Management of red blood cell alloimmunization in pregnancy.

The main cause of fetal anemia is maternal red blood cell alloimmunization (AI). The search of maternal antibodies by indirect antiglobulin test allows screening for AI during pregnancy. In case of AI, fetal genotyping (for Rh-D, Rh-c, Rh-E and Kell), quantification (for anti-rhesus antibodies) and antibody titration, as well as ultrasound monitoring, are performed. This surveillance aims at screening for severe anemia before hydrops fetalis occurs. Management of severe anemia is based on intrauterine transfusion (IUT) or labor induction depending on gestational age. After intrauterine transfusion, follow-up will focus on detecting recurrence of anemia and detecting fetal brain injury. With IUT, survival of fetuses with alloimmunization is greater than 90% but 4.8% of children with at least one IUT have neurodevelopmental impairment.

[Evaluation of conventional hemi nested PCR analysis for fetal RHD determination in maternal plasma]. / Evaluation de la détermination du statut Rhésus-D foetal sur plasma maternel par la technique d'hemi-nested PCR.

AIMS: The aim of our study was to evaluate the possibility of identifying the fetal RhD status in maternal plasma using conventional hemi nested PCR analysis. SUBJECTS AND METHODS: After informed written consent, 20 mL of peripheral blood were collected in 99 D-negative pregnant women either at an amniocentesis for prenatal diagnosis or at a prenatal checkup. Fetal DNA extracted from 400 microL of maternal plasma was analyzed by two different operators with a hemi-nested PCR extending an area of the RhD gene exon 10. The results were compared to the fetal RhD status obtained by PCR amniotic fluid analysis or blood analysis of newborns after delivery. The influence of mother's and baby's phenotype were also studied. RESULTS: Among the 99 D-negative pregnant women, all Caucasian, 47 were in their second trimester and 52 in their third trimester (mean: 27.20 weeks of gestation +/-8.25). Sixty-nine fetuses were D-positive and thirty D-negative. The sensitivity and specificity of our technique were respectively 100% and 86.7% and 15% of discordant results were observed between the two operators. Four false positives were observed. According to maternal phenotype, a fetal unexpressed RHD gene was suspected in only one case because of a particular fetal phenotype (ddCcEe). CONCLUSION: A conventional hemi nested PCR analysis of maternal plasma could be used for accurate fetal RhD status. However this procedure is difficult to apply for routine analysis because of the importance of anti-contamination measures required to obtain good results. Real time quantitative PCR analysis on fetal DNA is more suitable. Whatever the operating procedure used, polymorphism of RhD gene may follow in either false negative from presence of rearranged gene or false positive from occasional presence of a non functional RHD gene.

[Identification of alloantibodies associated with an autoantibody: profile of 2 quality control programs in French blood transfusion facilities]. / Identification d'allo-anticorps associés à un auto-anticorps: bilan de deux contrôles de qualité des établissements de transfusion sanguine français. Groupe Immunohématologie de la Société Française de Transfusion Sanguine.

The French Blood Transfusion Society working group Immunohaematology and the French Blood Transfusion Center of Lille performed two quality control exercises-96-01 and 97-02-in order to evaluate identification performances of alloantibodies associated with an autoantibody recognizing a high frequency antigen. Concerning control 96-01, 83 (75%) of the 110 blood transfusion centers participating at this exercise sent results. The alloantibody screening was correct for 78 of them (94%). Sixty-one (78%) blood transfusion centers correctly identified the specificities (anti-RH1 + anti-FY1). Concerning control 97-02, 82 (94%) of the 87 blood transfusion centers participating in this exercise sent results. The alloantibody screening was correct for 69 (88%) of them. Fifty-three blood transfusion centers (77%) correctly identified the specificities (anti-RH3 + anti-FY1). These exercises allowed us to confirm the main procedures used in routine for national scale testing. The analysis of the results has underlined the importance of these tests for assessing the quality of these examinations, and highlighted the means to be carried out in order to improve them.

[Fetal cells in the maternal blood: a step towards non-invasive prenatal diagnosis? Review of the literature]. / Cellules foetales dans le sang maternel: vers un diagnostic anténatal non invasif? Revue de la littérature.

Prenatal diagnosis of genetic abnormalities requires nucleated fetal cells which are currently obtained by invasive techniques such as amniocentesis, chorionic villus sampling and percutaneous umbilical blood sampling. Each of these entails a risk to the foetus and sometimes to the mother. Nucleated fetal cells have been reported to be present in maternal blood. Recovery of fetal cells from maternal blood would allow a noninvasive prenatal diagnosis. Their rarity (1 fetal cell for 10(6) to 10(8) maternal cells) presents a technical challenge. Due to the small number of fetal cells, sensitive analysis techniques such as PCR and FISH are necessary. Some degree of fetal cells enrichment in the maternal blood sample often precedes the analysis. Different techniques are used for the enrichment: discontinuous density gradient, magnetic activated cell sorting, fluorescence activated cell sorting, micromanipulator.... Several prenatal diagnosis have already been performed from maternal venous blood samples: diagnosis of gender, RhD blood genotype, Duchenne muscular dystrophy and hemoglobinopathy by PCR, diagnosis of gender and chromosome aneuploidy by FISH. Many teams are working on this subject. It is difficult to compare the studies because the techniques of enrichment and analysis vary. We review the different strategies chosen for prenatal diagnosis from maternal blood and discuss the results.

Is intrauterine exchange transfusion a safe procedure for management of fetal anaemia?

OBJECTIVE: To study modalities and complications of intrauterine exchange transfusion (IUET) for the management of severe fetal anaemia. STUDY DESIGN: Retrospective study of all IUET procedures performed between January 1999 and January 2012 at a regional centre. Characteristics of each procedure were studied to identify risk factors for complications. Survival rates according to the different aetiologies of anaemia were evaluated. RESULTS: In total, 225 IUET procedures were performed in 96 fetuses. Major indications were feto-maternal erythrocyte alloimmunization (n=80/96, 83.3%) and parvovirus B19 infection (n=13/96, 13.5%). Twenty-six percent of the fetuses (25/96) had hydrops fetalis before the first IUET. Intrauterine fetal death occurred after 2.7% (6/225) of procedures, premature rupture of the membranes occurred after 0.9% (2/225) of procedures, and emergency caesarean section was required after 3.6% (8/225) of procedures. Fetal bradycardia [odds ratio (OR) 37, 95% confidence interval (CI) 8.3-170; p<0.01] and gestational age up to 32 weeks (OR 3.67; 95% CI, 1.07-12.58; p=0.038] were significantly associated with complications after IUET. Complications occurred in 17.7% of pregnancies (17/96) and 7.5% of IUET procedures (17/225). The overall survival rate in the study cohort was 87.5% (84/96): 90% (72/80) in the alloimmunization group and 76.9% (10/13) in the parvovirus-infected group (NS). CONCLUSION: IUET has a higher complication rate than simple intrauterine transfusion, and should be performed by well-trained specialists.