Risk factors for RhD immunisation in a high coverage prevention programme of antenatal and postnatal RhIg: a nationwide cohort study.

OBJECTIVE: To evaluate which risk factors for RhD immunisation remain, despite adequate routine antenatal and postnatal RhIg prophylaxis (1000 IU RhIg) and additional administration of RhIg. The second objective was assessment of the current prevalence of RhD immunisations. DESIGN: Prospective cohort study. SETTING: The Netherlands. POPULATION: Two-year nationwide cohort of alloimmunised RhD-negative women. METHODS: RhD-negative women in their first RhD immunised pregnancy were included for risk factor analysis. We compared risk factors for RhD immunisation, occurring either in the previous non-immunised pregnancy or in the index pregnancy, with national population data derived from the Dutch perinatal registration (Perined). RESULTS: In the 2-year cohort, data from 193 women were eligible for analysis. Significant risk factors in women previously experiencing a pregnancy of an RhD-positive child (n = 113) were: caesarean section (CS) (OR 1.7, 95% CI 1.1-2.6), perinatal death (OR 3.5, 95% CI 1.1-10.9), gestational age >42 weeks (OR 6.1, 95% CI 2.2-16.6), postnatal bleeding (>1000 ml) (OR 2.0, 95% CI 1.1-3.6), manual removal of the placenta (MRP) (OR 4.3, 95% CI 2.0-9.3); these factors often occurred in combination. The miscarriage rate was significantly higher than in the Dutch population (35% versus 12.-5%, P < 0.001). CONCLUSION: Complicated deliveries, including cases of major bleeding and surgical interventions (CS, MRP), must be recognised as a risk factor, requiring estimation of fetomaternal haemorrhage volume and adjustment of RhIg dosing. The higher miscarriage rate suggests that existing RhIg protocols need adjustment or better compliance. TWEETABLE ABSTRACT: Complicated delivery (caesarean section, manual removal placenta, major bleeding) is the most valid risk factor for RhD immunization despite antenatal and postnatal RhIg.

Time points and risk factors for RhD immunizations after the implementation of targeted routine antenatal anti-D prophylaxis: A retrospective nationwide cohort study.

INTRODUCTION: Targeted routine antenatal anti-D prophylaxis was introduced to the national prophylaxis program in Finland in late 2013. The aim of this study was to assess the incidence, time-points, and risk factors for Rhesus D immunization after the implementation of routine antenatal anti-D prophylaxis, in all women in Finland with antenatal anti-D antibodies detected in 2014-2017. MATERIAL AND METHODS: In a nationwide population-based retrospective cohort study, the incidence, time-points, and risk factors of anti-D immunizations were analyzed. Information on antenatal screening was obtained from the Finnish Red Cross Blood Service database, and obstetric data from hospital records and the Finnish Medical Birth Register. RESULTS: The study included a total of 228 women (197 with complete data for all pregnancies). After the implementation of routine antenatal anti-D prophylaxis, the prevalence of pregnancies with anti-D antibodies decreased from 1.52% in 2014 to 0.88% in 2017, and the corresponding incidence of new immunizations decreased from 0.33% to 0.10%. Time-points for detection of new anti-D antibodies before and after 2014 were the first screening sample at 8-12 weeks of gestation in 52% vs 19%, the second sample at 24-26 weeks in 20% vs 50%, and the third screening at 36 weeks in 28% vs 32%. CONCLUSIONS: The incidence of new anti-D immunizations decreased as expected after the implementation of routine antenatal anti-D prophylaxis. True failures are rare and they mainly occur when the prophylaxis is not given appropriately, suggesting a need for constant education of healthcare professionals on the subject.

Red blood cell alloimmunisation after platelet transfusion (excluding ABO blood group system).

Red blood cell alloimmunisation after transfusion of red blood cell concentrates carries a risk for every recipient. This risk is particularly high for patients with conditions such as sickle cell disease. However, red blood cell alloimmunisation can also occur after platelet concentrate transfusion. All blood group systems other than ABO are affected, and there are several mechanisms responsible for this alloimmunisation. The practical implications of this are a need to match red blood cell concentrates in all alloimmunised patients and, in pregnant women, recongnition of the risk of developing haemolytic disease of the foetus and newborn. Several measures can be taken to prevent alloimmunisation: in the case of the D antigen, for example, anti-RhD immunoglobulins can be infused before transfusing platelet concentrates from an RhD-positive donor in a RhD-negative recipient.

Mitigation strategies for anti-D alloimmunization by platelet transfusion in haematopoietic stem cell transplant patients: a survey of NCCN® centres.

BACKGROUND AND OBJECTIVES: D-negative patients are at risk of developing an alloantibody to D (anti-D) if exposed to D during transfusion. The presence of anti-D can lead to haemolytic transfusion reactions and haemolytic disease of the newborn. Anti-D alloimmunization can also complicate allogeneic haematopoietic stem cell transplantation (HSCT) with haemolysis and increased transfusion requirements. The goal of this study was to determine whether cancer centres have transfusion practices intended to prevent anti-D alloimmunization with special attention in patients considered for HSCT. METHODS AND MATERIALS: To understand transfusion practices regarding D-positive platelets in D-negative patients with large transfusion needs, we surveyed the 28 cancer centres that are members of the National Comprehensive Cancer Network® (NCCN® ). RESULTS: Nineteen centres responded (68%). Most centres (79%) avoid transfusing D-positive platelets to RhD-negative patients when possible. Four centres (21%) avoid D-positive platelets only in D-negative women of childbearing age. If a D-negative patient receives a D-positive platelet transfusion, 53% of centres would consider treating with Rh immune globulin (RhIg) to prevent alloimmunization in women of childbearing age. Only one centre also gives RhIg to all D-negative patients who are HSCT candidates including adult men and women of no childbearing age. CONCLUSION: There is wide variation in platelet transfusion practices for supporting D-negative patients. The majority of centres do not have D-positive platelet transfusion policies focused on preventing anti-D alloimmunization specifically in patients undergoing HSCT. Multicentre, longitudinal studies are needed to understand the clinical implications of anti-D alloimmunization in HSCT patients.

Red cell alloimmunization: A 2020 update.

Management of maternal red cell alloimmunization has been revolutionized over the last 60 years. Advances in the prevention, screening, diagnosis, and treatment of alloimmune-induced fetal anemia make this condition an exemplar for contemporary practice in fetal therapy. Since survival is now an expectation, attention has turned to optimization of long-term outcomes following an alloimmunized pregnancy. In this review, the current management of red cell alloimmunization is described. Current research and future directions are discussed with particular emphasis on later life outcomes after alloimmune fetal anemia.

Anti-Rh alloimmunization after trauma resuscitation.

The AABB recently posted a bulletin (19-02) regarding their recommendations for the use of group O red blood cells (RBCs) during trauma. Though group O Rh(D)-negative RBC units are considered the 'safest', the demand of such units often exceeds the supply. Therefore, O Rh(D)-positive units are often used during the first parts of a massive transfusion protocol (MTP) or patients with particularly severe hemorrhage are switched over from O Rh(D)-negative to O Rh(D)-positive RBC units in order to preserve the O Rh(D)-negative supply. In light of these limitations, it is important to understand the risk of such policies to the patient. The reported risk of alloimmunization after exposure to Rh(D)-positive RBCs ranges widely from 3 to 70%. In response, we performed a retrospective review of 1,198 patients in our institution that had a MTP activation due to trauma. Of those patients, we focused on Rh(D)-negative patients that received at least 1 unit of Rh(D)-positive RBCs. Seventy-two patients met the criteria for inclusion, accounting for 6% of the total population. Of the 72 Rh(D)-negative patients, we identified 17% that formed new Rh group antibodies after exposure to Rh(D)-positive RBCS. All 10 of our alloimmunized patients (two of which were females of childbearing age) formed anti-D, while 3 patients also formed either anti-E or anti-C. Since this was a retrospective review, we did not perform repeated antibody screens for the entire study period, but did review all records for the entire period. We did note that we were more likely to detect an novel alloantibody if more antibody screens were performed during the patient's initial stay and during follow-up visits. We conclude that providing Rh(D) negative patients Rh(D) positive RBC units is not without risk and policies regarding such provisions should be carefully considered. As RBC shortages continue to be a part of daily practice, such issues may continue to be a challenge for the blood bank community.

Do chorionic villus samplings (CVS) or amniocenteses (AC) induce RhD immunisation? An evaluation of a large Danish cohort with no routine administration of anti-D after invasive prenatal testing.

OBJECTIVE: To evaluate the risk of inducing RhD immunisation in pregnancies of RhD-negative mothers with an RhD-positive fetus undergoing chorionic villus samplings (CVS) or amniocenteses (AC). DESIGN, SETTING AND POPULATION: Registry-based study in a Danish cohort which has not been given rhesus prophylaxis. METHODS: Data were retrieved from the Department of Clinical Immunology at Rigshospitalet. All RhD-negative women carrying an RhD-positive fetus with screen test results from weeks 8-12 and weeks 25-29 were linked to data from the Danish Fetal Medicine Database. Data were divided into cases where no invasive prenatal diagnostic procedure was performed, cases that had AC performed, and cases that had CVS performed. MAIN OUTCOME MEASURES: A comparison of the proportion of women who developed RhD immunisation between the two screen tests. RESULTS: The cohort consisted of 10 085 women: 9353 had no invasive procedures performed, 189 had AC and 543 had CVS performed. No women were immunised spontaneously or due to the procedure between the first and second screen test in the group with no procedure performed, or in the AC group. One woman was immunised in the CVS group. When comparing the proportion of women who was immunised in the CVS group with the no invasive test group a non-significant difference was found (P = 0.055). CONCLUSION: The RhD immunisation rate before gestational weeks 25-29 in RhD-negative women carrying an RhD-positive fetus is very low, even in women undergoing prenatal invasive testing without rhesus prophylaxis. TWEETABLE ABSTRACT: The RhD immunisation rate during pregnancy is very low even in women undergoing prenatal invasive testing.

Misinterpretation of blood group and antibody screen leading to serious errors in RhD immunoglobulin administration: A report on first two years of data from Serious Transfusion Incident Reporting program.

The Serious Transfusion Incident Reporting program (STIR) commenced haemovigilance in relation to RhD immunoglobulin (Ig) administration in 2015. During two years of reporting, 21 reports relating to RhD Ig administration were received. Thirty-three percent (7/21) were related to omission of RhD Ig, putting women at risk of RhD alloimmunisation and adverse consequences in future pregnancies. A recent case reported to STIR highlights poor communication and misinterpretation of pathology results leading to significant morbidity from haemolysis in the fetus. STIR makes recommendations related to education of staff and communication between clinical and laboratory staff to improve the safety of patient care.

Prehospital low-titer cold-stored whole blood: Philosophy for ubiquitous utilization of O-positive product for emergency use in hemorrhage due to injury.

The mortality from hemorrhage in trauma patients remains high. Early balanced resuscitation improves survival. These truths, balanced with the availability of local resources and our goals for positive regional impact, were the foundation for the development of our prehospital whole blood initiative-using low-titer cold-stored O RhD-positive whole blood. The main concern with use of RhD-positive blood is the potential development of isoimmunization in RhD-negative patients. We used our retrospective massive transfusion protocol (MTP) data to analyze the anticipated risk of this change in practice. In 30 months, of 124 total MTP patients, only one female of childbearing age that received an MTP was RhD-negative. With the risk of isoimmunization very low and the benefit of increased resources for the early administration of balanced resuscitation high, we determined that the utilization of low-titer cold-stored O RhD-positive whole blood would be safe and best serve our community.

No. 133-Prevention of Rh Alloimmunization.

OBJECTIVE: To provide guidelines on use of anti-D prophylaxis to optimize prevention of rhesus (Rh) alloimmunization in Canadian women. OUTCOMES: Decreased incidence of Rh alloimmunization and minimized practice variation with regards to immunoprophylaxis strategies. EVIDENCE: The Cochrane Library and MEDLINE were searched for English-language articles from 1968 to 200 I, relating to the prevention of Rh alloimmunization. Search terms included: Rho(D) immune globulin, Rh iso- or aile-immunization, anti-D, anti-Rh, WinRho, Rhogam, and pregnancy. Additional publications were identified from the bibliographies of these articles. All study types were reviewed. Randomized controlled trials were considered evidence of highest quality, followed by cohort studies. Key individual studies on which the principal recommendations are based are referenced. Supporting data for each recommendation is briefly summarized with evaluative comments and referenced. VALUES: The evidence collected was reviewed by the Maternal-Fetal Medicine and Genetics Committees of The Society of Obstetricians and Gynaecologists of Canada (SOGC) and quantified using the Evaluation of Evidence guidelines developed by the Canadian Task Force on the Periodic Health Exam. RECOMMENDATIONS: VALIDATION: These guidelines have been reviewed by the MaternalFetal Medicine Committee and the Genetics Committee, with input from the Rh Program of Nova Scotia. Final approval has been given by the Executive and Council of The Society of Obstetricians and Gynaecologists of Canada. SPONSORS: The Society of Obstetricians and Gynaecologists of Canada.

Laboratory management of perinatal patients with apparently "new" anti-D.

Despite the existence of long-standing, well-organized programs for Rh immune globulin (RhIG) prophylaxis, immune anti-D continues to be detected in the D­ perinatal population. Between 2006 and 2008, 91 prenatal patients, found to have a previously unidentified anti-D, were followed up with a survey to their treating physician and with additional serologic testing where possible. The physician survey requested pregnancy and RhIG history information, including recent or distant potential alloimmunizing events, and the physicians were asked their opinion on the likely cause for the anti-D. Based on survey responses, updated RhIG information, and results of follow-up serology, anti-D was determined to be attributable to previously unreported RhIG in 44 of 91 (48.3%) cases and to active immunization (immune anti-D) in 36 of 91 cases (39.6%). A probable cause for alloimmunization was reported in 14 of 52 (26.9%) returned surveys. Anti-D alloimmunization continues to occur in our prenatal population despite a comprehensive approach to RhIG therapy. Observations from this prospective patient management strategy include the need for improved application of guidelines for RhIG administration and improved quality of information provided to laboratories assessing RhIG eligibility. A laboratory process for prospective follow-up when unexpected anti-D is detected in pregnancy is recommended.

Prospective surveillance of D- recipients of D+ apheresis platelets: alloimmunization against D is not detected.

BACKGROUND: Recent retrospective studies indicate that D- recipients of D+ apheresis platelets (PLTs) are not alloimmunized to D. Our hospital policy is to offer RhIG to D- women of childbearing age who received D+ apheresis PLTs but not to other D- recipients of D+ apheresis PLTs. We instituted prospective surveillance of the D- recipients who were not given RhIG. STUDY DESIGN AND METHODS: All apheresis PLT recipients were prospectively entered into a database that recorded the patient's age, sex, diagnosis, D status, apheresis PLT transfusions, and antibody screen results from before and after PLT transfusions. Data are reported for PLTs transfused between October 16, 2012, and April 16, 2014, and antibody screens obtained through June 16, 2014. The analysis excludes neonates; women not more than 50 years of age; and patients who also received D+ red blood cells, received only D- PLTs, received RhIG, were previously alloimmunized to D, and did not have a follow-up antibody screen after the first D-incompatible apheresis PLT transfusion. RESULTS: A total of 158 of 1107 apheresis PLT recipients were D-. Seventy-nine were eligible for analysis based on the exclusion criteria listed above. None became alloimmunized to D during the observation interval. In 45 (57%) cases the last follow-up antibody screen was obtained at least 4 weeks after the first D-incompatible apheresis PLT transfusion. CONCLUSION: Prospective surveillance confirms prior retrospective observations that D- patients do not appear to risk D alloimmunization after receiving D+ apheresis PLTs.

[Platelet transfusion and immunization anti-Rh1: implication for immunoprophylaxis]. / Transfusion plaquettaire et iso-immunisation anti-Rh1: intérêt de la séroprévention.

Rhesus (Rh) antigens are not expressed on platelets but residual red cells carry the risk of anti-D iso-immunization in transfusion recipients of platelet concentrates (PC). The main theoretical risk associated with this reaction relates to female subjects due to potential obstetrical situations of maternal-foetal Rh incompatibility. Isogroup PC transfusion in this system is therefore advised. However, logistical constraints impose frequent Rh-incompatible transfusions that require the recommendation of anti-Rh immunoglobulin in a girl of childbearing age in this situation. This recommendation, already restricted to a group of patients deserves to be questioned over a decade after being issued. Data from published reports are difficult to interpret because of the heterogeneity of the few series (CP type, immune status, timing of biological tests) but the current techniques for preparing products and most common use of CP apheresis limited the risk of immunization. Moreover, platelet transfusions are particularly relevant to immunocompromised populations which, to what extent (heavy chemotherapy and/or hematopoietic stem cells recipients) seems to be protected from this risk. It is noteworthy that the clinical consequences that may be expected from such immunization are not reported. Although some authors emphasize significant isoimmunization rates (maximum 19%), the heterogeneous conditions and the lack of evidence of clinical consequence suggest evaluating the recommendations or revising them towards more targeted indications of seroprophylaxis.

Mirror syndrome in a Chinese hospital: diverse causes and maternal fetal features.

OBJECTIVE: To investigate the clinical characteristics of mirror syndrome. METHODS: Retrospective analysis of cases with mirror syndrome. Data of clinical manifestations, laboratory examinations, placental morphology, treatment and prognosis of these patients were obtained and studied. RESULTS: Five cases satisfying the inclusion criteria for mirror syndrome were identified from our hospital database. The incidence of the condition was 0.0154% in China. Mirror syndrome was associated with Rhesus isoimmunization, intrauterine parvovirus B19 infection, fetal neuroblastoma, fetal heart malformation and unknown cause respectively. Fetal symptoms were multi-hydrocele and fetal heart failure complicating fetal hydrops. All of the cases manifested maternal hydrops and hemodilution, the other most common symptoms included hypertension, proteinuria, hypoalbuminemia, anemia, thrombocytopenia and elevated uric acid levels. Fetal outcomes in this study were poor with a perinatal mortality rate of 100%. Placentomegaly was observed in most cases and placental morphology showed villous edema, increased intervillous fibrin deposition and one rare case of fetal adrenal neuroblastoma. Resolution of maternal symptoms was noted within 3-30 days after delivery. CONCLUSION: Mirror syndrome is associated with a substantially increased risk of fetal death and severe maternal complications. Early diagnosis of this condition during pregnancy is crucial for providing proper treatments and achieving better clinical outcomes.

Cholestasis in neonates with red cell alloimmune hemolytic disease: incidence, risk factors and outcome.

BACKGROUND: Etiology of cholestatic liver disease in neonates with hemolytic disease of the newborn (HDN) has been associated with iron overload due to intrauterine red cell transfusions (IUTs). Data on the incidence and severity of cholestasis in neonates with HDN are scarce, and little is known about pathogenesis, risk factors, neonatal management and outcome. OBJECTIVE: To evaluate incidence, risk factors, management and outcome of cholestasis in neonates with red cell alloimmune hemolytic disease. METHODS: All (near-) term neonates with HDN due to red cell alloimmunization admitted to our center between January 2000 and July 2010 were included in this observational study. Liver function tests (including conjugated bilirubin) were routinely performed in the neonatal period. We recorded the presence of cholestasis, investigated several potential risk factors and evaluated the management and outcome in affected neonates. RESULTS: A total of 313 infants with red cell alloimmune hemolytic disease treated with or without IUTs were included. The incidence of cholestasis was 13% (41/313). Two risk factors were independently associated with cholestasis: treatment with at least one IUT (OR 5.81, 95% CI 1.70-19.80, p = 0.005) and rhesus D type of alloimmunization (OR 4.66, 95% CI 1.05-20.57, p = 0.042). Additional diagnostic tests to investigate possible causes of cholestasis were all negative. In 5 infants (12%), supportive medical and nutritional therapy was started, and one neonate required iron chelation therapy. CONCLUSION: Cholestasis occurs in 13% of neonates with HDN due to red cell alloimmunization, and it is independently associated with IUT treatment and rhesus D type of alloimmunization.

Detection of fetomaternal hemorrhage.

The prevention of Rhesus D alloimmunization through Rh immune globulin (RhIg) administration is the major indication for the accurate detection and quantification of fetomaternal hemorrhage (FMH). In the setting of D incompatibility, D-positive fetal cells can sensitize the D-negative mother, resulting in maternal anti-D alloantibody production. These anti-D alloantibodies may lead to undesirable sequelae such as hemolytic disease of the newborn (HDN). Since the widespread adoption of FMH screening and RhIg immunoprophylaxis, the overall risk of Rh alloimmunization and infant mortality from HDN has substantially decreased. The rosette screen, the initial test of choice, is highly sensitive in qualitatively detecting 10 mL of fetal whole blood in the maternal circulation. As the screen is reliant on the presence of the D antigen to distinguish fetal from maternal cells, it cannot be used to detect FMH in D-positive mothers or in D-negative mothers carrying a D-negative fetus. The Kleihauer-Betke acid-elution test, the most widely used confirmatory test for quantifying FMH, relies on the principle that fetal RBCs contain mostly fetal hemoglobin (HbF), which is resistant to acid-elution whereas adult hemoglobin is acid-sensitive. Although the Kleihauer-Betke test is inexpensive and requires no special equipment, it lacks standardization and precision, and may not be accurate in conditions with elevated F-cells. Anti-HbF flow cytometry is a promising alternative, although its use is limited by equipment and staffing costs. Hematology analyzers with flow cytometry capabilities may be adapted for fetal cell detection, thus giving clinical laboratories a potentially attractive automated alternative for quantifying FMH.

[Management of feto-maternal red cell allo-immunizations]. / Prise en charge des allo-immunisations fœto-maternelles antiérythrocytaires.

Feto-maternal red cell alloimmunization is defined by the presence in a pregnant woman of alloantibodies directed against blood group antigens present on the red blood cells of the fetus and inherited from the father. It arises from the immune response to a first contact to these same antigens during a prior transfusion, transplant or pregnancy. The placental transfer and the fixation of the antibodies on the fetal red cells antigenic targets lead to a haemolysis in the fetus and the newborn. The resulting haemolytic disease can show different clinical forms, from a mild anaemia with neonatal hyperbilirubinemia to a major fetal damage with stillbirth caused by hydrops fetalis. The objective of management strategies of feto-maternal alloimmunization is to detect and monitor maternal alloimmunization and to appreciate the effects on the fetus or the newborn. Since a few years, some new non-invasive techniques of surveillance are used, for instance fetal RHD genotyping on maternal plasma and evaluation of fetal anaemia through velocimetry measurement of the blood flow in the middle cerebral artery. The need for a careful postnatal surveillance has to be emphasized due to the neonatal anaemia, which can be prolonged, and to the resurgence of cases of severe neonatal icteruses recently reported by the Académie de Médecine. The policy of prevention of anti-RH1 alloimmunization should also benefit from the evolution of biological techniques by allowing an improved targeting of concerned women.

Molecular RH blood group typing of serologically D-/CE+ donors: the use of a polymerase chain reaction-sequence-specific primer test kit with pooled samples.

The known presence of RHD blood group alleles in apparently D­ individuals who are positive for C or E antigens leads to an appropriate investigation for the RHD gene on the red blood cells (RBCs) of D­ blood donors, thus preventing their RBCs from immunizing D­ recipients. Ready-to-use polymerase chain reaction­sequence-specific primer (PCR-SSP) typing kits are available and allow single-sample results. The need to perform this testing on a large number of donors affiliated with the Transfusion Department of Udine (Northern Italy) led to the use of molecular genetic RH blood group typing with PCR-SSP test kits and DNA samples mixed in pools. From a population of 35,000 blood donors screened for D antigen by serologic typing, a total of 235 samples, distributed in pools of 5 DNA samples, were investigated. Positive results were reevaluated by opening the pools and retesting single samples. Validation of DNA-pool typing with commercial kits was done. Among 235 genotyped samples, 12 were found to be PCR positive (5.1%), exhibiting DEL genotype and RHD-CE-D hybrid alleles. Our data demonstrate that the use of a PCR-SSP commercial test kit with pooled samples is a helpful and valid method to correctly detect RHD alleles. As a consequence, we reclassified our donors as carriers of potentially immunogenic alleles.