Combined screening for open spina bifida at 11-13 weeks using fetal biparietal diameter and maternal serum markers

Research progress on ultrasound and molecular markers for prenatal diagnosis of neural tube defects

Neural tube defects (NTDs) are severe congenital anomalies that result from the failure of early neural tube closure during fetal neurogenesis. They are the most common and severe congenital malformations of the central nervous system. Identifying reliable prenatal diagnostic ultrasound and molecular markers that can predict NTDs is of paramount importance. Early diagnosis of NTDs allows embryonic treatment and prevention strategies, which are crucial for reducing the disability rate associated with these malformations, reducing the burden on individuals and on society. The purpose of this comprehensive review was to summarize the ultrasound biomarkers between 11 and 13 weeks of gestation and the molecular biomarkers used in the diagnosis of NTDs, providing additional insights into early screening for NTDs.

Proposal for standardized prenatal assessment of fetal open dysraphisms by the European reference network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies (ITHACA) and eUROGEN

Open dysraphisms, that is, myelomeningocele and myeloschisis, are rare diseases associated with a risk of severe disability, including lower limb motor and sensory deficiency, sphincter deficiency, and potential intellectual deficiency. Open dysraphism is diagnosed in Europe in 93.5% of cases. In case of suspicion of fetal open dysraphism, a detailed fetal morphologic assessment is required to confirm the diagnosis and exclude associated structural anomalies, as well as genetic assessment. In case of isolated fetal open dysraphism, assessment of prognosis is based on fetal imaging including the level of the lesion, the presence or not of a sac, the presence and nature of intra cranial anomalies, and the anatomical and functional evaluation of the lower extremities. Based on these biomarkers, a personalized prognosis as well as comprehensive information about prenatal management alternatives will allow parents to decide on further management options. Standardization of prenatal assessment is essential to compare outcomes with benchmark data and make assessment of surgical innovation possible. Herein, we propose a protocol for the standardized ultrasound assessment of fetuses with isolated open dysraphism.

Prenatal Zika virus infection has sex-specific effects on infant physical development and mother-infant social interactions

There is enormous variation in the extent to which fetal Zika virus (fZIKV) infection affects the developing brain. Despite the neural consequences of fZIKV infection observed in people and animal models, many open questions about the relationship between infection dynamics and fetal and infant development remain. To further understand how ZIKV affects the developing nervous system and the behavioral consequences of prenatal infection, we adopted a nonhuman primate model of fZIKV infection in which we inoculated pregnant rhesus macaques and their fetuses with ZIKV in the early second trimester of fetal development. We then tracked their health across gestation and characterized infant development across the first month of life. ZIKV-infected pregnant mothers had long periods of viremia and mild changes to their hematological profiles. ZIKV RNA concentrations, an indicator of infection magnitude, were higher in mothers whose fetuses were male, and the magnitude of ZIKV RNA in the mothers' plasma or amniotic fluid predicted infant outcomes. The magnitude of ZIKV RNA was negatively associated with infant growth across the first month of life, affecting males' growth more than females' growth, although for most metrics, both males and females evidenced slower growth rates as compared with control animals whose mothers were not ZIKV inoculated. Compared with control infants, fZIKV infants also spent more time with their mothers during the first month of life, a social behavior difference that may have long-lasting consequences on psychosocial development during childhood.

Teaching and training the total percutaneous fetoscopic myelomeningocele repair

Skin-over-biocellulose for Antenatal Fetoscopic Repair (SAFER) is a recently developed technique for fully percutaneous fetoscopic repair of myelomeningocele. The formation of a neo-dura mater triggered by the use of a biocellulose patch over the placode obviates the need of primary repair of fetal dura mater, and seems to further improve neurodevelopmental outcome. Insufflation of humidified carbon dioxide into the amniotic cavity requires proper training and a different equipment set from those used in the classic "under-water" fetoscopy. To shorten the learning curve of novice teams, we have developed a structured training course encompassing three critical steps: (1) visiting the proctor center, (2) selection of the first case, and (3) on-site training of the surgical team. Upon the site arrival, there will be: (1) theoretical lecture for all specialists involved in the fetal care, (2) simulation training, and (3) surgical proctoring. Proctor team can take over the surgery if the local team cannot complete. This training course has been successfully used in five different countries: Israel, Chile, Italy, USA and England and all local teams are already performing surgeries solo without any failures or maternal morbidity. Teaching new procedures in fetal medicine is challenging, because of the small number of candidate cases, and the direct relation of good outcomes and the number of cases operated. This proposed training modules may be adopted by other teams that want to embark on this type of novel minimally invasive treatment.

Maternal weight as an additional first trimester spina bifida screening marker

OBJECTIVE

To evaluate first trimester maternal weight as a spina bifida screening marker.

METHODS

Case-control study of spina bifida and unaffected pregnancies; cases were from national records and controls from women referred to prenatal screening centers in the Ukraine. The median and inter-quartile range of weight, body mass index (BMI) and the obesity rate (BMI ≥ 30 kg/m²) were compared. Discriminatory power was assessed by logistic regression. Gaussian modeling was used to predict the additional spina bifida detection when weight was included as a screening marker risk in addition to first trimester biparietal diameter (BPD) and serum α-fetoprotein (AFP).

RESULTS

There were 97 cases and 274 controls. The distribution of maternal weight was increased in cases by 3 kg, on average, about 5% (p < .05); BMI was increased about 8% (p < .005). Some 15% of cases were obese compared with 6.9% of controls (p < .02). In logistic regression including BMI and maternal age, 29% cases and 9.8% controls had high risk of spina bifida. Modeling predicted that incorporating weight would increase the detection rate compared with BPD and AFP alone by 3% and BMI would increase it by 4%.

CONCLUSION

Incorporating maternal weight into first trimester spina bifida screening protocols will increase detection.

Laboratory options for risk assessment of pregnancy pathologies

The most effective method of screening for chromosomal abnormalities and evaluating the risk of pregnancy pathologies in the first trimester is combined screening. The algorithm of screening is based on the combination of maternal age, measuring of the nuchal translucency and the fetal heart rate and analysis of the placental products of free ß-hCG and PAPP-A. For the screening of preeclampsia, placental growth factor (PlGF) is added. To distinguish between preeclampsia and other pathologies caused by placental dysfunction it is recommended to also extend the screening with selected immunological markers. We concluded that elevated biochemical and immunological markers can help to predict the threat of preeclampsia in the third trimester. Some markers can probably predict the development of particularly severe pathological conditions.

Spina bifida screening in the first trimester using ultrasound biparietal diameter measurement adjusted for crown-rump length or abdominal circumference

OBJECTIVE

Compare the performance of first trimester ultrasound biparietal diameter (BPD) screening for open spina bifida (OSB) when BPD is adjusted for crown-rump length (CRL) or abdominal circumference (AC).

METHODS

For 63 OSB and 24 265 unaffected pregnancies, BPD was expressed as multiple of the normal median (MoM) based on CRL and on AC, and as the ratio BPD/AC. Screening performance was assessed by the Mahalanobis distance, the observed detection rate with normal fifth and 10th percentile cut-offs and the area under the receiver-operator characteristic curve (AUC).

RESULTS

Mahalanobis distance for BPD MoM was considerably higher when based on AC than on CRL: 1.69 versus 1.14. Screening performance was also higher: using a fifth percentile cut-off, the detection rate was 59% compared with 41%; using a 10th percentile cut-off, the rates were 63% and 51%. Whilst the false-positives rates were slightly higher too-5.3% versus 5.1% and 10.8% versus 9.9%-the AUC was statistically significantly higher: 0.872 (95% CI, 0.816-0.928) compared with 0.735 (95% CI, 0.664-0.806). BPD/AC had intermediate performance.

CONCLUSION

The best results are obtained when AC, rather than CRL, is used to express BPD values in MoMs. First trimester OSB screening can detect half to two-thirds of cases.

Spina bifida in pregnancy: A review of the evidence for preconception, antenatal, intrapartum and postpartum care

Women with spina bifida in pregnancy require complex multi-disciplinary management. Most women have uncomplicated pregnancies; however, complications are more frequent than in 'low risk' pregnancies. Careful antenatal planning and management of the complications can optimise outcome. There are currently no guidelines on the management of pregnant women with spina bifida, but there is a growing body of evidence from case reports and series examining the antenatal and postnatal course of these women. In this review, we examine the available literature and provide a framework on the prenatal counselling, antenatal, intrapartum and postnatal management of pregnant women with spina bifida.

Down's Syndrome Screening in the First Trimester with Additional Serum Markers: Indian Parameters

Objective

To derive a risk calculation algorithm suitable for use in India when screening for Down's syndrome using four first-trimester maternal serum markers either alone or with ultrasound nuchal translucency (NT).

Methods

Stored maternal serum samples (- 20 °C) from 411 singleton unaffected pregnancies were retrieved and measured for pregnancy-associated plasma protein (PAPP-A), free β-human chorionic gonadotropin (hCG), placental growth factor and α-fetoprotein. Samples were taken at 10-13 weeks' gestation. Equations were derived to express marker levels in multiples of the gestation-specific normal median, adjusted for maternal weight. Gaussian model parameters were derived and compared with six published non-Indian studies; NT parameters were derived from 27,647 women screened in India. On the basis of the maternal age distribution in 64,473 Indian women screened in 2016-2017, the model was used to predict test performance.

Results

The model predicted a detection rate for a serum-only protocol of 80% for a 5% false-positive rate. Using a 1 in 250 at term Down's syndrome risk cut-off, the predicted detection rate was 78% and the false-positive rate was 4.1%. When NT was also included, the rates were 95% for 5% and 90% for 1.4%, respectively.

Conclusion

First-trimester screening using four serum markers only can be carried out in India. Performance is expected to be similar to the second-trimester Quad test and will also facilitate early screening for preeclampsia and open spina bifida. A protocol of NT plus the four serum markers enhances the performance compared with NT, PAPP-A and free β-hCG.

Impact on spina bifida screening of shifting prenatal Down syndrome maternal serum screening from the second trimester to the first

OBJECTIVES

Shifting screening for trisomy 21 to the first trimester has resulted in the loss of maternal serum alpha-fetoprotein screening for spina bifida. The aim of this study was to study the impact on open spina bifida prenatal screening.

STUDY DESIGN

We reviewed prenatally diagnosed cases of spina bifida over three years: 2009 (only second-trimester screening, MSM2T), 2010 (transient period) and 2011 (majority first-trimester screening, MSM1T). Cases were assigned to three groups based on maternal serum markers (MSM2T, MSM1T and 'not performed'). Gestational age at diagnosis of spina bifida was compared between these three groups and between the years 2009 and 2011.

RESULTS

Median gestational ages at diagnosis of the 742 spina bifida cases between the three groups were 22 weeks [18⁺⁶ -23], 22⁺¹  weeks [21⁺³ -23] and 21⁺⁴  weeks [14⁺¹ -23], respectively (P < 0.005). The diagnosis was made at 14-20 weeks in 34.7% for MSM2T group versus 8.5% for MSM1T (P < 0.001). Spina bifida diagnosis at 14-20 weeks declined from 38.8% in 2009 to 13.3% in 2011 (P < 0.001).

CONCLUSION

Loss of maternal serum alpha-fetoprotein had a tangible effect on the gestational age at diagnosis of spina bifida and resulted in a decrease of 25% of cases of spina bifida detected before 20 weeks. © 2017 John Wiley & Sons, Ltd.

Sonographic detection of central nervous system defects in the first trimester of pregnancy

The fetal central nervous system can already be examined in the first trimester of pregnancy. Acrania, alobar holoprosencephaly, cephaloceles, and spina bifida can confidently be diagnosed at that stage and should actively be looked for in every fetus undergoing first-trimester ultrasound. For some other conditions, such as vermian anomalies and agenesis of the corpus callosum, markers have been identified, but the diagnosis can only be confirmed in the second trimester of gestation. For these conditions, data on sensitivity and more importantly specificity and false positives are lacking, and one should therefore be aware not to falsely reassure or scare expecting parents based on first-trimester findings. This review summarizes the current knowledge of first-trimester neurosonography in the normal and abnormal fetus and gives an overview of which diseases can be diagnosed.

Cell-free DNA screening for fetal aneuploidy as a clinical service

Non-invasive prenatal testing (NIPT) through the analysis of cell free (cf)DNA is revolutionizing prenatal screening for fetal aneuploidy. Current methods used in clinical practice include shotgun massively parallel sequencing (s-MPS); targeted (t-MPS); and an approach that takes advantage of single nucleotide polymorphism (SNP) differences between mother and fetus. Efficacy of cfDNA testing for the common autosomal trisomies far exceeds that of conventional screening. Depending on the methodology used, reasons for discordancy between cfDNA results and fetal karyotype can include true fetal mosaicism, confined placental mosaicism, presence of a maternal karyotype abnormality, insufficient counting due to low fetal fraction, and a vanishing twin. Among the possible cfDNA strategies a Primary test has the highest performance but is expensive, while a Contingent cfDNA test can achieve high performance at a relatively low cost. Practicalities to be considered in the provision of testing include pretest counseling about the scope and accuracy of the testing, the interpretation of results when there is a low fetal fraction and follow-up studies for positive test results. The role of first trimester nuchal translucency measurement and conventional biochemical testing needs to be reassessed in the context of the use of cfDNA.

Prenatal diagnosis of open spina bifida in Emilia-Romagna

OBJECTIVE

To report recent data on the epidemiology of pregnancies affected by open spina bifida in the Emilia-Romagna region of Italy.

METHODS

All cases of open spina bifida diagnosed in the Emilia-Romagna region between 2001 and 2011 and reported to the IMER regional registry were included in the study group. The pregnancy outcome was retrospectively assessed.

RESULTS

In the study period out of 390,978 babies born in Emilia-Romagna 126 cases of open spina bifida were reported to the IMER registry, resulting in a global prevalence of 3.2 per 10,000 births. Prenatal diagnosis was achieved in the vast majority of these cases (105/126; 83.3%) and in a great proportion of those women (85/105; 80.9%) who opted for termination of pregnancy.

CONCLUSIONS

In a wide region of northern Italy where ultrasound anomaly scan is routinely offered to the general population, the vast majority of cases of open spina bifida are diagnosed antenatally and terminated electively.

SELDI-TOF-MS proteomic profiling of serum, urine, and amniotic fluid in neural tube defects

Neural tube defects (NTDs) are common birth defects, whose specific biomarkers are needed. The purpose of this pilot study is to determine whether protein profiling in NTD-mothers differ from normal controls using SELDI-TOF-MS. ProteinChip Biomarker System was used to evaluate 82 maternal serum samples, 78 urine samples and 76 amniotic fluid samples. The validity of classification tree was then challenged with a blind test set including another 20 NTD-mothers and 18 controls in serum samples, and another 19 NTD-mothers and 17 controls in urine samples, and another 20 NTD-mothers and 17 controls in amniotic fluid samples. Eight proteins detected in serum samples were up-regulated and four proteins were down-regulated in the NTD group. Four proteins detected in urine samples were up-regulated and one protein was down-regulated in the NTD group. Six proteins detected in amniotic fluid samples were up-regulated and one protein was down-regulated in the NTD group. The classification tree for serum samples separated NTDs from healthy individuals, achieving a sensitivity of 91% and a specificity of 97% in the training set, and achieving a sensitivity of 90% and a specificity of 97% and a positive predictive value of 95% in the test set. The classification tree for urine samples separated NTDs from controls, achieving a sensitivity of 95% and a specificity of 94% in the training set, and achieving a sensitivity of 89% and a specificity of 82% and a positive predictive value of 85% in the test set. The classification tree for amniotic fluid samples separated NTDs from controls, achieving a sensitivity of 93% and a specificity of 89% in the training set, and achieving a sensitivity of 90% and a specificity of 88% and a positive predictive value of 90% in the test set. These suggest that SELDI-TOF-MS is an additional method for NTDs pregnancies detection.

Detection of structural abnormalities in the first trimester using ultrasound

During the past 25 years, embryonic and early fetal ultrasound and diagnosis have increasingly gained attention in pregnancy care. Modern high-frequency ultrasound transducers make it possible to obtain detailed images of the early conceptus and its organs, and thus move part of the anatomy and anomaly scan from the second to the first trimester. Today, detection of embryonic and fetal structural abnormalities in the first trimester has frequently been reported. One has to distinguish between diagnosis during the early period until about 10 weeks when the embryo or early fetus is small and transvaginal ultrasound is applied, and diagnosis during the late period at the nuchal translucency screening, usually carried out using transabdominal ultrasound. Early first-trimester abnormalities are often diagnosed by chance on clinical indications, whereas late first-trimester diagnoses are the result of systematic screening using ultrasound markers.