Use of cffDNA to avoid administration of anti-D to pregnant women when the fetus is RhD-negative: implementation in the NHS.

OBJECTIVE: To determine whether a policy of offering cffDNA testing to all RhD-negative women at about 16 weeks' gestation to avoid anti-D administration when the fetus is RhD-negative could be implemented successfully in the NHS without additional funding. DESIGN: Prospectively planned observational service implementation pilot and notes audit. SETTING: Three maternity services in the South West of England. POPULATION: All RhD-negative women in a 6-month period. METHODS: Prospective, intervention, cross-sectional observational study, using pre-intervention data as controls. MAIN OUTCOME MEASURES: Proportion of suitable women who offered and accepted the test. Accuracy of the cffDNA result as assessed by cord blood group result. Fall in anti-D doses administered. RESULTS: 529 samples were received; three were unsuitable. The results were reported as RhD-positive (n = 278), RhD-negative (n = 185) or inconclusive, treat as positive (n = 63). Cord blood results were available in 502 (95%) and the only incorrect result was one case of a false positive (cffDNA reported as positive, cord blood negative - and so given anti-D unnecessarily). The notes audit showed that women who declined this service were correctly managed and that anti-D was not given when the fetus was predicted to be RhD-negative. The total use of anti-D doses fell by about 29% which equated to about 35% of RhD-negative women not receiving anti-D in their pregnancy unnecessarily. CONCLUSIONS: We recommend this service is extended to all UK NHS services.

Fetal blood grouping using cell free DNA - an improved service for RhD negative pregnant women.

Red cell alloimmunisation involves the transplacental movement of maternally derived red cell antibodies into the fetal circulation, causing red cell haemolysis, fetal anaemia and ultimately fetal death. Current standard UK practice is to prevent sensitisation to the D antigen by administering anti-D at about 28 weeks' gestation to all RhD negative pregnancies. The determination of fetal blood group by non-invasive cell free fetal DNA testing offers an improved and more efficient service to RhD negative pregnant women and avoids the potential iatrogenic harm associated with standard practice. It also has significantly improved the management of women with red cell alloimunisation to D and other antigens. This review summarises the past and future management of red cell alloimmunisation during pregnancy and the impact of ffDNA tests.

Impaired vascular permeability regulation caused by the VEGF165b splice variant in pre-eclampsia.

OBJECTIVE: Pre-eclampsia is diagnosed by hypertension and proteinuria, probably caused by endothelial dysfunction, resulting in symptoms including oedema, inflammation and altered metabolism. Vascular endothelial growth factor A (VEGF-A) is detected at higher concentrations in plasma from patients with pre-eclampsia than in plasma from normotensive pregnant patients when determined by radioimmunoassay. This study tested the hypothesis that circulating VEGF-A in pre-eclamptic plasma is biologically active in vivo, and aimed to identify specific isoforms responsible for this activity. DESIGN: Plasma from pre-eclamptic (n = 17) and normotensive (n = 10) pregnant women was perfused into Rana mesenteric microvessels, and the subsequent change in microvascular permeability was measured using a single-vessel perfusion micro-occlusion technique. RESULTS: Pre-eclamptic but not normotensive plasma resulted in a 5.25 ± 0.8-fold acute increase in vascular permeability (P = 0.0003). This increase could be blocked by the incubation of plasma with bevacizumab, an antibody to VEGF-A (n = 7; P = 0012), and by VEGF-A receptor inhibition by SU5416 at doses specific to VEGF-A receptor-1 (VEGFR1), but not by the VEGF-A receptor-2 inhibitor, ZM323881. Although VEGF(165) b levels were not significantly altered in the PET samples, the increase in permeability was also inhibited by incubation of pre-eclamptic plasma with an inhibitory monoclonal antibody specific for VEGF165b (n=6; P<0.01), or by the addition of placental growth factor 1 (PlGF-1; n = 3; P < 0.001). PlGF-1 was detected at lower concentrations in pre-eclamptic plasma than in normotensive plasma. CONCLUSIONS: These findings suggest that circulating VEGF-A levels in pre-eclampsia are biologically active because of a loss of repression of VEGFR1 signalling by PlGF-1, and VEGF165b may be involved in the increased vascular permeability of pre-eclampsia.

Pregenesys pre-eclampsia markers consensus meeting: What do we require from markers, risk assessment and model systems to tailor preventive strategies?

The Pregenesys Consensus Meeting held in Cambridge on 13 July 2009 was organized by the Pregenesys Consortium to review and critically discuss current knowledge regarding early markers of preeclampsia, to identify priorities and opportunities for future research, to consider issues that may need to be addressed in future recommendations and to highlight key issues in cost effectiveness and national policies concerning prediction and early screening for the risk of developing preeclampsia. This report summarizes the outcome of the Consensus Meeting and draws attention to issues for further investigation with specific regard to single versus multiple markers, early versus late risk identification, and the long-term effects on both maternal and perinatal health and the need to include these in any future cost-benefit assessment.

Increased free fetal DNA levels in early pregnancy plasma of women who subsequently develop preeclampsia and intrauterine growth restriction.

OBJECTIVE: To determine if maternal plasma ffDNA is increased early in pregnancies which subsequently develop preeclampsia (PE) and intrauterine growth restriction (IUGR). METHODS: Blood was obtained at 11-14 weeks and plasma stored. Among those who delivered a male infant and had a birth weight under the tenth centile and/or PE, we divided them into those who delivered before 35 weeks (9) and those who delivered after this gestation (15). A third group with uncomplicated pregnancies was used as controls (24). Real time-polymerase chain reaction (RT-PCR) was carried out to detect the multi-copy Y chromosome associated DSY14 gene. RESULTS: There were no differences between the ffDNA levels in the group delivered after 35 weeks and the control group (2.23ge/mL-1.61ge/mL p = 0.39). However, the levels of ffDNA at 11-14 weeks were statistically, significantly higher in patients that delivered before 35 weeks (4.34ge/mL-1.61ge/mL p = 0.0018). A logistic regression analysis shows that for every unit (1ge/mL) in which ffDNA increases, the likelihood of having PE or a fetus growing under the tenth centile delivered before 35 weeks increases by 1.67 times (CI 1.13-2.47). CONCLUSION: The concentration of ffDNA is significantly higher even during early pregnancy, in patients who subsequently develop PE and/or IUGR and are delivered before 35 weeks.

Management and outcome of pregnancies with parvovirus B19 infection over seven years in a tertiary fetal medicine unit.

OBJECTIVES: To determine rates of fetal anaemia and pregnancy outcome in susceptible pregnant women infected with human parvovirus B19 infection in a tertiary fetal medicine department over a 7-year period. Additional features enabling identification of fetuses that progress to severe anaemia were also investigated. METHODS: Forty-seven susceptible, pregnant women with confirmed parvovirus infection referred to a regional fetal medicine unit, over a 7-year period (1999-2006), were identified. Where possible maternal serum AFP measurements were obtained from second-trimester serum screening and the presence or absence of echogenic bowel noted. RESULTS: Of the 47 cases, one was excluded. Of the remaining 46 cases, 34 (74%) showed no signs of fetal anaemia and delivered at term. The remaining 12 (26%) showed signs of fetal anaemia. Eight of the 12 developed hydrops and underwent fetal blood sampling and transfusion (median pretransfusion Hb 3.6 g/dl). Seven of the 8 transfused fetuses were thrombocytopenic with a platelet count <150 x 10(9)/l, with 2 fetuses having platelet counts <50 x 10(9)/l. The median gestation age at transfusion was 22 weeks (range 18-27 weeks). The median number of weeks between seroconversion and transfusion was 6 (range 3-12). The signs of anaemia resolved after one transfusion in 5 of the 8 transfused fetuses and they subsequently delivered at term. There were 2 fetal deaths during or shortly after transfusion and one neonatal death following delivery at 28 weeks gestation due to severe pre-eclampsia, 5 days after successful transfusion. CONCLUSIONS: Following parvovirus seroconversion, the incidence of significant fetal anaemia requiring transfusion was 17%. Seroconversion after 21 weeks did not result in severe fetal anaemia. Significant anaemia requiring intervention did not occur 12 weeks after maternal seroconversion. We did not demonstrate a correlation with either maternal serum AFP or the presence of fetal echogenic bowel and the development of severe fetal anaemia. Because of the association between fetal anaemia and severe thrombocytopenia, it may be prudent to have compatible platelets available at the time of fetal blood sampling.

Non-invasive prenatal diagnosis: implications for antenatal diagnosis and management of high-risk pregnancies.

There has been a huge effort in the last 2-3 decades to develop non-invasive prenatal diagnosis to avoid the risks to the fetus caused by invasive procedures. Obtaining fetal nucleic material for molecular analysis without the need of invasive procedures has been a goal of prenatal diagnosis for many years; this is now been made possible by the use of non-cellular fetal nucleic acids circulating in maternal blood. The placenta is the primary source of these nucleic acids, raising the possibility that they could be a marker for pregnancy complications resulting from placental disease/dysfunction such as pre-eclampsia and fetal growth restriction. If so, these markers might be able to identify cases at risk, predict disease and/or its severity or allow early diagnosis. This has the potential to allow improvements in the management of complicated pregnancies.

Free fetal DNA in maternal plasma in anembryonic pregnancies: confirmation that the origin is the trophoblast.

OBJECTIVE: To test the hypothesis that free fetal DNA (ffDNA) circulating in maternal plasma originates mainly from the placenta we studied ffDNA levels in anembryonic pregnancies. METHODS: Maternal blood samples were collected from 15 normal first-trimester pregnancies in which fetal sex was subsequently determined and nine patients with a diagnosis of anembryonic gestation (AG). The Y chromosome DYS14 gene was quantified by real-time quantitative PCR (RT-PCR) for the determination of fetal sex in both plasma and chorionic tissue samples. Fetal sex in chorionic tissue samples was also determined using quantitative fluorescence PCR (QF-PCR). RESULTS: The correct sex result was obtained from maternal plasma in all. Four AG pregnancies were female (DYS14 negative) results. In five of the AG cases, the chorionic tissue was found to be male (by both QF-PCR and RT-PCR which agreed) and positive male signal was found in maternal plasma by RT-PCR. There was no statistical difference between median free fetal DNA concentration in plasma between the AG male cases (148.3 GE/mL) and controls (145.8 GE/mL). CONCLUSION: Since ffDNA levels are normal in pregnancies without a fetus, the data support the hypothesis that the trophoblastic cells are the major source ffDNA in maternal plasma.

Early detection of cell-free fetal DNA in maternal plasma.

OBJECTIVES: We aimed to establish the earliest gestational age at which fetal DNA in maternal plasma could be detected and whether this was reliable at 12-13 weeks' gestation. STUDY DESIGN: A prospective observational cohort study of 32 pregnancies either after IVF or before prenatal diagnosis by CVS. Maternal blood was taken and RT-PCR was carried out to detect the multi-copy Y chromosome associated DSY14 gene. The end point was gender as assessed at delivery or on karyotype. RESULTS: Y signal was obtained as early as 14 days post conception (4 weeks' gestation) and has a good prediction rate by 12 weeks' gestation. CONCLUSION: Free fetal DNA allows very early prediction of fetal sex in some cases and could be useful for clinical use for X-linked conditions by the end of the first trimester.

Management of fetal growth restriction.

Fetal growth restriction (FGR) is challenging because of the difficulties in reaching a definitive diagnosis of the cause and planning management. FGR is associated not only with a marked increased risk in perinatal mortality and morbidity but also with long-term outcome risks. Combinations of fetal biometry, amniotic fluid volume, heart rate patterns, arterial and venous Doppler, and biophysical variables allow a comprehensive fetal evaluation of FGR. However, no evidence supports that the use of cardiotocography or the biophysical profile improves perinatal outcome. Therefore, obstetricians aim to identify fetuses with early FGR so delivery can be planned according to gestational age and severity of the condition. The balance of risks and the need for the availability of services mean that the involvement of neonatologists in FGR management is vital. In this review, the focus is on the pathophysiology and management of FGR caused by placental diseases.

Detection of cell-free fetal DNA in maternal urine.

OBJECTIVE: To evaluate the presence of cell-free fetal DNA signals in maternal urine as a potential source of material for non-invasive prenatal diagnosis. STUDY DESIGN: Patients referred to the regional fetal medicine unit who underwent prenatal diagnosis by chorionic villus sampling (CVS) were asked to give blood and urine immediately before the procedure. Maternal blood and urine were centrifuged at 10,000 g for 10 min. Plasma (1 mL) and urine (1 mL) supernatant were transferred to a clean tube and centrifuged again. The plasma (0.8 mL) and urine (0.8 mL) supernatant were removed without disturbing the cell pellet and stored at - 80 degrees C. Following DNA extraction, each sample was tested for the presence of Y chromosome associated DYS14 gene using real-time polymerase chain reaction (PCR). The total amount (maternal and fetal) of DNA in each sample was estimated using a quantitative real-time PCR assay. RESULTS: Twenty patients were enrolled in the study. CVS was performed at a median gestational age of 13 weeks (range 11 + 5 - 14 + 1). There were 12 male and 8 female fetuses, as confirmed by karyotype. Y chromosome DNA was not detected in any of the 20 samples of maternal urine, including 12 of the 20 samples in which Y chromosome DNA was detected in maternal plasma (all of whom were subsequently confirmed to be carrying a male fetus). There was considerable variation in the amount of total free DNA detected in maternal urine. CONCLUSIONS: Cell-free fetal DNA either was not present or did not amplify in maternal urine.

Pregnancy outcomes in women with or without placental malaria infection.

OBJECTIVE: To assess delivery outcomes in women with placental malaria who presented at public hospitals in Kisumu, a holoendemic region in western Kenya. METHODS: A cross-sectional study using both histology and molecular biology was conducted with 90 consecutive pregnant women who presented at 3 hospitals during a 2-week period. Data collectors completed standardized questionnaires using each patient's hospital record and physical examination results, and registered birth indices such as weight, head circumference, and weight-head ratio. Malaria infection of the placenta was assessed using a molecular biology approach (for genomic differences among parasite species) as well as histology techniques. Of the 5 histologic classes of placental infection, class 1 corresponds to active infection and class 4 to past infection; class 2 and 3 to active chronic infection; and class 5 to uninfected individuals. Plasmodium species typing was determined by polymerase chain reaction amplification of the parasite's genome. RESULTS: In newborns at term, low birth weight was directly associated with classes 2 and 4 of placental infection (P = 0.053 and P = 0.003, respectively), and differences in birth weight remained significant between the 5 classes (P < 0.001) even after adjusting for parity and mother's age. Plasmodium falciparum was the only detected parasite. CONCLUSIONS: In Kisumu, infection with P. falciparum is an important cause of low birth weight and morbidity when it is associated with histologic classes 2 and 4 of placental infection. Moreover, polymerase chain reaction assays should be supported by ministries of health as an ancillary method of collecting data for malaria control during pregnancy and providing a baseline for future interventions.

Reactivity of T cells from women with antibodies to the human platelet antigen (HPA)-1a to peptides encompassing the HPA-1 polymorphism.

The human platelet antigen-1a (HPA-1a) is the most common alloantigenic target in fetal and neonatal alloimmune thrombocytopenia (NAIT). Treatment currently depends on the outcome in previous pregnancies. HPA-1 specific T cell responses were determined in 14 HPA-1a alloimmunized women during or after pregnancies affected by NAIT. Peripheral blood mononuclear cells were incubated with peptides encompassing the Leu33Pro polymorphism (residues 20-39 and 24-45 in both Leu33 (HPA-1a) and Pro33 (HPA-1b) forms) or control recall antigens in the presence of autologous sera and T cell proliferation was measured by (3)H-thymidine incorporation. Control antenatal and postpartum sera suppressed T cell proliferation and use of such sera was avoided. Most patients (86%) responded to the HPA-1a peptides with 64% also having weaker T cell proliferation to the HPA-1b peptides; 14% had no activity towards any peptide despite responding to control antigens. Administration of IVIG during pregnancy appeared to reduce T cell reactivity to HPA-1 peptides. Postnatal anti-HPA-1a T cell responses from women who had a severe history of NAIT (an intracranial haemorrhage in a previous fetus) were greater than those from women with a mild history. This assay may have the potential to predict disease severity if performed prior to or early in pregnancy.

Prenatal diagnosis of echogenic lung: evolution and outcome.

OBJECTIVES: Despite the feasibility of detecting lung lesions by antenatal ultrasound, there are problems in correlating the prenatal diagnosis with the final histology and in predicting the outcome. In order to better describe these factors, we reviewed the outcome of fetuses that had been diagnosed with echogenic lung in a referral fetal medicine unit. METHODS: We searched the database of a tertiary fetal medicine unit for all cases of fetal echogenic lung seen since 1994 and studied the maternal and neonatal records found. RESULTS: There were 48 cases of echogenic lung diagnosed at a median gestational age of 21 (range, 19-29) weeks, including 43 (90%) cases of congenital cystic adenomatoid malformation (CCAM) and 5 (10%) of pulmonary sequestration (PS). The evolution of the fetal abnormality after diagnosis was: in 22 (45.8%) cases the lesion disappeared; in 17 (35.5%) cases the lesion remained stable and six (12.5%) cases became severe. Three (6%) women underwent termination of pregnancy. The lesions were equally distributed between the two sides of the thorax. Mediastinal shift was associated with a threefold increase in the possibility of clinical deterioration (17% vs. 5%), and the disappearance of the lesion was twice as likely to occur when the lesion was classified as microcystic as when it was macrocystic (67% vs. 36%). Features of hydrops were found in 9 (21%) fetuses and in six (13%) cases progressed and resulted in intrauterine or neonatal death. Sixty-four percent of cases with lesions that disappeared during the pregnancy had an abnormal computed tomography (CT) scan, and the prenatal diagnosis correlated with histology in 36% of these cases. Of the cases in which the lesions remained stable, 70.5% had an abnormal CT scan and the prenatal diagnosis correlated with the histology in 67% of the cases. CONCLUSIONS: Prenatally diagnosed echogenic lung has a good prognosis in the absence of hydrops. The ability to correctly assess echogenic lung lesions and the need for surgery by prenatal ultrasound is limited.

Outcome of fetal pleural effusions treated by thoracoamniotic shunting.

OBJECTIVE: Fetal pleural effusions are uncommon, and treatment options for moderate or severe effusions include drainage and thoracoamniotic shunting. However, relatively few records of effusions treated by thoracoamniotic shunting are available in the literature, so our objective was to study the outcome after thoracoamniotic shunting in our unit. METHODS: We searched the database of our tertiary fetal medicine unit for all cases of fetal pleural effusion treated by thoracoamniotic shunting between 1997 and 2003 inclusive, and studied the maternal and neonatal records. RESULTS: Ninety-two cases of fetal pleural effusion were studied, of which 21 had undergone a thoracoamniotic shunt. Sixteen of these 21 fetuses (76%) had associated hydrops, of which seven (44%) survived and, of the five (24%) without associated hydrops, three (60%) survived. There were two procedure-related losses. No shunted cases were associated with abnormal karyotype or proven maternal infection, but it is probable that three cases had been caused by an underlying genetic syndrome. CONCLUSION: The survival of fetuses with severe pleural effusions after thoracoamniotic shunting in this study was 48%.

Comparison of different reference values of fetal blood flow velocity in the middle cerebral artery for predicting fetal anemia.

OBJECTIVES: To compare different normal reference ranges of fetal blood flow velocity in the middle cerebral artery for predicting fetal anemia. METHODS: Eight reference ranges of either middle cerebral artery peak or time-averaged mean velocities were compared using the area under the receiver-operating characteristics (ROC) curve for 113 fetal blood samples from 60 women at risk of fetal red blood cell alloimmunization. RESULTS: The areas under the ROC curves of the different ranges were not significantly different but there were marked differences in sensitivity (range, 7.14-91.78%) and specificity (range, 31.25-96.88%) with the currently used cut-offs. Except for Mari's range, the best theoretical cut-offs, defined as those having the best sensitivity with the best specificity, differed from those in current use, especially when using time-averaged mean velocity. CONCLUSIONS: Any of the previously reported reference ranges perform well in the non-invasive prediction of fetal anemia. However, with the exception of Mari's curve, the currently employed cut-offs for predicting fetal anemia should be changed, some of them markedly, in order to provide reliable support for clinical decisions.

Antenatal interventions for fetomaternal alloimmune thrombocytopenia.

BACKGROUND: Fetomaternal alloimmune thrombocytopenia occurs when the mother produces antibodies against a platelet alloantigen that the fetus has inherited from the father. A consequence of this can be a reduced number of platelets (thrombocytopenia) in the fetus, which can result in bleeding whilst in the womb or shortly after birth. In severe cases this bleeding may lead to long-lasting disability or death. Antenatal management of fetomaternal alloimmune thrombocytopenia centres on preventing severe thrombocytopenia in the fetus. Available management options include administration of intravenous immunoglobulins or corticosteroids to the mother or intrauterine transfusion of antigen compatible platelets to the fetus. All options are costly and need to be assessed in terms of potential risk and benefit to both the mother and an individual fetus. OBJECTIVES: To determine the optimal antenatal treatment of fetomaternal alloimmune thrombocytopenia to prevent fetal and neonatal haemorrhage and death. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register (February 2004), EMBASE (1980 to February 2004) and bibliographies of relevant publications and review articles. SELECTION CRITERIA: Randomised controlled studies comparing any intervention, including corticosteroids with no treatment, or comparing any two interventions. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed eligibility, trial quality and extracted data. MAIN RESULTS: One study met the inclusion criteria (54 pregnant women). This trial compared intravenous immunoglobulins plus corticosteroid (dexamethasone) with intravenous immunoglobulins alone. No significant differences were reported between the treatment and control groups, in any outcome measured: mean platelet count at birth (weighted mean difference (WMD) 14.10 x 10 9/l, 95% confidence interval (CI) -30.26 to 58.46), mean gestational age at birth (WMD -0.50 weeks, 95% CI -2.69 to 1.69), mean rise in platelet count from first to second fetal blood screen (WMD -3.50 x 10 9/l, 95% CI -24.62 to 17.62) and mean rise in platelet count from birth to first fetal blood screen (WMD 24.40 x 10 9/l (95% CI -14.17 to 62.97)). This trial had adequate methodological quality; however the method used to calculate sample size was inappropriate: therefore the power calculation was not sufficient to determine any significance in differences between the treatment groups. AUTHORS' CONCLUSIONS: There are insufficient data from randomised controlled trials to determine the optimal antenatal management of fetomaternal alloimmune thrombocytopenia. Future trials should consider the dose of intravenous immunoglobulins, the timing of initial treatment, monitoring of response to treatment by fetal blood sampling, laboratory measures to define pregnancies with a high risk of intercranial haemorrhage, management of non-responders and long-term follow up of children.

Fetal blood group genotyping from DNA from maternal plasma: an important advance in the management and prevention of haemolytic disease of the fetus and newborn.

The cloning of blood group genes and subsequent identification of the molecular bases of blood group polymorphisms has made it possible to predict blood group phenotypes from DNA with a reasonable degree of accuracy. The major application of this technology, which has now become the standard of care, is the determination of a fetal RHD genotype in women with anti-D, to assess whether the fetus is at risk of haemolytic disease of the fetus and newborn (HDFN). Initially, the procurement of fetal DNA required the invasive procedures of amniocentesis or chorionic villus sampling. Since the discovery of fetal DNA in maternal plasma in 1997, the technology of detecting an RHD gene in this very small quantity of fetal DNA has developed rapidly, so that non-invasive fetal D typing can now be provided as a diagnostic service for D-negative pregnant women with anti-D. Within a few years, it is probable that fetuses of all D-negative pregnant women will be tested for RHD, to establish whether the mother requires antenatal anti-D immunoglobulin prophylaxis.