PCR with sequence specific primers (PCR-SSP) was applied on genomic DNA from amniocytes (5 cases) and paternal peripheral blood (2 cases).

RESULTS

The results for the 31 investigated samples showed 100% concordance. Our measurable benefits were: confidence with a new technology, awareness of having gained the European standard level and increased self-assurance regarding the introduction of this typing technique in prenatal diagnostics.

DISCUSSION

These results demonstrate the feasibility and accuracy of our validation protocol. RHD typing on cell-free foetal DNA is a procedure which requires particular care and a great degree of expertise for diagnostic use. International collaborations are essential for monitoring the performance of laboratories in the absence of specific quality control programmes.

Reconsidering fetal and neonatal alloimmune thrombocytopenia with a focus on screening and prevention

Uncertainty regarding the pathophysiology of fetal and neonatal alloimmune thrombocytopenia (FNAIT) has hampered the decision regarding how to identify, follow-up and treat the women and children with this potentially serious condition. Since knowledge of the condition is derived mainly from retrospective studies, understanding of the natural history of this condition remains incomplete. General screening programs for FNAIT have still not been introduced, mainly because of a lack of reliable risk factors and effective treatment. Now, several prospective screening studies involving up to 100,000 pregnant women have been published and the results have changed the understanding of the pathophysiology of FNAIT and, thereby, the approach toward diagnostics, prevention and treatment in a more appropriate way.

The challenges of meeting the blood transfusion requirements in Sub-Saharan Africa: the need for the development of alternatives to allogenic blood

As a resource, allogenic blood has never been more in demand than it is today. Escalating elective surgery, shortages arising from a fall in supply, a lack of national blood transfusion services, policies, appropriate infrastructure, trained personnel, and financial resources to support the running of a voluntary nonremunerated donor transfusion service, and old and emerging threats of transfusion-transmitted infection, have all conspired to ensure that allogenic blood remains very much a vital but limited asset to healthcare delivery particularly in Sub-Saharan Africa. This is further aggravated by the predominance of family replacement and commercially remunerated blood donors, rather than regular benevolent, nonremunerated donors who give blood out of altruism. The demand for blood transfusion is high in Sub-Saharan Africa because of the high prevalence of anemia especially due to malaria and pregnancy-related complications. All stakeholders in blood transfusion have a significant challenge to apply the best available evidenced-based medical practices to the world-class management of this precious product in a bid to using blood more appropriately. Physicians in Sub-Saharan Africa must always keep in mind that the first and foremost strategy to avoid transfusion of allogenic blood is their thorough understanding of the pathophysiologic mechanisms involved in anemia and coagulopathy, and their thoughtful adherence to the evidenced-based good practices used in the developed world in a bid to potentially reduce the likelihood of allogenic blood transfusion in many patient groups. There is an urgent need to develop innovative ways to recruit and retain voluntary low-risk blood donors. Concerns about adverse effects of allogenic blood transfusion should prompt a review of transfusion practices and justify the need to search for transfusion alternatives to decrease or avoid the use of allogenic blood. These strategies should include the correction of anemia using pharmacological measures (use of antifibrinolytics to prevent bleeding and the use of erythropoietin and oral and intravenous iron to treat anemia) use of nonpharmacologic measures (preoperative autologous blood transfusion, perioperative red blood cell salvage and normothermia to reduce blood loss in surgical patients). All these strategies will help optimize the use of the limited blood stocks.

Rh isoimmunization in Sub-Saharan Africa indicates need for universal access to anti-RhD immunoglobulin and effective management of D-negative pregnancies

Transplacental or fetomaternal hemorrhage (FMH) may occur during pregnancy or at delivery and lead to immunization to the D antigen if the mother is Rh-negative and the baby is Rh-positive. This can result in hemolytic disease of the fetus and newborn (HDFN) in subsequent D-positive pregnancies. The aim of this study is to highlight the challenges associated with the effective management and prevention of Rh alloimmunization among Rh-negative women in Sub-Saharan Africa. In most Sub-Saharan African countries, there is poor and sometimes no alloimmunization prevention following potentially sensitizing events and during medical termination of pregnancy in Rh-negative women. Information about previous pregnancies and termination are often lacking in patients' medical notes due to poor data management. These issues have made the management of Rh-negative pregnancy a huge challenge. Despite the fact that the prevalence of Rh-negative phenotype is significantly lower among Africans than Caucasians, Rh alloimmunization remains a major factor responsible for perinatal morbidity in Sub-Saharan Africa and may result in the compromise of the woman's obstetric care due to the unaffordability of anti-D immunoglobulin. There is the urgent need for the implementation of universal access to anti-D immunoglobulin for the Rh-negative pregnant population in Africa. Anti-D immunoglobulin should be available in cases of potentially sensitizing events such as amniocentesis, cordocentesis, antepartum hemorrhage, vaginal bleeding during pregnancy, external cephalic version, abdominal trauma, intrauterine death and stillbirth, in utero therapeutic interventions, miscarriage, and therapeutic termination of pregnancy. There is also the need for the availability of FMH measurements following potentially sensitizing events. The low-cost acid elution method, a modification of the Kleihauer-Betke (KB) test, can become a readily available, affordable, and minimum alternative to flow cytometric measurement of FMH. Knowledge of anti-D prophylaxis among obstetricians, biomedical scientist, midwives, traditional birth attendants, pharmacists, and nurses in Africa needs to be improved. This will facilitate quality antenatal and postnatal care offered to Rh-negative pregnant population and improve perinatal outcomes.