Postnatal anti-D Prophylaxis Research Articles

External quality assessment of noninvasive fetal RHD genotyping.

Fetal RHD genotyping of cell-free maternal plasma DNA from RhD negative pregnant women can be used to guide targeted antenatal and postnatal anti-D prophylaxis for the prevention of RhD immunization. To assure the quality of clinical testing, we conducted an external quality assessment workshop with the participation of 31 laboratories. Aliquots of pooled maternal plasma from gestational week 25 were sent to each laboratory. One sample was fetal RHD positive, and a second sample was fetal RHD negative. A reporting scheme was supplied for data collection, including questions regarding the methodological setup, results and clinical recommendations. The samples were tested blindly. Different methodological approaches were used; 29 laboratories used qPCR and two laboratories used ddPCR, employing a total of eight different combinations of RHD exon targets. Fetal RHD genotyping was performed with no false-negative and no false-positive results. One inconclusive result was reported for the RHD positive sample. All clinical conclusions were satisfactory. This external quality assessment workshop demonstrates that despite the different approaches taken to perform the clinical assays, fetal RHD genotyping is a reliable laboratory assay to guide targeted use of Rh prophylaxis in a clinical setting.

Noninvasive fetal RHD genotyping to guide targeted anti-D prophylaxis-an external quality assessment workshop.

Fetal RHD genotyping of cell-free fetal DNA from RhD-negative pregnant women can be used to guide targeted antenatal and postnatal anti-D prophylaxis for the prevention of RhD immunization. To assure the quality of clinical testing, we conducted an external quality assessment workshop with the participation of 28 laboratories. Aliquots of pooled maternal plasma were sent to each laboratory. One sample was positive, and the second sample was negative for fetal RHD, verified by pre-workshop testing using quantitative real-time PCR (qPCR) analysis of RHD exons 4, 5, 7 and 10. Plasma samples were shipped at room temperature. A reporting scheme was supplied for data collection, including questions regarding the methodological setup, results and clinical recommendations. Different methodological approaches were used, all employing qPCR with a total of eight different combinations of RHD exon targets. The samples were tested blindly. Fetal RHD genotyping was performed with no false-negative and no false-positive results. One inconclusive result was reported for the RHD-positive sample, and four inconclusive results were reported for the RHD-negative sample. All clinical conclusions were satisfactory. This external quality assessment workshop demonstrates that despite the different approaches taken to perform the clinical assays, fetal RHD genotyping is a reliable laboratory assay to guide targeted use of Rh prophylaxis in a clinical setting.

A new biosensor for noninvasive determination of fetal RHD status in maternal blood of RhD negative pregnant women.

Prenatal detection of the fetal RHD status can be useful in the management of RhD incompatibility to identify fetuses at risk of hemolytic disease. Hemolytic disease causes morbidity and mortality of the fetus in the neonatal period. The routine use of antenatal and postnatal anti-D prophylaxis has reduced the incidence of hemolytic disease of the fetus and newborn. This study describe the detection of fetal RhD antigens in blood of RhD negative pregnant women using a nanopolymer coated electrochemical biosensor for medical diagnosis. Cell free fetal DNA in maternal plasma was also used to genotyping fetal RHD status using multiplex real-time PCR. Twenty-six RhD negative pregnant women in different gestational ages were included in the study. RhD positive fetal antibodies detected with a developed biosensor in maternal blood of RhD negative mothers. The electrochemical measurements were performed on a PalmSens potentiostat, and corundum ceramic based screen printed gold electrode combined with the reference Ag/AgCl electrode, and the auxiliary Au/Pd (98/2%) electrode. Fetal RHD genotyping performed using fluorescence-based multiplex real-time PCR exons 5 and 7 of the RHD gene. The fetal RHD status of 26 RhD negative cases were detected 21 as RhD positive and 5 as RhD negative with electrochemical biosensor. Fetal RHD status confirmed with extracted fetal DNA in maternal plasma using multiplex real-time PCR RHD genotyping and by serological test after delivery. The new method for fetal RhD detection in early pregnancy is useful and can be carry out rapidly in clinical diagnosis. Using automated biosensors are reproducible, quick and results can be generated within a few minutes compared to noninvasive fetal RHD genotyping from maternal plasma with real-time PCR-based techniques. We suggest the biosensor techniques could become an alternative part of fetal RHD genotyping from maternal plasma as a prenatal screening in the management of RhD incompatibility.

Determination of fetal RHD type in plasma of RhD negative pregnant women

Alloimmunization against the RhD antigen is the most common cause of hemolytic disease of the fetus and newborn. Antenatal anti-D prophylaxis in addition to postnatal anti-D prophylaxis reduces the number of RhD-immunizations compared to only postnatal administration. Cell-free fetal DNA released from the apoptotic trophoblastic placental cells into the maternal circulation can be used to determine the fetal RHD type in a blood sample from an RhD negative mother. Based on this typing, antenatal anti-D prophylaxis can be recommended only to RhD negative women carrying an RhD positive fetus, since only these women are at risk of developing anti-D. The objective was to establish and validate a method for non-invasive fetal RHD typing. The fetal RHD genotype was studied in 373 samples from RhD negative pregnant women (median gestational week 24). DNA extracted from plasma was analyzed for the presence/absence of RHD exon 7 and 10 in a real-time PCR. The RHD genotype of the fetus was compared with the serological RhD type of the newborn. In 234 samples, the fetal RHD test was positive and in 127 samples negative. There was one false positive and no false negative results. In 12 samples, the fetal RHD type could not be determined, in all of them due to a maternal RHD gene. This method gives a reliable detection of fetal RHD positivity in plasma from RhD negative pregnant women. Antenatal anti-D prophylaxis based on the predicted fetal RhD type will avoid unnecessary treatment of pregnant women carrying an RhD negative fetus.

Risk Factors for RhD Immunisation Despite Antenatal and Postnatal Anti-D Prophylaxis

Despite routine antenatal and postnatal administration of anti-D immunoglobulin (Ig) during pregnancy and delivery in a previous pregnancy, 0.1% to 0.3% of women are found to have Rhesus D (RhD) antibodies in their next pregnancy. The primary aim of this case-control study was to identify causative risk factors for rhesus D (RhD) immunization in the next pregnancy among women who had received adequate antenatal and postnatal anti-D prophylaxis in the previous pregnancy. A second aim was to evaluate the preventive effect of additional administration of anti-D Ig in such women with risk factors. Data obtained from the nationwide Dutch antenatal anti- D-prophylaxis program identified 42 new cases of RhD-immunized parae-1, detected with first-trimester screening, despite documented evidence of adequate antenatal and postnatal prophylaxis during the previous pregnancy. The controls were 339 parae-1 without red cell antibodies. Data on risk factors and other information was provided by the obstetric care worker and/or telephone interviews with the women. The primary study outcome measures were risk factors for RhD immunization. Multivariate analysis showed that statistically significant independent risk factors for RhD immunization were postmaturity (≥42 weeks of completed gestation) (odds ratio [OR], 3.07; 95% confidence interval [CI], 1.02-9.02), nonspontaneous delivery (assisted vaginal delivery or cesarean section) (OR, 2.23; 95% CI, 1.04-4.74), and age (OR, 0.89/yr; 95% CI, 0.80-0.98). Pregnancy-related red blood cell transfusion was almost significant; the OR was 3.51, with a 95% CI of 0.97 to 12.7. A condition related to increased feto-maternal hemorrhage and/or insufficient levels of anti-D Ig was observed in at least half of the failures of anti-D Ig prophylaxis. These findings provide direct evidence of causative risk factors for RhD immunization in the next pregnancy of women who had received adequate antenatal and postnatal anti-D prophylaxis in their previous pregnancy. The data show that RhD immunization may be further reduced by routine administration of extra anti-D Ig in these women.

Risk factors for RhD immunisation despite antenatal and postnatal anti-D prophylaxis

Risk factors for RhD immunisation despite antenatal and postnatal anti-D prophylaxis

Risk factors for RhD immunisation despite antenatal and postnatal anti-D prophylaxis.

ObjectiveTo identify risk factors for Rhesus D (RhD) immunisation in pregnancy, despite adequate antenatal and postnatal anti-D prophylaxis in the previous pregnancy. To generate evidence for improved primary prevention by extra administration of anti-D Ig in the presence of a risk factor.DesignCase–control study.SettingNation-wide evaluation of the Dutch antenatal anti-D-prophylaxis programme.PopulationCases: 42 RhD-immunised parae-1, recognised by first-trimester routine red cell antibody screening in their current pregnancy, who received antenatal and postnatal anti-D Ig prophylaxis (gifts of 1000 iu) in their first pregnancy. Controls: 339 parae-1 without red cell antibodies.MethodsData were collected via obstetric care workers and/or personal interviews with women.Main outcome measureSignificant risk factors for RhD immunisation in multivariate analysis.ResultsIndependent risk factors were non-spontaneous delivery (assisted vaginal delivery or caesarean section) (OR 2.23; 95% CI:1.04–4.74), postmaturity (≥42 weeks of completed gestation: OR 3.07; 95% CI:1.02–9.02), pregnancy-related red blood cell transfusion (OR 3.51; 95% CI:0.97–12.7 and age (OR 0.89/year; 95% CI:0.80–0.98). In 43% of cases, none of the categorical risk factors was present.ConclusionsIn at least half of the failures of anti-D Ig prophylaxis, a condition related to increased fetomaternal haemorrhage (FMH) and/or insufficient anti-D Ig levels was observed. Hence, RhD immunisation may be further reduced by strict compliance to guidelines concerning determination of FMH and accordingly adjusted anti-D Ig prophylaxis, or by routine administration of extra anti-D Ig after a non-spontaneous delivery and/or a complicated or prolonged third stage of labour.

Antenatal prophylaxis of Rh immunization with 250 micrograms anti-D immunoglobulin.

Anti-D immunoglobulin (250 micrograms) was given i.m. to 830 Rh-negative primigravidae and multigravidae round the 32nd to 34th week of gestation. The multigravidae had previously been treated with anti-D immunoglobulin post partum or after abortion and had been followed up serologically after 8 months. Five hundred and twenty-nine of the women delivered Rh-positive infants and received another injection of anti-D immunoglobulin (250 micrograms) within 72 hours of delivery. At the serological follow-up 8 months after delivery 2 women (0.4%) had weak anti-D antibodies by the papain technique. No anti-D could be detected in these 2 women 14 and 20 months, respectively, after delivery. In a previously performed postnatal clinical study with 250 micrograms anti-D immunoglobulin the failure rate was 1.6% (10 out of 645 women). Thus, antenatal prophylaxis significantly (p less than 0.05) reduced the incidence of Rh immunization. The haemoglobin and bilirubin levels in cord blood and capillary blood did not differ in the Rh-positive and Rh-negative infants. Three primiparae (0.2%) had anti-D antibodies at the time of the antenatal injection before delivery. Thus, the antenatal regimen of gestation did not give full protection from Rh immunization. It is suggested that an antenatal injection at the 28th week of gestation would have been more effective, as Rh sensitization during pregnancy has been reported to be more frequent from the 29th week of pregnancy. Since the introduction of postnatal anti-D prophylaxis the Rh immunization occurring during pregnancy accounts for most of the observed failures (2, 4, 5, 14, 20). The efficacy and safety of antenatal injection of anti-D immunoglobulin has therefore been investigated (5, 6, 7). At the Växjö Hospital in Sweden, where the incidence of anti-D antibodies was 1.6% (15), 250 micrograms of anti-D immunoglobulin were given at about 32-34 weeks of gestation from March, 1973, to December, 1977. The results are presented here.