Anti-M Alloimmunization in Pregnancy: An Unusual Cause of Bad Obstetric History

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.

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.

Hemolytic disease of the fetus and newborn due to alloanti-M: three Chinese case reports and a review of the literature

BACKGROUND

Alloanti-M was once regarded as not clinically significant, with a few exceptions in extremely rare cases. However, an increasing number of cases of severe hemolytic disease of the fetus and newborn (HDFN), resulting in fetal hydrops and recurrent abortion caused by alloanti-M, have been reported mainly in the Asian population.

STUDY DESIGN AND METHODS

Three pregnant Chinese women with a history of abnormal pregnancy with hydrops fetalis were encountered. During this pregnancy, a series of clinical examinations and an alloantibody identification against RBCs and platelets were conducted. Intrauterine transfusion and postnatal transfusion were then performed in the fetuses. In addition, the HDFN cases caused by alloanti-M reported in different ethnic groups as well as their clinical and serologic features are also summarized.

RESULTS

Three pregnant women were identified with an M-N+ phenotype and IgM mixed with IgG alloanti-M in serum. Their fetuses were found by ultrasound examination and cord blood testing to have severe anemia. Additionally, an M+N+ phenotype and IgG alloanti-M were detected in the cord blood of the three fetuses with titers ranging from 1:1 to 1:128. Moreover, low reticulocyte counts and negative direct antiglobulin tests were also shown in two of the fetuses. After receiving intrauterine transfusions and postnatal transfusions several times, these three fetuses eventually survived and then healthfully developed in the follow-up tracking.

CONCLUSION

Alloanti-M immunization can cause severe HDFN with hyporegenerative anemia, often seen in the Asian population, and suppression of erythropoiesis might account for it.