Unexpected RBC antibodies found in 1.85% of pregnant women

Unexpected red blood cell (RBC) antibodies present in 1.85% of pregnant women, according to a recent study published in the Asian Journal of Transfusion Science.¹

Following pregnancy, transfusion, or transplant, there is a chance for unexpected RBC antibodies to develop in patients. These antibodies are against the antigen of parental origin presenting in the fetus, potentially impacting subsequent pregnancies.

Currently, data about therapeutic interventions in pregnant women with unexpected antibodies is lacking. Data about interventions in pregnancies with anemia is also necessary, as it is a consequence associated with unexpected RBC antibodies.

In one study, intrauterine transfusions were performed in patients with red cell alloimmunization to determine perinatal survival.² An average number of 2.97 transfusions were reported across the study cohort, with an overall survival of 93% and a mean gestation at delivery of 34.5 ± 1.94 weeks. This indicated the treatment was effective in fetuses with anemia.

To evaluate the prevalence of unexpected antibodies in pregnant women and therapeutic interventions such as intra-uterine transfusion (IUT) or exchange transfusion after birth, investigators conducted a prospective, observational study.¹ Consecutive pregnancies attending the antenatal clinic offering consent were included in the analysis.

Participants received blood testing, with blood collected in a 3-ml ethylenediaminetetraacetic acid tube. Blood group (BG) and antibody screen was performed using Vision (Ortho Clinical Diagnostics, Raritan, NJ, USA), an automated machine.

A 3-cell antibody screening panel was used to conduct antibody screening, with 11-cell ID Panel A (Reagent RBCs, Resolve Panel A) or Panel B (Reagent RBCs, Resolve Panel B) used to identify alloantibodies in positive cases. Telephonic follow-up was provided to these patients for pregnancy and 3-month postdelivery outcomes.¹

Relevant data included age, gravida, para, name of clinicians, BG, prior pregnancy outcome, duration of pregnancy, sensitization history, antibody screen, anti-D immunization dose, antibody titer, and antibody identification. Antibody-positive patients were followed for required intervention and pregnancy outcome.

There were 539 pregnant women included in the final analysis, 59.59% of whom were aged 25 to 35 years, 65.12% were multigravida, and 34.88% were primigravida. Of multigravida women, 41.55% had live birth as their prior reported pregnancy outcome while 23.56% had abortion. Prior transfusion history was reported in 1.11% of patients.¹

Of the 55 Rh-negative cases, only 38.2% received prophylactic Rho (D) immune globulin immunization. Unexpected RBC antibodies were reported in 10 of 539 women, for a prevalence of 1.85%. However, the prevalence was significantly higher in Rh-negative pregnant women at 10.9% vs only 0.83% in Rh-positive pregnant women.

Anti-D was the most common antibody, reported in 6 women. This was followed by anti-C, anti-E, anti-Le, and anti-M, each reported in 1 woman. These antibodies did not cause significant anemia in the fetus among the cohort. The median titer of these antibodies was 16, with a low of 4 and high of 128.¹

Middle cerebral artery peak systolic velocity (MCA PSV) was used to determine anemia, based on an MCA PSV over 1.5 multiples of medians. Anemia was reported in 2 of the 10 women with unexpected antibodies, without any complications during IUT in either woman. Both children were healthy during the 3-month follow-up.

These results indicated a 1.85% prevalence of unexpected RBC antibodies in pregnant women, with 2 in 10 pregnancies impacted by fetal anemia. Investigators concluded this data highlights the importance of transfusion-based interventions in these pregnancies.¹

References

1. Sunil G, Aseem Kumar T, Geet A. Prevalence of unexpected red blood cell antibodies in pregnant women and follow-up of pregnancy outcome in pregnant women treated with intra-uterine transfusion. Asian Journal of Transfusion Science. 2024;18(1):45-50. doi:10.4103/ajts.ajts_46_23
2. Deka D, Dadhwal V, Sharma AK. Perinatal survival and procedure-related complications after intrauterine transfusion for red cell alloimmunization. Arch Gynecol Obstet. 2016;293:967–973. doi:10.1007/s00404-015-3915-7