Guideline for blood grouping and antibody testing in pregnancy

Immunohaematological conundrums in obstetrics from transfusion services viewpoint in Armed Forces setup

Background

Obstetrics as a speciality has a very long association with the transfusion services and poses its own set of immunohematological (IHL) challenges. A study was carried out to evaluate the spectrum of IHL issues in obstetrics in our setup and to suggest a way forward.

Methods

This study was carried out in a transfusion services setup catering to antenatal care (ANC) clientele in two tertiary-level health care setups. Samples were collected from all ANC patients requiring transfusion and patients reporting for Indirect Coombs Test (ICT). Data included ICT positive cases with implicated alloantibodies, those requiring specialised procedures and the foetal outcome. The results were described using descriptive statistics by frequencies and percentages.

Results

A total of 4683 eligible samples were included in the study, out of 21,893 antenatal patients visiting our setup during study period. One hundred thirty-six ANC patient samples were found to be ICT positive. The most common single alloantibody was anti-D (n = 77, 57.5%). Double antibody positivity was found in 28 patients. Multiple alloantibodies were found in 1 patient. Up to 48% of these allo-anti D cases necessitated specialised procedures.

Conclusion

The IHL issues of obstetrics faced in our setup are no less than that in Indian population. We have much higher frequency of double alloantibody in our ANC population. The authors propose that all multiparous ANC patients, especially with a history of transfusion, irrespective of Rh D status should be screened for irregular alloantibodies to circumvent these issues and the last-minute rush for provision of compatible units.

Irregular erythrocyte antibodies among antenatal women and their neonatal outcome at a tertiary care hospital in Northern India

BACKGROUND

Red blood cell alloimmunisation during the pregnancy is a significant cause for neonatal mortality and morbidity. This study was planned to determine the prevalence and specificity of irregular erythrocyte antibodies in antenatal mothers and their neonatal outcome.

METHODS

In this observational study, blood grouping and red cell antibody screening of mothers were performed at first visit and after 28 weeks of gestation and positive cases were identified and followed up monthly till delivery by repeating antibody titre and middle cerebral artery-peak systolic velocity. After delivery of alloimmunised mothers, cord blood haemoglobin, bilirubin and direct antiglobulin tests (DAT) were analysed and further outcome of neonate was recorded.

RESULTS

Among 652 registered antenatal cases, 18 multigravida women were found to be alloimmunised, accounting to prevalence of 2.8%. Most common alloantibody identified was anti D (>70%) followed by anti-Le^a, anti-C, anti-Le^b, anti-E and anti-Jk^a. Only 47.7% Rh D negative women received anti-D prophylaxis during previous pregnancies or whenever indicated. DAT was positive in 56.2% of neonates. Among nine DAT positive neonates, two early neonatal deaths due to severe anaemia were observed following birth resuscitation. Four antenatal mothers required intrauterine transfusion in view of fetal anaemia while three neonates received double volume exchange transfusion and top up transfusions after birth.

CONCLUSIONS

This study emphasises importance of red cell antibody screening for all multigravida antenatal women at registration of pregnancy and additionally at 28 weeks or later in high-risk cases irrespective of RhD status.

Non-Invasive Prenatal Fetal Blood Group Genotype and Its Application in the Management of Hemolytic Disease of Fetus and Newborn: Systematic Review and Meta-Analysis

Hemolytic disease of fetus and newborn (HDFN) imposes great healthcare burden being associated with maternal alloimmunization against parental-inherited fetal red blood cell antigens causing fetal anemia or death. Noninvasive prenatal analysis (NIPT) provides safe fetal RHD genotyping for early identification of risk pregnancies and proper management guidance. We aimed to conduct systematic review and meta-analysis on NIPT's beneficial application, in conjunction with quantitative maternal alloantibody analysis, for early diagnosis of pregnancies at risk. Search for relevant articles was done in; PubMed/Medline, Scopus, and Ovid (January 2006April 2020), including only English-written articles reporting reference tests and accuracy data. Nineteen eligible studies were critically appraised. NIPT was estimated highly sensitive/specific for fetal RHD genotyping beyond 11-week gestation. Amplifications from ≥2 exons are optimum to increase accuracy. NIPT permits cost-effectiveness, precious resources sparing, and low emotional stress. Knowledge of parental ethnicity is important for correct NIPT result interpretations and quantitative screening. Cut-off titer ≥8-up-to-32 is relevant for anti-D alloantibodies, while, lower titer is for anti-K. Alloimmunization is influenced by maternal RHD status, gravida status, and history of adverse obstetrics. In conclusion, NIPT allows evidence-based provision of routine anti-D immunoprophylaxis and estimates potential fetal risks for guiding further interventions. Future large-scale studies investigating NIPT's non-RHD genotyping within different ethnic groups and in presence of clinically significant alloantibodies are needed.

Survey of newborn direct antiglobulin testing practice in United States and Canadian transfusion services

BACKGROUND

We hypothesized that variability in practice exists for newborn immunohematology testing due to lack of consensus guidelines. We report the results of a survey assessing that variability at hospitals in the United States and Canada.

STUDY DESIGN AND METHODS

An AABB Pediatric Subsection working party developed and validated a survey of newborn immunohematology testing practice. The survey was sent electronically to transfusion service leadership at teaching institutions.

RESULTS

The response rate was 67% (61/91); 56 surveys meeting inclusion criteria were analyzed. Approximately 90% (50/56) were from birth hospitals and 16.1% (9/56) were from pediatric hospitals. Newborn immunohematology testing is ordered as a panel by 66.0% (33/50) of birth hospitals. ABO group and DAT is mandated before discharge in 14/56 (25.0%) and 13/56 (23.2%), respectively. About 76.8% (43/56) selectively perform a DAT according to blood blank or clinical parameters. The most common DAT practices include anti-IgG only testing by 73.2% (41/56) and use of umbilical cord specimen type by 67.9% (38/56). A positive DAT is a critical value for 26.8% (15/56) and followed with eluate testing when a maternal antibody screen is positive for 48.2% (27/56). In the setting of a non-ABO maternal red cell antibody, 55.4% (31/56), phenotype neonatal red cells when the DAT is positive. Group O RBC are transfused irrespective of the DAT result for 82.1%, (46/56).

CONCLUSION

There is variability in newborn immunohematology testing and transfusion practice and potential overutilization of the DAT. Evidence-based consensus guidelines should be developed to standardize practice and to improve safety.

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.

Reproductive health issues in female patients with beta-thalassaemia major: a narrative literature review

β-thalassaemia major (BTM) has a high prevalence worldwide and is associated with considerable morbidity and mortality. The aim of this review is to provide an illustrative overview of the reproductive health and pregnancy related issues in females with β-thalassaemia. A literature search was performed in four international databases (1980-2018) to identify the potentially relevant articles. Common reproductive health disorders are hypo-gonadotrophic hypogonadism, infertility, delayed or absent sexual development, diabetes, hypothyroidism, hypoparathyroidism, osteopenia, preeclampsia, gestational hypertension, polyhydramnios, oligohydramnios, thrombosis, renal failure, peripheral vascular resistance, placenta previa, pleural effusion and pulmonary hypertension. Many of those aspects are related to iron overload and to ineffective erythropoiesis. Foetal complications include neural tube defects, abnormalities in different organs, spontaneous abortion, foetal loss, preterm birth, foetal growth restriction and low birth weight. Antenatal screening and accurate genetic prenatal examinations are effective measures to early diagnosis of thalassaemia and a detailed plan for management of pregnancies in BTM is important for favourable maternal and foetal outcome.

Maternal HPA-1a antibody level and its role in predicting the severity of Fetal/Neonatal Alloimmune Thrombocytopenia: a systematic review

BACKGROUND AND OBJECTIVES

In Caucasians, fetal/neonatal alloimmune thrombocytopenia (FNAIT) is most commonly due to maternal HPA-1a antibodies. HPA-1a typing followed by screening for anti-HPA-1a antibodies in HPA-1bb women may identify first pregnancies at risk. Our goal was to review results from previous published studies to examine whether the maternal antibody level to HPA-1a could be used to identify high-risk pregnancies.

MATERIALS AND METHODS

The studies included were categorized by recruitment strategies: screening of unselected pregnancies or samples analyzed from known or suspected FNAIT patients.

RESULTS

Three prospective studies reported results from screening programmes, and 10 retrospective studies focused on suspected cases of FNAIT. In 8 studies samples for antibody measurement, performed by the monoclonal antibody immobilization of platelet antigen (MAIPA) assay, and samples for determining fetal/neonatal platelet count were collected simultaneously. In these 8 studies, the maternal antibody level correlated with the risk of severe thrombocytopenia. The prospective studies reported high negative predictive values (88-95%), which would allow for the use of maternal anti-HPA-1a antibody level as a predictive tool in a screening setting, in order to identify cases at low risk for FNAIT. However, due to low positive predictive values reported in prospective as well as retrospective studies (54-97%), the maternal antibody level is less suited for the final diagnosis and for guiding antenatal treatment.

CONCLUSION

HPA-1a antibody level has the potential to predict the severity of FNAIT.

A descriptive single-centre experience of the management and outcome of maternal alloantibodies in pregnancy

BACKGROUND

Haemolytic disease of the fetus and newborn (HDFN) occurs when maternal IgG alloantibodies to fetal red blood cell antigens cross the placenta, causing haemolysis in the fetus and/or neonate. After delivery, the main concern is hyperbilirubinaemia, which can cause neurological damage.

OBJECTIVES

To summarise our current management and outcome data to inform health-care professionals counselling women whose pregnancies are at risk of HDFN and to compare these data with relevant studies.

METHODS

This is a retrospective descriptive study of all high-risk pregnancies at risk of HDFN at Guy's and St. Thomas' NHS Foundation Trust (GSTFT) Maternity Unit over a 7-year period. We defined high-risk pregnancies as those in whom anti-D, anti-c, anti-K or high (>32 or doubling strength) titres of all other antibodies were identified.

RESULTS

A total of 130 pregnancies in 112 women were followed up. A single alloantibody was found in 93 pregnancies (71.5%) and multiple alloantibodies in 37 pregnancies (28.5%). Anti-D was most commonly encountered (n = 48, 36.9%), followed by anti-c (n = 31, 23.8%) and anti-E (n = 15, 11.5%). In 65 of 130 pregnancies (50%), antibody concentrations triggered scans to screen for fetal anaemia. Of 130 pregnancies, 6 (4.6%) required intrauterine transfusions, and 31 of 130 (26%) neonates required post-natal intervention. Overall, morbidity was 0.1% and mortality 0.002%.

CONCLUSIONS

This study demonstrates that morbidity and mortality caused by HDFN is minimal. These results are reassuring for women at risk of HDFN as even severely affected cases are successfully managed in most instances. Further studies are needed to identify predictors of disease severity.

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.

Fertility and Pregnancy in Thalassaemia and Sickle Cell Disease. The UK Guidelines

Progressive improvements in the health and survival of patients with thalassaemia and sickle cell disease have increased the reproductive prospects of affected individuals. However, pregnancy in these disorders is associated with significant maternal and fetal risks and expert management is required to ensure good outcomes. In the United Kingdom, it is recognised that the patchy geographical distribution of these conditions poses challenges for access to specialist care, including specialist obstetric services. Guidelines on the pregnancy management of thalassaemia and sickle cell disease in the UK have been published by the Royal College of Obstetricians and Gynaecologists. These guidelines describe the preconceptual, antenatal, intrapartum and postpartum aspects of care. They highlight the high-risk status of pregnancy in these conditions and emphasise the vital importance of specialist multidisciplinary care to the achievement of favourable maternal and fetal outcomes. The guidelines are a valuable resource to healthcare professionals, especially those working in low prevalence areas.

Reassessing critical maternal antibody threshold in RhD alloimmunization: a 16-year retrospective cohort study

OBJECTIVE

To determine the critical maternal antibody threshold for specialist referral in cases of RhD alloimmunization.

METHODS

This was a retrospective cohort study, covering a 16-year period at the national tertiary fetal medicine center for management of alloimmunization. Data concerning RhD alloimmunized pregnant women were extracted from an institutional database and maternal anti-D antibody levels were cross-checked with the national reference laboratory. Fetal hemoglobin (Hb) levels were determined only at the first intrauterine transfusion (IUT) and were compared with the pretransfusion maternal anti-D antibody level (IU/mL). Sensitivity, specificity and positive and negative predictive values of maternal antibody thresholds for detecting moderate to severe (Hb ≤ 0.64MoM) fetal anemia were calculated.

RESULTS

Between 1996 and 2011, 66 women underwent a first IUT for RhD alloimmunization at our institution. The highest serum anti-D antibody level was extracted for 208 RhD alloimmunized women who did not require IUT during the last 10 years of the study period. The traditional maternal antibody threshold of > 15 IU/mL failed to detect 20% of cases of moderate to severe fetal anemia. The ≥ 4 IU/mL threshold had 100% sensitivity but a 45% false-positive rate. The optimal anti-D antibody threshold for specialist referral in our population was ≥ 6 IU/mL; at this level, no case of moderate to severe anemia was missed and specificity was 61%. Use of this threshold would have eliminated 10% of referrals to our fetal medicine unit without compromising fetal outcomes.

CONCLUSIONS

Setting the critical maternal RhD antibody level at >15 IU/mL does not provide sufficient sensitivity. The lower threshold of ≥ 4 IU/mL, though sensitive, is associated with a 45% false-positive rate. In our population, a threshold of ≥ 6 IU/mL minimizes false-positive referrals while maintaining 100% sensitivity for moderate to severe fetal anemia.

A correlation between severe haemolytic disease of the fetus and newborn and maternal ABO blood group

OBJECTIVE

To analyse anti-D quantification levels and frequency of intrauterine transfusion (IUT), per maternal ABO blood group.

BACKGROUND

Maternally derived red cell allo-antibodies can target fetal red cell antigens in utero leading to haemolytic disease and fetal anaemia. When a clinically significant allo-antibody is formed the priority is ascertaining the risk to the fetus and maternal ABO blood groups are not considered relevant.

MATERIALS AND METHODS

This was a 10-year retrospective, observational study carried out on women referred for anti-D quantification (n = 1106), and women whose fetuses required an IUT to treat fetal anaemia (n = 62) due to anti-D, in the Republic of Ireland.

RESULTS

Relative to the overall incidence of RhD allo-immunisation by blood group, women of blood group A were more likely to require IUT compared with those who were blood group O (P = 0.002).

CONCLUSION

It is known that ABO feto-maternal compatibility can influence the incidence and level of red cell allo-antibodies in pregnancy; however, it does not account for the significantly high rate of severe haemolytic disease requiring IUT seen in blood group A women.

Hemolytic disease of the newborn caused by anti-Wright (anti-Wra): case report and review of literature

Antibodies to red cell antigens that are found at low frequency in the general population are rare causes of hemolytic disease of the newborn. To understand how to detect these cases, we provide a basic review of routine antenatal maternal antibody testing and report a case of a neonate with severe HDN caused by anti-Wright (anti-Wra), successfully managed with transfusion, phototherapy, and high-dose intravenous immunoglobulin. When hemolysis in a newborn is suspected in the absence of major blood group incompatibility or commonly detected maternal red cell antibodies, a direct antiglobulin test should be performed. A positive DAT should alert the clinician to the presence of maternal antibodies against low-incidence antigens. Antibodies to the Wra antigen are one such rare cause of HDN.