Guía de manejo obstétrico y del recién nacido en madre aloinmunizada / Guidelines for the obstetric management of an alloimmune mother and her newborn / Guia de manejo obstétrico e neonatal em mães aloimunizadas

Resumen: La aloinmunización es una respuesta biológica frente a la exposición de antígenos no propios. La gestación, las transfusiones de hemocomponentes, los trasplantes de órganos sólidos y células hematopoyéticas, así como el consumo de drogas intravenosas exponen a las pacientes al desarrollo de aloanticuerpos antieritrocitarios. El hallazgo de los mismos debe cumplir con las instancias diagnósticas para identificar la probabilidad de estar asociados a enfermedad hemolítica feto neonatal (EHFN) y su oportuna derivación a policlínica de alto riesgo obstétrico (ARO) para su correcto seguimiento. Es fundamental que sean los laboratorios de inmunohematología de los servicios de hemoterapia y medicina transfusional los encargados de los estudios diagnósticos de aloinmunización eritrocitaria(1). En este sentido hemos elaborado esta guía con el objetivo de protocolizar de manera multidisciplinaria el manejo de las embarazadas aloinmunizadas y sus recién nacidos.

Abstract: Alloimmunization is the biological response to exposure to non-HLA antigens. Pregnancy, transfusion of blood components, solid organ and hematopoietic cell transplantation, as well as intravenous drug use expose patients to the development of anti-erythrocyte antibodies. When the latter are found, they must match diagnostic criteria to identify the potential association to hemolytic disease of the fetus and newborn (HDFN) and its timely referral to the high-risk obstetric risk polyclinic for due follow-up. It is of the essence for erythrocyte alloimmunization diagnostic tests to be carried out by the immunohematology laboratories of the Hemotherapy and Transfusional Medicine services. To that end, we have prepared these guidelines with the purpose of providing a multidisciplinary protocol for the handling of maternal alloimmunization and alloimmunization of the newborn.

Resumo: A aloimunização é uma resposta biológica à exposição a antígenos não próprios. A gravidez, as transfusões de hemocomponentes, os transplantes de órgãos sólidos e células hematopoiéticas, bem como o uso de drogas intravenosas expõem os pacientes ao desenvolvimento de anticorpos antieritrocitários. O achado destes deve obedecer a critérios diagnósticos para identificar a doença e a probabilidade de estarem associados a doença hemolítica feto neonatal (DHPN) e seu encaminhamento oportuno para uma unidade de alto risco obstétrico para acompanhamento adequado. É fundamental que os laboratórios de imuno-hematologia dos serviços de Hemoterapia e Medicina Transfusional se encarreguem dos estudos diagnósticos da aloimunização eritrocitária. Elaboramos este guia com o objetivo de estabelecer um protocolo multidisciplinar para o manejo de gestantes aloimunizadas e seus recém-nascidos.

Prenatal RHD genotyping in Croatia: preliminary results.

OBJECTIVES: Croatian Institute of Transfusion Medicine (CITM) implemented non-invasive fetal RHD genotyping as a request for targeted antenatal anti-D prophylaxis. The diagnostic performance of in-house RT-PCR method for fetal RHD genotyping and preliminary results are analyzed. MATERIALS AND METHODS: Evaluation included results of RHD genotyping for 205 RhD negative pregnant women, 12-36th week of gestation, whose samples were received in period between 2015 and 2020. QIAsymphony SP DSP Virus Midi Kit was used for cffDNA extraction on QIAsymphony SP platform (Qiagen, Germany). Fragments of RHD exons 7 and 10 and later exon 5 were RT-PCR amplified. As internal controls, amplification of SRY gene or RASSF1A fragment and ß-actin genes digested with BsTUI were used. RESULTS: We identified 70.72% (145/205) positive and 28.78% (59/205) negative fetal RHD genotypes. We had one inconclusive result (0.50%) due to the interference of maternal DNA with variant genotype RHD*09.02.00/01/*01N.01. When compared to newborns RhD phenotypes, no false negative and three false positive results (3/199, 1.50%) were observed. The test yielded 100% sensitivity and 95.08% specificity, while diagnostic accuracy was 98.48%. We were able to determine one case of fetal variant genotype RHD*04.04/*01N.01 inherited from the father. The negative and positive predictive test values were 100% and 97.86%, respectively. CONCLUSION: Automated cffDNA extraction and RT-PCR amplification of fetal RHD exons 5,7,10 and fragments of SRY, RASSF1A genes represents highly reliable system for determining fetal RHD status which enables targeted antenatal anti-D prophylaxis. To obtain high specificity of cffDNA extraction, strict and thoroughly cleaning procedures are required.

A survey of the current use of anti-D immunoprophylaxis and the incidence of haemolytic disease of the newborn in Italy.

INTRODUCTION: The Italian Society of Transfusion Medicine and Immunohaematology (SIMTI) carried out a survey on the current use of anti-D immunoprophylaxis (IP) in Italy, on its ways of use and on the impact that it has had on decreasing haemolytic disease of the newborn (HDN), due to maternal-foetal incompatibility for the D antigen. MATERIALS AND METHODS: The survey was carried out using a questionnaire prepared by the Working Group established for this purpose by the SIMTI. The questions were divided into five groups: the ways of carrying out IP, evaluation of foetal-maternal haemorrhage, serological tests after IP, the current incidence of HDN, and data on exchange transfusions. RESULTS: Data were obtained from 69 Transfusion Services (TS). Four of these give IP antenatally, whereas in the remaining cases IP is given after birth. Almost all the TS evaluate the amount of foetal-maternal haemorrhage in order to give additional doses of anti-D IgG, with the most widely used method being the Kleihauer-Betke test. Data were collected from 176,010 pregnancies: 18,639 were D-negative women, of whom 18,440 were not immunised. There were 136 cases of HDN with anti-D antibodies, and 39 of these required exchange transfusions (ET). Furthermore, there were 1,535 pregnant women with anti-A and/or anti-B IgG, which were clinically significant in 83 and required ET in 37. Finally, 40 women had antibodies, directly related to the pregnancy, against antigens other than D (in eight of these cases ET was necessary). CONCLUSIONS: The survey carried out by SIMTI was able to give a sufficiently full and accurate picture of current Italian practices concerning the use and ways of use of anti-D IP in pregnancy and the puerperum, as well as the incidence and characteristics of HDN. Furthermore, this survey was the basis for guidelines on the management of HDN, produced by SIMTI in collaboration with the Italian Society of Obstetricians and Gynaecologists.