Severe neonatal thrombocytopenia due to anti-HPA-4b alloantibodies: Third report described in a Caucasian mother.

BACKGROUND: Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) results from maternal platelet alloimmunization against paternal antigens inherited by the fetus, most often due to the Human Platelet Antigen (HPA)-1 system in Caucasians. We investigated in 2023, a 30-year-old Caucasian woman Gravida 2 Para 1 who gave birth at 35 weeks of gestation to a male (body weight 2210 g) without signs of bleeding. A severe thrombocytopenia (platelet count at 3 G/L) was discovered incidentally a few hours after delivery in the context of the management of a respiratory distress. The newborn recovered after one platelet concentrate transfusion and normalized his platelet count at Day 5. STUDY DESIGN AND METHODS: FNAIT investigation was performed according to guideline recommendations. Platelet genotyping was carried out by multiplex PCR. Maternal serological investigation included Monoclonal Antibody-specific Immobilization of Platelet Antigens method (MAIPA) and Luminex technology. RESULTS: Parental and newborn genotyping pointed out an HPA-4 incompatibility between the mother and the newborn and the father. Serological investigation revealed an anti-HPA-4b alloantibody confirming the diagnosis of neonatal alloimmune thrombocytopenia. CONCLUSION: We described the third case of anti-HPA-4b alloantibody discovered in a Caucasian mother. This case strengthens the need for reference laboratory to genotype a panel of HPA alleles reflecting local genetic population diversity and for crossmatch of maternal serum with fresh paternal platelets in clinical suspected cases of neonatal alloimmune thrombocytopenia.

Prenatal management of fetal anemia due to pyruvate kinase deficiency: A case report.

BACKGROUND: Pyruvate Kinase (PK) deficiency is the most common enzyme defect of glycolysis, leading to congenital hemolytic anemia, which can occur during the neonatal period. STUDY DESIGN AND METHODS: We report the prenatal management of fetal anemia related to PK deficiency in a family with a severe proband. RESULTS: The couple had a first child born with hydrops, whose PK deficiency was diagnosed at 18 months of life. He was treated with allogeneic bone marrow transplantation. The second child was free from disease. For the third pregnancy, the amniocentesis revealed a PK deficiency. Weekly ultrasound monitoring of the middle cerebral artery velocity allowed the detection of severe fetal anemia. Two intrauterine red blood cell transfusions (IUTs) were performed, raising the fetal hemoglobin from 6.6 to 14.5 g/dl at 28 weeks' gestation and from 8.9 to 15.3 g/dl at 31 weeks. A hematopoietic stem cell allograft was discussed prenatally but not chosen, as it would not have significantly changed the perinatal prognosis. The patient delivered a 2730 g girl at 37 weeks, with hemoglobin of 13.6 g/dl. The child presented with neonatal jaundice treated with phototherapy and received postnatal transfusions. DISCUSSION: When a proband is identified in a family, fetal investigation is warranted, to set up third-trimester ultrasound surveillance and perinatal management. In case of fetal severe anemia of unknown etiology, the workup on fetal blood sampling before IUT should comprise the search for erythrocytes enzymopathies, such as PK deficiency. IUTs allow safer full-term delivery in cases with PK deficiency.

Perinatal risk factors associated with severity of haemolytic disease of the foetus and newborn due to Rhc maternal-foetal incompatibility: A retrospective cohort study.

BACKGROUND AND OBJECTIVES: Anti-c is the third red blood cell antibody responsible for haemolytic disease of the foetus and newborn (HDFN) requiring intrauterine transfusion. We aimed to identify risk factors associated with HDFN and severe HDFN due to Rhc maternal-foetal incompatibility. MATERIALS AND METHODS: A retrospective cohort study was conducted in Paris and the surrounding area (France), between 2013 and 2015. We included mothers and their children managed by the National Reference Centre in Perinatal Hemobiology for alloimmunization and maternal-foetal incompatibility for the Rhc antigen (N = 121). We conducted bivariate analyses to assess a relationship between perinatal factors (e.g., titre and concentration of anti-c antibodies, direct antiglobulin test) and HDFN, its severity and duration. RESULTS: The incidence of HDFN was 30% (n = 36), including 11% of severe HDFN (n = 13). Seven percent (n = 9) of neonates received at least one transfusion during the first week and 21% (n = 26) after this period until 3 weeks of life. During pregnancy, a concentration ≥7.5 IU/ml and a titre ≥4 and above were associated with HDFN and severe HDFN (p < 0.05). At birth, the high intensity of the quantitative direct antiglobulin test was associated with HDFN and severe HDFN (p < 0.05). A concentration ≥15 IU/ml is the best factor (area under curve [AUC] = 0.78) in predicting HDFN, followed by a titre ≥8 (AUC = 0.76). CONCLUSION: Anti-c alloimmunization causes neonatal anaemia, which is often belated. Paediatricians have to be aware of these risk factors and organize prolonged monitoring of neonates.

POCT management of neonatal bilirubinemia ­ guidelines for an optimization of kernicterus monitoring / Intérêt de la bilirubinémie en néonatalogie : recommandations pour une utilisation coordonnée par le LBM de la biologie délocalisée et des tests rapides d'orientation diagnostique

In pediatrics, accurate measurement of total serum bilirubin (TSB) is of major importance for reliable diagnosis and appropriate management of neonatal jaundice. However, several studies evidenced poor comparability of results obtained with the different available methods either in central lab or in POCT, on serum, capillary blood or transcutaneous. This situation is partly due to the lack of Reference Materials, especially for high bilirubin concentrations but also on poor communication between central lab and neonatology unit. To progress on these issues, we have compiled some data from CNRHP to propose guidelines for choice, use and management of POCT devices and to help clinical laboratories to achieve a better answer to clinical needs with specific local constraints. The results from several CNRHP studies are presented: traceability to International System of Units, inter-laboratories comparability, POCT vs central labs comparisons with POCT CO-oximeter or photometer, integration of transcutaneous bilirubinometer. We propose, based on an analysis of devices advantages and issues, guidelines to help labs either to improve neonates monitoring in their local context; we distinguished the choices inside laboratory for a better harmonization of results compared to published thresholds and outside lab contexts, to organize a coordinated chain with POCT devices, with capillary and/or transcutaneous approaches.

En néonatalogie, la mesure précise de la bilirubinémie est essentielle pour le diagnostic et le suivi de l'ictère, en regard de seuils consensuels internationaux. Toutefois, une faible comparabilité des résultats est observée entre les laboratoires de biologie médicale (LBM) et avec les dispositifs délocalisés ou transcutanés. Cette situation est en partie due à des défauts de standardisation des méthodes, mais aussi à une coordination insuffisante entre les laboratoires et les unités de soins. L'objectif de ce travail est de progresser dans l'optimisation de la prise en charge des nouveau-nés en proposant des critères de choix et d'articulation des différentes réponses biologiques, EBM, EBMD et TROD, en fonction des besoins cliniques locaux et des moyens disponibles. Les résultats de plusieurs études ciblées sur la bilirubinémie néonatale sont présentés : raccordement au système international, harmonisation interlaboratoires, comparabilité EBMD-CNRHP d'un CO-oxymètre délocalisé en maternité, comparabilité EBMD-CNRHP d'un photomètre délocalisé en maternité, intégration d'un bilirubinomètre transcutané. Nous proposons ensuite, sur la base d'une analyse critique des différents types de dispositifs, des recommandations pour aider les LBM à améliorer la prise en charge des nouveau-nés dans leur contexte local, d'une part sur la mesure de la bilirubinémie néonatale au sein du LBM et d'autre part sur l'organisation d'une chaîne coordonnée EBM ­ EBMD ­ TROD en concertation avec les unités de soins.

Multidisciplinary management of anti-PP1Pk or anti-P alloimmunization during pregnancy: A new case with anti-P and a literature review.

BACKGROUND: Red blood cell alloimmunization is the first cause of fetal and neonatal anemia. Alloimmunizations with anti-PP1Pk or anti-P can cause recurrent miscarriages and hemolytic disease of the fetus and newborn in the 2nd and 3rd trimesters of pregnancy. We report on a pregnant patient immunized with anti-P and a history of recurrent miscarriages. CASE REPORT: This P2k (GLOB:-1; P1PK:-1,3) patient had a first pregnancy marked by a caesarean at 38 weeks of gestation (WG) for non-reassuring fetal heart rate. Then, she had three early spontaneous miscarriages. The fifth pregnancy began with a high titer of anti-P at 128. Early initiation of treatment with Intravenous Immunoglobulins (IVIg) and plasma exchanges (PE) starting at 5 WG permitted us to reduce the titer of anti-P below 32. A healthy infant was delivered by caesarean at 38 WG without anemia at birth and no exchange transfusion was required. DISCUSSION AND REVIEW OF THE LITERATURE: The P and Pk antigens are expressed on placental, trophoblastic, and embryonic cells. This explains why P1k (GLOB:-1; P1PK:1,3), P2k (GLOB:-1; P1PK:-1,3), or Tj(a-)/p (GLOB:-1; P1PK:-1,-3) patients are prone to recurrent abortions in the first trimester of pregnancy. A literature review demonstrated 87% (68/78) of miscarriages in p patients. However, publication biases are possible with the most severe cases being reported. CONCLUSION: Immunizations to P and PP1Pk antigens differ from others in their physiopathology and precocity. The association of PE and IVIg seems to be an effective treatment in the management of anti-PP1Pk or anti-P fetomaternal incompatibilities.

Effect of intravenous immunoglobulins to postpone the gestational age of first intrauterine transfusion in very severe red blood cell alloimmunization: A case-control study.

BACKGROUND: Early intrauterine transfusion (IUT) is associated with a higher risk of fetal loss. Our objective was to evaluate the efficiciency of intravenous immunoglobulins (IVIG) to postpone the gestational age at first IUT beyond 20 weeks of gestation (WG) compared to the previous pregnancy in case of very severe red blood cell (RBC) alloimmunization. STUDY DESIGN AND METHODS: Very severe RBC alloimmunization was defined by a high titer of antibodies and a previous pregnancy complicated by a first IUT before 24 WG and/or perinatal death directly related to alloimmunization. We performed a single-center case-control study. Cases and controls were patients respectively treated with weekly IVIG infusions started before 13 WG, and without. RESULTS: Twenty cases and 21 controls were included. Gestational age (GA) at first IUT was postponed after 20 WG in 18/20 (90 %) of patients treated with IVIG and in 15/21 (71 %) in the control group (p = 0.24). Compared to the previous pregnancy, the GA at first IUT was postponed by a median of 22 [+11; +49] days in the IVIG group and occurred in average 2 days earlier [-17 ; +12] in the non-treated group (p = 0.02). There was no difference between number of IUT and need for exchange-transfusion. IVIG treatment was associated with a significant decrease of antibodies' quantitation. CONCLUSION: In our series, IVIG tends to differ first IUT beyond 20 WG and have a significant effect in postponing the gestational age of the first IUT in patients with very severe RBC alloimmunization.

[Analytical and clinical guidelines on neonatal bilirubinemia]. / Recommandations analytiques et cliniques pour l'utilisation de la bilirubinémie en néonatalogie.

The SFBC-CNBH-CNRHP "Neonatal bilirubin" working group performed a biological and clinical study on bilirubin use in neonates for reliable diagnosis and appropriate management of neonatal jaundice. A brief report of a national survey on analytical and biological practices in France is shown. The guidelines of the French Society of Neonatology (SFN) founded the decision of phototherapy set up upon an accurate lab measurement of total serum bilirubin. An abacus is proposed with defined thresholds, as a function of neonate lifetime in hours. However, several studies evidenced poor comparability of results obtained with the different available methods. This situation is partly due to the lack of reference materials, especially for high bilirubin concentrations. Clinical consequences might be observed. We present in this paper the results of a national harmonization study to progress on this issue. Beyond the analytical aspects, the clinical consequences of harmonization defects were investigated. Finally, guidelines for clinical laboratories are proposed, to be locally adapted.

Reduced fetal movement during pregnancy: Is the Kleihauer-Betke test really useful?

INTRODUCTION: Reduced fetal movement (rFM) is a frequent cause of consultation during the pregnancy and can reveal feto-maternal hemorrhage (FMH) that is sometimes responsible of severe fetal anemia. Our primary objective was to evaluate the contribution of the KBT in case of rFM. Our secondary objective was to compare it with ultrasound examination including peak systolic velocity of the middle cerebral artery (MCA-PSV) to predict neonatal anemia. MATERIALS AND METHODS: We conducted a retrospective study from January 2016 to December 2017 at Armand-Trousseau Hospital in Paris. We analyzed all patients consulting for rFM from 18 to 41 weeks of gestation. We compared the performance of KBT and MCA-PSV to predict neonatal anemia (Hemoglobin at birth under 13.5 g/dL) and severe neonatal anemia (Hb < 10 g/dL). RESULTS: Among the 338 patients, 327 KBT (96.7%) were performed. KBT was found positive in three cases (0.9%). Only one neonate (0.3%) presented with severe anemia requiring a postnatal transfusion. MCA-PSV was performed in 166 cases (49.1%). KBT and MCA-PSV were significantly correlated with neonatal hemoglobin at birth. KBT was better than MCA-PSV to predict neonatal anemia, while MCA-PSV was better than KBT to predict moderate to severe anemia. The KBT and MCA-PSV Doppler had excellent sensitivity and predictive negative values (100%), but they had poor predictive positive values for severe neonatal anemia. CONCLUSION: In case of decreased fetal movement, we suggest performing fetal cerebral Doppler. MCA-PSV could suffice in first approach. KBT may be performed if there is suspicion of fetal anemia in order to confirm FMH.

Managing the Unusual Causes of Fetal Anemia.

BACKGROUND: Rare causes of fetal anemia requiring intrauterine transfusion (IUT) are challenging for fetal medicine specialists. OBJECTIVES: The aim of this study was to describe the perinatal patterns and prognosis in a consecutive series of fetuses transfused for fetal anemia of rare or unknown etiology, and to propose a protocol of investigation for fetal anemia of undetermined cause and for the management of subsequent pregnancies. METHOD: We conducted a retrospective descriptive study on fetuses transfused for severe anemia of rare or unknown etiology managed in our national referral center (Centre National de Référence d'Hémobiologie Périnatale) and born between 2010 and 2017. RESULTS: During the study period, 584 IUT were performed in 253 fetuses. Among those IUT, 23 (3.9%) were performed for a rare or unknown cause of anemia in 13 fetuses (5.1% of transfused fetuses). The median gestational age at diagnosis was 26 weeks of gestation (WG; range 21-33). Hemoglobin levels ranged from 1.6 to 9.1 g/dL (0.18-0.83 multiples of median) before the first IUT. The fetuses received between 1 and 6 IUT (39% received at least 2 IUT). The definitive etiologies for central anemia were: congenital syphilis, neonatal poikilocytosis, type II congenital dyserythropoietic anemia (CDA), and neonatal hemochromatosis. There was 1 case with suspected type I CDA and 1 with suspected Diamond-Blackfan anemia. There was 1 case of peripheral anemia, secondary to cerebral hemorrhages of different ages, related to a variant of the COL4A1 gene. In 6 fetuses corresponding to 4 mothers, no precise diagnosis was found despite a complete workup. In our series, there were 8 live births, 4 terminations of pregnancy, and 1 intrauterine fetal death. CONCLUSIONS: Fetal anemia of rare or unknown diagnosis represents 5% of all transfused fetuses in our cohort. Fetal and neonatal anemias can be recurrent in further pregnancies, with variable expressivity.

Effectiveness and costs of non-invasive foetal RHD genotyping in rhesus-D negative mothers: a French multicentric two-arm study of 850 women.

BACKGROUND: The determination of foetal Rhesus D (RHD) status allows appropriate use of IgRh prophylaxis by restricting its use to cases of RHD feto-maternal incompatibilities. There is a degree of uncertainty about the cost-effectiveness of foetal RHD determination, yet screening programs are being introduced into clinical practice in many countries. This paper evaluates the impact of non-invasive foetal Rhesus D (RHD) status determination on the costs of managing RHD-negative pregnant women and on the appropriate use of anti-D prophylaxis in a large sample of RHD-negative pregnant women using individual prospectively collected clinical and economic data. METHODS: A prospective two-armed trial of RHD negative pregnant women was performed in 11 French Obstetric Departments. Non-invasive foetal RHD genotyping was performed before 26 weeks' gestation in the experimental arm whereas the control arm participants received usual care. The costs associated with patient management in relation to their RHD negative status (biological tests, anti-D prophylaxis and visits) were calculated from inclusion to the end of the postpartum period. The costs of hospital admissions during pregnancy and delivery were also determined. RESULTS: A total of 949 patients were included by 11 centres between 2009 and 2012, and 850 completed follow-up, including medical and biological monitoring. Patients were separated into two groups: the genotyping group (n=515) and the control group (n=335). The cost of the genotyping was estimated at 140 euros per test. The total mean cost per patient was estimated at €3,259 (SD ± 1,120) and €3,004 (SD ± 1,004) in the genotyping and control groups respectively. The cost of delivery represented three quarters of the total cost in both groups. The performance of managing appropriately RHD negative anti-D prophylaxis was 88% in the genotyping group, versus 65% in the control group. Using the costs related to RHD status (biological tests, anti-D immunoglobulin injections and visits) the incremental cost-effectiveness ratio (ICER) was calculated to be €578 for each percentage gain in women receiving appropriate management. CONCLUSION: Early knowledge of the RHD status of the foetus using non-invasive foetal RHD genotyping significantly improved the management of RHD negative pregnancies with a small increase in cost. TRIAL REGISTRATION: Clinical trials registry- NCT00832962 -13 January 2009 - retrospectively registered.

[Critical care testing: SFBC recommendations in 2018]. / Biologie d'urgence : les recommandations 2018 de la SFBC.

The SFBC Working Group on critical care testing describes in this paper the SFBC recommendations for the determination of maximal turnaround times (TAT) for laboratory medicine examination in emergency conditions. The table presented in a previous paper was updated, taken into account the clinical situations, as well as the emergency response capabilities of the medical laboratory. These new French recommendations must to be based to each local situation in a clinical-biological context between the physicians and the specialist in Lab Medicine.

Clinical input of anti-D quantitation by continuous-flow analysis on autoanalyzer in the management of high-titer anti-D maternal alloimmunization.

BACKGROUND: In addition to titration by indirect antiglobulin test most widely used, anti-D quantitation by continuous-flow analysis (CFA) may be performed to assess severity of maternal immunization. Only five studies have reported its added value in the management of pregnancies complicated by anti-D immunization. STUDY DESIGN AND METHODS: A retrospective study of 74 severe anti-D-immunized pregnancies was conducted from January 1, 2013, to December 31, 2014, in the Trousseau Hospital in Paris (France). Concentration of maternal anti-D was measured by titration and by CFA two-stages method (2SM; total amount of anti-D) and one-stage method (1SM; high-affinity IgG1 anti-D). These biologic data were analyzed according to the severity of the hemolytic disease of the fetus and the newborn. RESULTS: The value of 5 IU anti-D/mL in maternal serum is validated as a threshold to trigger ultrasonographic and Doppler fetal close follow-up. A high 1SM/2SM ratio was associated with a higher risk of intrauterine transfusion (IUT). For pregnancies requiring IUT and without increasing titer, maternal 1SM anti-D concentration tends to correlate with the precocity of fetal anemia. In the "without-IUT" group 1SM and 2SM anti-D concentrations correlate significantly with cord bilirubin levels of the newborn at birth. CONCLUSION: Altogether our results underline the importance of anti-D quantitation by CFA to optimize the management of anti-D-alloimmunized pregnancies.

Accuracy of Middle Cerebral Artery Doppler Assessment between 34 and 37 Weeks in Fetuses with Red Cell Alloimmunization.

BACKGROUND: The Doppler measurement of middle cerebral artery peak systolic velocity (MCA-PSV) is considered the gold standard for the noninvasive detection of moderate to severe anemia. However, the accuracy of this test has not been evaluated so far, specifically beyond 34 weeks. OBJECTIVES: To assess the accuracy of MCA-PSV to detect moderate to severe fetal anemia and to identify risk factors associated with false-positive and false-negative MCA-PSV values after 34 weeks. STUDY DESIGN: We studied a retrospective cohort of 150 pregnant women with severe alloimmunization who delivered between 2010 and 2014 and correlated MCA-PSV and fetal or neonatal hemoglobin levels. RESULTS: Sensitivity to predict severe anemia was 69%, with a false-negative rate of 3.6%. When MCA Doppler assessment was normal, the identification of serosal effusions increased the detection rate of severe fetal anemia to 94%, with a false-negative rate of 0.8%. False-positive MCA-PSV measurements were more frequent in fetuses with 1 previous intrauterine transfusion (p = 0.0002), but were not associated with MCA resistance index, intrauterine growth restriction and fetal heart rate. CONCLUSIONS: Between 34 and 37 weeks, sensitivity of MCA-PSV Doppler assessment alone is 69% and increases to 94% when also considering signs of hydrops. False-positive MCA-PSV measurements are more frequent in case of former fetal transfusion.

[SFBC guidelines on critical care testing]. / Recommandations de la SFBC sur la biologie d'urgence.

SFBC working group on critical care testing describes in this paper guideline for the management of laboratory medicine examination process in emergency conditions. After a summary on French standards and regulations, the critical care testing perimeter and definitions of stat levels are presented in different contexts. The complete examination process is described. Guidelines are proposed for each step, to manage sub-process in a risk management approach. The following steps were studied: ordering (by specialties), sampling, transport, reception, analysis, validation and release. In summary, we proposed a list of examinations allowed to be prescribed in stat conditions with a short list and complementary tests as a function of clinical setting. These guidelines need to be adapted in clinicobiological contracts.

Clinical presentation and outcome of 20 fetuses with parvovirus B19 infection complicated by severe anemia and/or fetal hydrops.

AIM: The aim of this study was to assess the prognosis of parvovirus B19 infection with severely anemic and/or hydropic fetuses according to initial ultrasound and biological criteria. MATERIAL AND METHODS: Retrospective study of 20 cases of congenital parvovirus B19-proven infection (positive PCR) complicated by fetal anemia and/or hydrops was examined. Anemia was suspected on an elevated peak systolic velocity of the middle cerebral artery and was confirmed by fetal blood sampling. RESULTS: Survival rate was 70% (14/20) overall and 76% (13/17) for fetuses with one or more transfusions. When fetal effusion regressed after the transfusion, all 11 fetuses survived, and neonatal condition was favorable for all. Among the 14 live-born children, there was one neonatal death and one admission to the neonatal care unit with no major complications. CONCLUSION: Despite active management by transfusion in fetuses with parvovirus B19 infection, mortality remained substantial during the acute phase of anemia and fetal hydrops. Regression of effusion appears to be an important variable for prognosis. Non-anemic forms exist with isolated refractory ascites or pleural effusion. Maternal mirror syndrome appears to reflect the intensity and persistence of the fetal anemia.

RHD*DOL1 and RHD*DOL2 encode a partial D antigen and are in cis with the rare RHCE*ceBI allele in people of African descent.

BACKGROUND: Several studies showed in people of African descent the existence of a genetic linkage between RHD alleles encoding a variant D antigen and a given altered RHCE*ce allele. RHCE*ceBI is a rare allele encountered in people of African descent, that encodes a Hr- hr(S) - Rhce protein. Our study shows that RHCE*ceBI appears to be genetically linked to two very similar variant RHD alleles, RHD*DOL1 and RHD*DOL2, and demonstrates for the first time that DOL-2 is a partial D antigen. STUDY DESIGN AND METHODS: After finding out an individual with both RHCE*ceBI and RHD*DOL presumed to be in cis, we hypothesized a genetic linkage between those two genes. All individuals (n = 7) known to carry RHCE*ceBI in our laboratory, including the index case, were fully investigated at the serologic and molecular level. RESULTS: One individual with alloanti-D, being homozygous for RHCE*ceBI and RHD*DOL2, allowed us to confirm the genetic linkage between those two genes, as well as the partial D status of DOL-2. In the six RHCE*ceBI remaining individuals, three were found with RHD*DOL2 and 3 with RHD*DOL1, likely in cis. Three of them made an alloanti-D; one was DOL-1 and two were DOL-2. CONCLUSION: The rare RHCE*ceBI allele appears to be in cis either with RHD*DOL1 or with RHD*DOL2 in people of African descent. DOL-1 and DOL-2 must be considered as partial D antigens. We recommend a systematic search for RHD*DOL1 and RHD*DOL2 in people found to carry RHCE*ceBI and vice versa, especially in patients with sickle cell disease.

Management of very early fetal anemia resulting from red-cell alloimmunization before 20 weeks of gestation.

OBJECTIVE: To evaluate the results of management of very early fetal anemia (before 20 weeks of gestation) in cases of red-cell alloimmunization. METHODS: Retrospective study of the outcome of all in utero transfusions performed before 20 weeks of gestation and all pregnancies requiring an in utero transfusion before 20 weeks in our reference center from January 1990 through August 2011 in cases with severe alloimmunization. RESULTS: Twenty-five in utero transfusions were performed in 18 pregnancies in 16 patients during the study period. A vascular access was performed successfully in 22 of the 24 cases in which it was attempted. An intraperitoneal transfusion was necessary in two cases. Two in utero deaths attributable to the intravascular procedure occurred during attempts before 18 weeks of gestation and another, not associated with a transfusion, at 29 weeks. The overall survival rate was 83.3% (compared with 88.0% when the first in utero transfusion took place before 22 weeks). The risk of fetal loss for each transfusion was 8.0% before 20 weeks and 6.3% before 22 weeks. An intraperitoneal transfusion at 17 2/7 weeks allowed one fetus to survive until the first intravascular in utero transfusion could take place at 18 2/7 weeks. CONCLUSION: Fetal anemia before 20 weeks remains at high risk of lethal complications compared with later gestational ages. Technical difficulties in a vascular access are mainly encountered before 18 weeks of gestation. At an earlier gestational age, intraperitoneal transfusion may gain the days necessary to perform an intravascular transfusion more safely. LEVEL OF EVIDENCE: III.