Racial/ethnic disparities among women receiving intrauterine transfusions for alloimmunization at a single fetal treatment center.

Disparities are prevalent in numerous areas of healthcare. We sought to investigate whether there were racial/ethnic disparities among pregnant women with the most severe form of alloimmunization who require intrauterine transfusions (IUT). We reviewed patients who underwent IUT for alloimmunization at a single fetal treatment center between 2015 and 2020. This "IUT cohort" was compared to an "Alloimmunization cohort": patients seen at our institution with a diagnosis of alloimmunization during pregnancy, who did not receive IUT. We collected maternal demographics including self-identified race/ethnicity and primary language, transfusion, and antibody characteristics. The cohorts were compared using unpaired t-tests, Mann-Whitney tests, and Fischer's exact tests, as appropriate. The IUT cohort included 43 patients and the alloimmunization cohort included 1049 patients. Compared to the alloimmunization cohort, there were significantly more patients of Latina descent in the IUT cohort (23.3% vs. 3.4%, p < .0001), and more non-English speakers (18.6% vs. 4.6%, p = .001). Twenty-one percent (9/43) of patients had immigrated to the United States, all of whom had pregnancies or miscarriages in their country of origin. A third of patients had new antibodies identified on serial screens during the current pregnancy. Significantly more women of Latina ethnicity and non-English speakers required IUTs compared to the cohort of women with alloimmunization. Insufficient access to care prior to arriving in the United States and among racial and ethnic minorities in the United States may contribute to these findings. Providers should be cognizant of potential, racial, and ethnic inequalities among women receiving intrauterine transfusions.

Evaluating automated titre score as an alternative to continuous flow analysis for the prediction of passive anti-D in pregnancy.

OBJECTIVES: To evaluate the potential of the automated titre score (TS) as an alternative method to continuous flow analysis (CFA) for the prediction of the nature of anti-D in pregnancy. BACKGROUND: The 2016 revised British Society for Haematology (BSH) antenatal guidelines recommended a measurement of anti-D concentration by CFA to ensure the detection of potential immune anti-D. Due to high referral costs and resource pressures, uptake has been challenging for hospital laboratories. Serious Hazards of transfusion (SHOT) data have previously shown that this has contributed to missed antenatal follow ups for women with immune anti-D and neonates affected by haemolytic disease of the fetus/newborn. METHODS/MATERIALS: In this multicentre comparative study, samples referred for CFA quantification were also tested by an ORTHO VISION automated anti-D indirect antiglobulin test (IAT) serial dilution and then converted to TS. CFA results and history of anti-D prophylaxis were used to categorise samples as passive or immune, with the aim of determining a potential TS cut-off for CFA referral of at risk patients. RESULTS: Five UK National Health Service (NHS) trusts generated a total of 196 anti-D TS results, of which 128 were classified as passive and 68 as immune. Diagnostic testing of CFA and TS values indicated a TS cut-off of 35 to assist in distinguishing the nature of anti-D. Using this cut-off, 175 (89%) results were correctly assigned into the passive or immune range, giving a specificity of 92.19% and a negative predictive value of 91.47%. CONCLUSION: TS in conjunction with clinical and anti-D prophylaxis history can be used as a viable and cost-effective alternative to CFA in a hospital laboratory setting.

Noninvasive fetal RHD genotyping to guide targeted anti-D prophylaxis-an external quality assessment workshop.

BACKGROUND AND OBJECTIVES: Fetal RHD genotyping of cell-free fetal DNA from RhD-negative pregnant women can be used to guide targeted antenatal and postnatal anti-D prophylaxis for the prevention of RhD immunization. To assure the quality of clinical testing, we conducted an external quality assessment workshop with the participation of 28 laboratories. MATERIALS AND METHODS: Aliquots of pooled maternal plasma were sent to each laboratory. One sample was positive, and the second sample was negative for fetal RHD, verified by pre-workshop testing using quantitative real-time PCR (qPCR) analysis of RHD exons 4, 5, 7 and 10. Plasma samples were shipped at room temperature. A reporting scheme was supplied for data collection, including questions regarding the methodological setup, results and clinical recommendations. Different methodological approaches were used, all employing qPCR with a total of eight different combinations of RHD exon targets. The samples were tested blindly. RESULTS: Fetal RHD genotyping was performed with no false-negative and no false-positive results. One inconclusive result was reported for the RHD-positive sample, and four inconclusive results were reported for the RHD-negative sample. All clinical conclusions were satisfactory. CONCLUSION: This external quality assessment workshop demonstrates that despite the different approaches taken to perform the clinical assays, fetal RHD genotyping is a reliable laboratory assay to guide targeted use of Rh prophylaxis in a clinical setting.

Evaluation of 2-column agglutination versus conventional tube technique for antibody screening.

The study aimed to determine the specificity and sensitivity of the Ortho BioVue two-column agglutination system for the detection of low concentrations of clinically significant antibodies in serum. The BioVue system was compared with the conventional tube technique (LISS-Coombs indirect antiglobulin test), and the two-stage Papenzyme test was used to resolve discrepancies between the two methods. We tested 3000 serum samples from randomly selected patients at King Hussein Medical Centre. Both the antibody screening and identification gave negative results in 2952 patients and positive results in 48 patients. We found the BioVue system to be the more sensitive technique. However, if papain enzyme-treated cells were included in the conventional tube technique when applied to antibody screening and identification, both methods would be of comparable sensitivity.

Predicting the severity of haemolytic disease of the newborn: an assessment of the clinical usefulness of the chemiluminescence test.

The ability of the chemiluminescence test (CLT) to predict the severity of haemolytic disease of the newborn (HDN) was determined in 80 alloimmunized pregnant women who delivered antigen-positive babies. In 54 cases of alloimmunization to D, results from the CLT showed better correlation with fetal outcome than anti-D concentration measured by AutoAnalyzer (r = 0.70 and 0.36 respectively). Results from the CLT permitted a threshold level of antibody activity (30%) below which 15/20 babies were unaffected or had mild disease, and only one required transfusion therapy in utero. CLT results above 30% were associated with moderate or severe disease in all cases. Results from the AutoAnalyzer proved a less reliable predictor of disease severity; three women with anti-D levels > 20 iu/ml delivered unaffected babies, and two women with anti-D levels < 10 iu/ml delivered babies who had required transfusion in utero. The clinical usefulness of the CLT derives from the possibility of avoiding invasive monitoring procedures in women with high levels of anti-D which is relatively non-functional.

Serological characteristics of partial D antigen category VI in 8 unrelated blood donors.

Classification of subjects with a partial D antigen is traditionally performed with immune anti-D sera. The development of monoclonal antibodies enables a fine analysis to be made of the specificity of the epitopes that are present or missing in these cases. A systematic search in a Caucasian donor population of 17,500 revealed 8 unrelated male individuals (frequency 0.05%) with a red cell phenotype characteristic of partial D category VI, but without anti-D in their serum. The relation to the 'classic' partial D category VI was investigated and is discussed, as is the observed serological heterogeneity of the partial D category VI group. Clinical consequences for the prevention of immunization of these subjects are mentioned.