Maternal red cell antibodies: Incidence and outcomes from a single-centre in North London

NMUH Staff Publications

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<span style="font-size: 10pt;"><span style="color: #4a4a4a; font-family: Lato, "Helvetica Neue", Helvetica, Arial, sans-serif; text-decoration-color: initial;">Red cell allo-antibody testing in pregnancy is crucial in order to assess the risk of haemolytic disease of the foetus and newbown (HDFN), as well as to ensure that the correct blood is available for the mother. Certain alloantibodies, such as anti-D, are well established as potential triggers for HDFN. Some cause a more profound foetal anaemia, others are more likely to trigger problems in the neonatal period, whilst another group of allo-antibodies make it challenging to ensure a fully compatible cross-match is available for the mother. Guidelines exist from the Royal College of Obstetrics and Gynaecology, as well as the recently published British Society of Haematology Guidelines, on how to monitor and manage pregnant women with allo-antibodies. Techniques such as foetal middle cerebral artery monitoring as well as the ability to genotype foetal red cell DNA have contributed to the ability to risk-manage these women. The most clinically significant antibodies include Anti-D and Anti-c from the Rh group, as well as anti-K amongst others. The North Middlesex University Hospital, in London borough of Enfield, is responsible for over 5000 births per year. The hospital serves a multicultural area of London with a diverse ethnic population. In this abstract we outline the incidence of, and outcomes from, red cell alloantibody detection in our antenatal cohort. Over a five year period 149 women were found to have positive alloantibodies detected during routine antenatal screening, with 30 different alloantibodies identified. Of all antibodies detected 65.8% are known to be clinically significant. Some are associated with HDFN and others, such as anti-U pose a challenge in terms of finding compatible blood, with less than 0.1% of blood being compatible. From mothers with clinically significant antibodies, 28 neonates were found to have a positive direct antiglobulin test at delivery. 15 of these had elevated bilirubins at delivery, 2 required transfusion and one showed a delayed haemolytic reaction. The majority of these (10 cases) were associated with maternal anti-D. The remaining clinically significant alloantibodies in this cohort, causing HDN were anti-c, anti-E (x3) and anti-D+K. The management of clinically significant maternal red cell antibodies remains a critical area of transfusion practice. Around 1% of pregnant women are found to have clinically significant red cell antibodies and nationally the commonest antibody detected is anti-D. Our cohort differed from this, with a lower incidence of red cell antibodies detected antenatally, and the commonest antibody being anti-E. From our data anti-D remains the most relevant antibody regarding HDFN. Both of our neonatal cases that required exchange transfusion were associated with maternal anti-D Prompt recognition and close monitoring is key to avoiding harm to the foetus or neonate. In a mobile population, such as that seen in central London, ensuring mothers who require anti-D prophylaxis receive it, can be challenging. In our cohort we were unable to find outcome data on some mothers with clinically significant red cell antibodies. Whilst the patient population in Edmonton reflects a wide range of nationalities we see from this data that anti-D remains the most important antibody regarding neonatal health. Outcomes in our cohort were positive, but it remains important to manage expectant mothers in line with either RCOG or BSH guidelines.</span> [Conference abstract]</span>