Combination of "Markers" and the Consequent Importance of Fetal Abdominal Circumference in the First Trimester for Predicting Complications Specific to Monochorionic Twin Pregnancies

BACKGROUND

Multifetal pregnancies are considered high-risk pregnancies compared to singleton pregnancies. Monochorionic diamniotic (MCDA) twin pregnancies tend to have a more complicated intrauterine course than their dichorionic counterparts. The most common complications are twin-to-twin transfusion syndrome (TTTS), selective fetal growth restriction (sFGR), and unexplained intrauterine fetal demise (IUFD). Early recognition of pregnancies at risk of developing complications will be helpful for counselling the parents and preparing them for necessary interventions in case a complication arises.

OBJECTIVES

The aim of our study was to assess the role of discordant crown-rump length (dCRL), discordant nuchal translucency (dNT), and discordant abdominal circumference (dAC) measurements in isolation and in combination at the 11-13+6 weeks' scan in predicting the development of TTTS, sFGR, and IUFD.

METHODS

All MCDA twin pregnancies with structurally normal, both live fetuses at the 11-13+6 weeks' scan were followed up by FMF (Fetal Medicine Foundation)-certified operators for development of TTTS, sFGR, and single/double IUFD until delivery. Discordance of CRL, NT, and AC of more than or equal to 10% was considered a "marker," and its presence was correlated with the occurrence of specific antenatal complications, i.e., TTTS, sFGR, and single or double IUFD.

RESULTS

Combination of two markers predicted MCDA-related complications in the majority of cases (70.8% positive predictive value). Combination of dNT and dAC was the strongest predictor (80% positive predictive value).

CONCLUSIONS

In our population of MC twin pregnancies, dCRL, dNT, and dAC at the 11+0-13+6 weeks' scan, in isolation, had a low predictive value for antenatal complications, i.e., TTTS, sFGR, and single/double IUFD. However, the presence of at least two markers in the first trimester could predict complications in the majority of these pregnancies. The combination of dNT and dAC appears to be the best.

Prenatal and postnatal phenotype of a pathologic variant in the ATP6AP1 gene

INTRODUCTION

The ATP6AP1 gene encodes for ATPase H+ transporting protein. ATP6AP1 gene mutations are associated with congenital disorders of glycosylation (CDG) and can affect multiple organ system. Descriptions of postnatal phenotype include immunodeficiency, hepatopathy and cognitive impairment. No prenatal phenotype of these gene mutations has been described to date.

CASE

This is a description of the prenatal workup of an infant diagnosed with a X-linked ATP6AP1 gene mutation. First trimester ultrasound demonstrated a thickened nuchal translucency measured at 3.27 mm and dysmorphic spinal canal, corresponding to kyphoscoliosis finding postnatally. Findings from amniocentesis at 15 weeks included elevated amniotic fluid alpha-fetoprotein (AF-AFP) and positive acetylcholinesterase (AchE). Dilation of the aortic arch was seen on fetal echocardiogram at 20 weeks. Throughout the second trimester, a rim of fluid collection was seen under the skin covering the thoracic and lumbar fetal spine, consistent with a large Aplasia Cutis below the right scapula present at birth.

CONCLUSION

To our knowledge, this is the first description of prenatal phenotype of an X-linked ATP6AP1 gene mutation, and the association of this gene mutation with increased NT, elevated AF-AFP and AchE and Aplasia Cutis Congenita. This variant was submitted to ClinVar public database, submission ID: SUB6537411.

Genetic Examination for Fetuses with Increased Fetal Nuchal Translucency by Genomic Technology

This study aims to investigate the value of chromosomal microarray analysis (CMA) and whole exome sequencing (WES) in fetuses with increased nuchal translucency (defined as NT above the 95th centile for the crown-rump length). A total of 374 singleton pregnancies with gestational ages ranging from 11 to 13 + 6 weeks were investigated. Ultrasound displayed increased NT and no detectable structural malformations in these fetuses. Pregnancies were divided into 4 groups according to the NT values: 95th centile-3.4 mm (114 cases); 3.5-4.4 mm (150 cases); 4.5-5.4 mm (55 cases); and ≥5.5 mm (55 cases). The possible chromosomal anomalies were all analyzed by CMA first. Furthermore, 24 cases with increased NT but negative CMA results were investigated by WES, and the outcomes were followed up. Among all the 374 cases, causative genetic defects were detected in 100/374 (26.7%) of the cases along with 9 variants of unknown significance (VOUS) by CMA. CMA testing yielded 30 pathogenic variants (30/55), accounting for a detection rate of 54.5%, and 1 VOUS in the group of NT ≥5.5 mm, indicating the highest detection rate in the 4 groups. The 24 cases of the CMA negative sub-cohort with WES analysis further yielded 2 VOUS and 3 likely pathogenic variants, including 2 dominant de novo mutations in SOS1 and ECE1 and 1 recessive inherited compound heterozygous mutation in PIGN, which are associated with cardiac defects. All 3 cases opted for termination of pregnancy (TOP). In addition, 2 cases with increased NT were negative by both CMA and WES analysis, and fetal demise occurred. In conclusion, for the investigation of fetuses with increased NT exome sequencing is suggested to be considered in cases with negative CMA findings. However, appropriate genetic counseling should be given to optimizing its utilization in prenatal diagnosis.

Relationship between first trimester nuchal septations and chromosomal anomalies

OBJECTIVES

This study aimed to evaluate the association of nuchal septations with chromosomal anomalies during the first trimester of pregnancy.

METHODS

A total of 281 patients who were diagnosed to have elevated nuchal translucency (NT > 3 mm) or nuchal septations during the first trimester from Jan. 2014 to Dec. 2016 were included. These patients were divided into three groups: 1) patients with NT thickness between 3 and 5 mm and without nuchal septations (NT 3-5 mm group, n = 124), 2) patients with NT thickness > 5 mm and without nuchal septations (NT > 5 mm group, n = 96), and 3) patients with nuchal septations (NS group, n = 61).

RESULTS

The rate of chromosomal abnormalities was significantly higher for patients in NS group compared to those in the NT 3-5 mm group (P < .01) and NT > 5 mm group (P < .01). After controlling for maternal age, maternal BMI, ethnicity and crown-rump length, nuchal septations were reported to be significantly associated with a higher risk of chromosomal anomalies compared with NT 3-5 mm (OR = 4.97; 95% CI: 2.76-10.77; P < .01) and NT > 5 mm (OR = 3.82; 95% CI: 1.87-7.21; P < .01) (P < .01).

CONCLUSIONS

Measurement of nuchal septations during the first trimester of pregnancy proves to be a useful ultrasound prognostic indicator of chromosomal anomalies.

Pregnancy outcome in foetuses with increased nuchal translucency - 10-years' experience in a prenatal medical practice

This retrospective study describes pregnancy outcome for foetuses with increased nuchal translucency (NT) in relation to the degree of increase in a local specialised medical practice. Data from 7352 first trimester pregnancies examined by a single observer between 10/07 and 07/17 were screened. Three hundred and ninety-three foetuses (5.3%) that had an increased NT ≥ 95th percentile and available pregnancy outcome were identified. For this population, the frequencies of chromosomal abnormality, foetal malformation, intrauterine death (IUD) and termination of pregnancy (TOP) were determined in relation to the degree of NT thickness. Favourable pregnancy outcome decreased from 77.8% (lowest NT group, 95th percentile-3.5 mm) to 5% (highest NT ≥ 6.5 mm), whereas chromosomal abnormalities rose from 18.1% to 70%. An abnormal karyotype occurred in 39.2% of foetuses with increased NT. In euploid foetuses, cardiac defects were the most common structural abnormalities. The data largely matches with earlier studies conducted in large hospital-based settings. However, a rather high proportion of foetuses with abnormal karyotype was observed.IMPACT STATEMENTWhat is already known on this subject? Increased NT is associated with chromosomal abnormalities as well as an adverse perinatal outcome also in foetuses with a normal karyotype. The prevalence of an adverse outcome increases with NT thickness. These studies were conducted more than 10 years ago mainly in academic settings.What do the results of this study add? This study describes pregnancy outcome of a population of foetuses with increased NT that were examined in a medical practice by a single observer over a period of 10 years with state of the art ultrasound equipment. We observed a relatively large proportion of foetuses with abnormal karyotype. In euploid foetuses, increased NT was associated with a wide range of foetal malformations and genetic syndromes.What are the implications of these findings for clinical practice and/or further research? Even mildly increased NT thickness is associated with an adverse pregnancy outcome, underlining the importance of thorough ultrasound examinations. Specialised prenatal medical practices can provide state-of the art technology and provide improve parental counselling.

Increased nuchal translucency and pregnancy outcomes: experience of Başkent University Ankara Hospital

Objective:

First trimester nuchal translucency (NT) measurement is considered to be an important tool in antenatal follow-up. This study aimed to evaluate the outcomes of pregnancies with increased NT at Başkent University Ankara Hospital between 2004 and 2016.

Materials and Methods:

Patients with NT measurements ≥1.5 multiples of median (MoM) were divided into two groups; group I included increased NT cases without fetal anomalies (either abnormal fetal karyotype or congenital structural anomalies) or loss (intrauterine fetal death), and group II included increased NT cases with fetal anomalies or loss. The groups were compared with each other with respect to maternal demographic features and NT measurements.

Results:

Karyotype analyses were normal in 73.1% of cases with increased NT (57/78). Among those, 21.1% (12/57) had structural anomalies, and to specify, 9.6% (5/52 over 18 weeks) had cardiac anomalies. Although maternal demographic features did not differ significantly, NT measurements, both as millimeters and MoM, were significantly higher in group II (p<0.05). According to the receiver operating characteristic (ROC) curves, the optimal cut-off values for NT measurements for predicting fetal anomalies or loss were 3.05 mm and 2.02 MoM. NT measurement >7 millimeters or NT MoM >4.27 resulted in poor fetal outcomes without exception.

Conclusion:

Higher NT measurements indicate poorer pregnancy outcomes. Our study indicates that fetal echocardiography must be considered for all cases with increased NT.

Value of increased nuchal translucency in the era of noninvasive prenatal testing with cell-free DNA

OBJECTIVE

To assess the value of increased nuchal translucency (NT) at first-trimester screening (FTS) despite the superiority of noninvasive prenatal testing with cell-free DNA (cfDNA) for the detection of fetal aneuploidies.

METHODS

Retrospective analysis of all FTS data from 2005 to 2015 in our department. Only cases with increased NT and euploid karyotype were considered eligible for inclusion. Abnormal findings, diagnostic work-up, and perinatal outcomes were assessed.

RESULTS

Of 18 084 FTS results, 460 (2.5%) showed increased fetal NT, of which 242 (52.6%) underwent invasive karyotyping and 179 (74.0%) had an aneuploidy. Of the remaining 63 cases, 61 (96.8%) showed an additional sonographic finding at FTS and25 (78.1%) had a major anomaly at the second trimester organ scan. The outcome was termination of pregnancy in 28 (44.4%) cases, fetal demise in 5 (7.9%), delivery of an infant with malformation in 21 (33.3%), and delivery of a healthy infant in 7 (11.1%) cases.

CONCLUSION

All cases with increased NT would have been detected by cfDNA or by a major sonographic anomaly not later than the second trimester. Routine use of cfDNA, a basic sonogram, and an organ scan could reduce unnecessary work-up and anxiety.

Fetal nuchal translucency: is there an association with birthweight and neonatal wellbeing?

Objective

To evaluate the relationship between nuchal translucency (NT) values with birthweight and the wellbeing of the newborn.

Materials and Methods

This retrospective cohort study that included 508 patients made use of data on healthy full-term, singleton, live birth newborns in a university hospital between 2016 and 2018. The relationship between the NT multiple of the median (MoM) value and maternal body mass index, birthweight, sex, need for neonatal intensive care unit (NICU), and APGAR scores was evaluated. Similarly, the relationship between birthweight and NT MoM, and biochemical data in the first trimester was also evaluated.

Results

There was a positive correlation between NT and birthweight (p<0.001). The need for NICU admission increased (p=0.001), and APGAR 1st minute scores decreased (p=0.001) with increasing NT, and APGAR 5th minute scores remained unchanged (p=0.057).

Conclusion

The present study identified a positive correlation between first trimester NT and birthweight, and a negative correlation with the wellbeing of the neonate.

Cleft Palate with or without Cleft Lip: The Role of Retronasal Triangle View and Maxillary Gap at 11-14 Weeks

OBJECTIVE

To evaluate the presence of maxillary gap (MG) and abnormal retronasal triangle (RT) as markers of cleft palate (CP) with and without cleft lip in the first trimester and to assess their association with the type of orofacial cleft (OC).

METHODS

The RT and the mid-sagittal view of the face were evaluated retrospectively by two operators in 26 fetuses with OC and in 80 normal controls to detect abnormal RT and/or MG. The agreement between operators was calculated.

RESULTS

Amongst the 26 fetuses, there were 15 cases of bilateral, 6 cases of unilateral, and 4 cases of median cleft lip and palate, and 1 case of CP alone. The MG was observed in 18 cases by operator 1 and in 17 cases by operator 2; an abnormal RT was detected in 21 cases by operator 1 and in 22 cases by operator 2. Great agreement between operators was obtained. In controls, MG or abnormal RT was suspected in 6 and 2-4% of cases, respectively.

CONCLUSIONS

RT seems to be more sensitive compared to MG; however, the latter showed an additional diagnostic ability when the secondary palate was involved. Both approaches in combination could be useful in detecting OC in the first trimester.

Performance of Common Down Syndrome Screening Methods Used in India with Construction of an Indian Normogram for Nuchal Translucency/Crown-Rump Length Measurements in 14,337 Subjects

Background/Purpose of Study

Sonologists often lack access to the Fetal Medicine Foundation Down syndrome risk calculation software or cannot offer the combined test for aneuploidy screening because of resource constraints. Instead, sonologists use nuchal translucency (NT) measurements that rely on fixed NT cut-offs for labelling foetuses with high risks for Down syndrome. In the present study, we aimed to plot normative data for NT and the crown-rump length (CRL) in Indian foetuses and to assess the value of using the 95th/99th centiles of NT for CRL cut-offs instead of fixed NT cut-offs to calculate the risk for aneuploidies during the first trimester.

Methods

We conducted a retrospective observational study measuring the NT/CRL in 14,337 Indian foetuses between 11 and 13 + 6 weeks of gestation. We used regression analysis and calculated the 95th/99th centiles of NT distribution. We compared performances of NT > 95th/99th centiles and fixed NT cut-offs of 2.5- and 3.5-mm  as screening.

Results

The NT measurements increased with increasing CRL values. NT > 95th centile for a particular CRL for detecting all aneuploidies had the maximum sensitivity of 73.9% for a false positive rate (FPR) of 4.3%. Similar values for fixed cut-off > 2.5 mm were 63.0% FPR 3.7% (T21 68.2 FPR 3.8%) and for NT > 3.5 mm 36.9% FPR 0.43% (T21 36.5% FPR 0.5%).

Conclusion

A fixed NT cut-off point is not appropriate for the first trimester screening. The best sensitivity for assessing aneuploidies is achieved using the 95th centile, but the 99th centile achieves higher specificity for gestational age.

Noninvasive Approaches to Prenatal Diagnosis: Historical Perspective and Future Directions

The field of prenatal screening and diagnosis has undergone enormous progress over the past four decades. Most of this period has been characterized by gradual improvements in the technical and public health aspects of prenatal screening for Down syndrome. Compared to the direct analysis of fetal cells from amniocentesis or chorionic villus sampling, noninvasive approaches using maternal blood or ultrasound have the great advantage of posing no risk of miscarriage to the pregnancy. Recent advances in molecular genetics and DNA sequencing have revolutionized both the accuracy and the range of noninvasive testing for genetic abnormalities using cell-free DNA in maternal plasma. Many of these advances have already been incorporated into clinical care, including diagnosis of fetal blood group and aneuploidy screening. The accelerated pace of these recent developments is creating not just technical and logistical challenges, but is also magnifying the ethical and public policy issues traditionally associated with this field.

False-positive rates in screening for trisomies 18 and 13: a comparison between first-trimester combined screening and a cfDNA-based approach

PURPOSE

To determine the false-positive rates (FPR) associated with screening for trisomy 18/13 using first-trimester combined screening (FTCS) and an ultrasound plus cfDNA-based approach (US-cfDNA), which includes a detailed ultrasound examination, a cfDNA analysis and a FTCS reflex backup test for cases with uninformative results.

METHODS

This is a sub-analysis of a randomized controlled trial, which was performed between 2015 and 2016. Pregnant women with a normal first-trimester ultrasound examination at 11-13 weeks' gestation (NT < 3.5 mm, no anomalies) were randomized into two groups: FTCS and US-cfDNA screening. The overall FPR in screening for trisomies 18/13 and 21 was compared with the FPR in screening for trisomy 21 alone. Pregnancies were considered screen positive if the risk for trisomy 21 was 1:100 and for trisomy 18 and 13, 1:20 each.

RESULTS

The study population consisted of 688 pregnancies in each study arm. In the FCTS group, median delta NT was 0.0 mm, free beta-hCG and PAPP-A 0.96 and 1.11 MoM. In the US-cfDNA group, median delta NT was 0.0 mm. In 10 pregnancies, the cfDNA analysis was uninformative. In the FTCS and in the US-cfDNA group, the FPR in screening for trisomy 21 was 2.5% and 0%. In both groups, the overall FPR was not increased by adding screening algorithms for trisomies 18 and 13.

CONCLUSION

In conclusion, the addition of screening for trisomies 18 and 13 to screening for trisomy 21 does not significantly change FPR. This is true for both the FTCS and the US-cfDNA-based approach.

Prenatal diagnosis of Down syndrome: A 13-year retrospective study

OBJECTIVE

The aim of this study is to summarize the experience on prenatal diagnosis of Down syndrome.

MATERIALS AND METHODS

The study includes a retrospective data analysis of 157 prenatally detected cases of Down syndrome, routinely diagnosed among 6448 prenatal investigations performed during a 13-year period (2002-2014) in a single tertiary center.

RESULTS

The prevalence of diagnosed Down syndrome cases was 2.4%. Maternal age alone was indication for prenatal diagnosis in 47 cases (45.2%), increased first-/second-trimester biochemical screening test in 34 cases (21.7%), abnormal ultrasound examination in 69 cases (43.9%), positive familial history for chromosomal abnormalities in four cases, and high risk for trisomy 21 revealed by cell-free DNA testing in three cases. Ultrasound anomalies were present in total of 94 fetuses (59.8%). The most common abnormality was cystic hygroma found in 46 cases (29.3%). A regular form of Down syndrome (trisomy 21) was found in 147 cases (93.6%), Robertsonian translocation in six cases (3.8%), and mosaic form in four cases (2.6%).

CONCLUSION

In prenatal diagnosis of Down syndrome noninvasive screening methods are important for estimation of individual risks, in both, young population of woman and older mothers, while conventional and molecular cytogenetic methods are essential for definite diagnosis and proper genetic counseling.

Association between unexplained thickened nuchal translucency and adverse pregnancy outcomes

OBJECTIVE

To determine the association between unexplained increased nuchal translucency (INT) and adverse pregnancy outcomes.

PATIENTS AND METHODS

The prospective database of our fetal down screening project was accessed to retrieve the records with NT measurement and complete follow-up. Pregnancies with pre-existing medical diseases, fetal chromosomal or structural abnormalities were excluded. The selected pregnancies were classified into the INT groups (> 95th percentile), the normal (< 95th percentile) group.

RESULTS

Of 6026 available for analysis (INT:277; and normal: 5749), the abortion rate was significantly higher in the INT group, 18/277 (6.5%) versus 55/5749 (1.0%); p < 0.001. After excluding 73 cases ending-up with abortion, a total of 5953 women were analyzed for final pregnancy outcomes, including 260 (4.4%), and 5693 (95.6%) in the study group (INT), and the control group (normal NT), respectively. The rates of pre-eclampsia (7.3 vs. 4.1%; p: 0.018), preterm birth (12.7 vs. 8.4%; p: 0.023), fetal growth restriction (11.5 vs. 7.6%; p: 0.032), and low birth weight (16.5 vs. 10.0%; p: 0.002) were slightly, but significantly higher in the study group.

CONCLUSIONS

INT in the first trimester is associated with significantly increased risk of abortion, fetal growth restriction, preterm birth, low birth weight and pre-eclampsia.

Isolated Cleft Lip and Palate: Maxillary Gap Sign and Palatino-Maxillary Diameter at 11-13 Weeks

OBJECTIVE

To evaluate the maxillary gap sign and describe markers for the first-trimester diagnosis of isolated cleft lip and palate (CLP) at 11-13 weeks.

METHODS

Firstly, this was a prospective assessment of 1,087 fetuses including 5 cases of isolated CLP in 2 centers which were referred for the 11-13 weeks scan. Secondly, intra- and interobserver variability of the maxillary gap sign was evaluated for observers R.L. and A.B. in 2 sessions (affected cases vs. 50 normal fetuses in each session) to reduce the bias of different ultrasound manufacturer visualizations (Philips, GE). Thirdly, the palatino-maxillary diameter (PMD) was examined in stored images, DICOM loops and volumes of the midsagittal and parasagittal view of the fetal head and brain at 11+0-13+6 weeks of gestation from 5 fetuses with isolated CLP and 302 consecutively assessed normal controls. The PMD values in fetuses with isolated CLP and normal controls were compared.

RESULTS

Firstly, 5 out of 6 referred pregnancies with isolated CLP were detected prospectively using the midsagittal view for measurement of nuchal translucency due to an abnormal appearance. One out of 6 patients with isolated CLP declined the 11-13 weeks scan. Secondly, intra- and interobserver variability showed no false positive cases; all cases with isolated CLP were identified by both sonographers; however, in 2 cases the maxillary gap sign was doubtful. Therefore, thirdly, we developed the PMD measurement which increased significantly with crown-rump length (CRL) from respective mean values at CRL of 45 mm to 4.66 mm and to 8.95 mm at CRL of 84 mm. In the CLP group, the PMD was below the 5th percentile of the control group in 4 out of 5 (80%) cases.

CONCLUSIONS

The midsagittal view for measurement of nuchal translucency shows a high reproducibility regarding abnormal views for maxillary gap sign. In the midsagittal view of the fetal head, face, and brain at 11-13 weeks, the majority of fetuses with isolated CLP have a measurable abnormality in addition, the PMD.

Principles of first trimester screening in the age of non-invasive prenatal diagnosis: screening for chromosomal abnormalities

PURPOSE

First trimester risk assessment for chromosomal abnormalities plays a major role in the contemporary pregnancy care. It has evolved significantly since its introduction in the 1990s, when it essentially consisted of just the nuchal translucency measurement. Today, it involves the measurement of several biophysical and biochemical markers and it is often combined with a cell-free DNA (cfDNA) analysis as a secondary test.

METHODS

A search of the Medline and Embase databases was done looking for articles about first trimester aneuploidy screening. We performed a detailed review of the literature to evaluate the screening tests currently available and their respective test performance.

RESULTS

Combined screening for trisomy 21 based on maternal age, fetal NT, and the serum markers free beta-hCG and PAPP-A results in a detection rate of about 90% for a false positive of 3-5%. With the addition of further ultrasound markers, the false positive rate can be roughly halved. Screening based on cfDNA identifies about 99% of the affected fetuses for a false positive rate of 0.1%. However, there is a test failure rate of about 2%. The ideal combination between combined and cfDNA screening is still under discussion. Currently, a contingent screening policy seems most favorable where combined screening is offered for everyone and cfDNA analysis only for those with a borderline risk result after combined screening.

CONCLUSION

Significant advances in screening for trisomy 21 have been made over the past 2 decades. Contemporary screening policies can detect for more than 95% of affected fetuses for false positive rate of less than 3%.

Observational study comparing the performance of first-trimester screening protocols for detecting trisomy 21 in a North Indian population

OBJECTIVE

To evaluate first-trimester screening protocols for detecting trisomy 21 in an Indian population.

METHODS

The present prospective study collected data from women with singleton pregnancies and a crown-to-rump length of 45-84 mm who presented at the fetal medicine unit of a tertiary care center in North India between June 1, 2006, and December 31, 2015, for combined first-trimester screening. Maternal age, nuchal translucency, nasal bone, and maternal serum levels of free beta human chorionic gonadotropin and pregnancy-associated plasma protein A were assessed for calculating the risk of trisomy 21. Tricuspid regurgitation and qualitative analysis of ductus venosus data were available from June 2010, and were included where available. Trisomy-21 detection rates were calculated for various screening protocols and were compared.

RESULTS

There were 4523 women screened and 24 records of trisomy 21. Combined screening with maternal age, nuchal translucency, nasal bone, tricuspid regurgitation, and ductus venosus demonstrated optimal detection and false-positive rates of 93.8% and 1.9%, respectively. Screening using only maternal age yielded a detection rate of 37.5%; using fixed nuchal translucency cut-off values of 2.5 and 3 mm resulted in detection rates of 66.7% and 37.5%, respectively.

CONCLUSION

Combined first-trimester screening performed well in an Indian population; combining maternal age, nuchal translucency, nasal bone, ductus venosus, and tricuspid regurgitation yielded the most accurate screening.

Automatic detection and measurement of nuchal translucency

In this paper we propose a new methodology to support the physician both to identify automatically the nuchal region and to obtain a correct thickness measurement of the nuchal translucency. The thickness of the nuchal translucency is one of the main markers for screening of chromosomal defects such as trisomy 13, 18 and 21. Its measurement is performed during ultrasound scanning in the first trimester of pregnancy. The proposed methodology is mainly based on wavelet and multi resolution analysis. The performance of our method was analysed on 382 random frames, representing mid-sagittal sections, uniformly extracted from real clinical ultrasound videos of 12 patients. According to the ground-truth provided by an expert physician, we obtained a true positive rate equal to 99.95% with respect to the nuchal region detection and about 64% of measurements present an error equal to 1 pixel (which corresponds to 0.1mm), respectively.

Enlarged NT (≥3.5 mm) in the first trimester - not all chromosome aberrations can be detected by NIPT

BACKGROUND

Since non-invasive prenatal testing (NIPT) in maternal blood became available, we evaluated which chromosome aberrations found in our cohort of fetuses with an enlarged NT in the first trimester of pregnancy (tested with SNP microarray) could be detected by NIPT as well.

METHOD

362 fetuses were referred for cytogenetic testing due to an enlarged NT (≥3.5 mm). Chromosome aberrations were investigated using QF-PCR, karyotyping and whole genome SNP array.

RESULTS

After invasive testing a chromosomal abnormality was detected in 137/362 (38 %) fetuses. 100/362 (28 %) cases concerned trisomy 21, 18 or 13, 25/362 (7 %) an aneuploidy of sex chromosomes and 3/362 (0.8 %) triploidy. In 6/362 (1.6 %) a pathogenic structural unbalanced chromosome aberration was seen and in 3/362 (0.8 %) a susceptibility locus for neurodevelopmental disorders was found. We estimated that in 2-10 % of fetuses with enlarged NT a chromosome aberration would be missed by current NIPT approaches.

CONCLUSION

Based on our cohort of fetuses with enlarged NT we may conclude that NIPT, depending on the approach, will miss chromosome aberrations in a significant percentage of pregnancies. Moreover all abnormal NIPT results require confirmatory studies with invasive testing, which will delay definitive diagnosis in ca. 30 % of patients. These figures are important for pretest counseling enabling pregnant women to make informed choices on the prenatal test. Larger cohorts of fetuses with an enlarged NT should be investigated to assess the additional diagnostic value of high resolution array testing for this indication.

Long-term outcome in apparently healthy children with increased nuchal translucency in the first trimester screening

INTRODUCTION

Increased nuchal translucency is known to be associated with chromosomal and structural defects and genetic syndromes. Little is known about the overall long-term outcome of euploid children after increased nuchal translucency. The aims of this study were to assess the additional structural defects diagnosed after discharge from the delivery hospital and the long-term overall outcome of euploid children after increased nuchal translucency and normal second trimester anomaly scan.

MATERIAL AND METHODS

All children from singleton euploid pregnancies during 2002-2007 with increased nuchal translucency in the first trimester screening, normal second trimester anomaly scan, and discharged as apparently healthy were included. Data on the structural defects and genetic disorders diagnosed until 2012 were retrieved from hospital databases and national registers. Previously published data of structural defects diagnosed after birth but before discharge and of severe neurodevelopmental impairment and genetic syndromes was added.

RESULTS

The cohort included 733 children. During the follow-up time (mean 6.5 years), major structural defects were observed in 10 (1.4%), genetic disorders in two (0.3%), and minor defects in 23 (3.1%) children. In addition, there were 42 previously published major structural defects and major neurodevelopmental impairment or genetic disorders. Adding these results together, major health problems were detected in 54 (7%) euploid children with increased fetal nuchal translucency and normal findings in second trimester anomaly scan.

CONCLUSION

Although only few additional major structural defects are diagnosed during the follow-up after increased fetal nuchal translucency, 7% of fetuses assumed to be healthy after second trimester anomaly scan have a major health impairment.

Noninvasive prenatal testing for fetal trisomy in a mixed risk factors pregnancy population

OBJECTIVE

This study assesses the performance of noninvasive prenatal testing (NIPT) for fetal aneuploidies in a mixed risk factors pregnancy population.

MATERIALS AND METHODS

Data review of 169 pregnant women undergoing prenatal aneuploidy screening in a single tertiary medical center was conducted. Indications included maternal anxiety, advanced maternal age, abnormal nuchal translucency, and high/moderate risk of first trimester Down syndrome screening. Multifetal pregnancies and patients receiving in vitro fertilization were also enrolled for analysis.

RESULTS

A total of 169 patients were enrolled in this study during a time period from July 2012 to June 2014. For patients' ≥ 34 years, anxiety about amniocentesis was the most common reason for patients selecting NIPT for fetal aneuploidy screening, with 107 (88.4%) patients choosing NIPT for this reason. Among the total patient population, two patients showed a positive result from NIPT. One patient displayed 47, XXY, which was confirmed to be a false-positive result. The other patient displayed trisomy 18, which was confirmed by an amniotic cell culture. The sensitivity for NIPT is 100% with the specificity 99.4%.

CONCLUSIONS

NIPT for fetal aneuploidy in a mixed risk factors pregnancy population showed high accuracy. NIPT applied to the low risk population might reassure the anxious family.

[First trimester screening for Down syndrome at Prima facie. A 6-year survey]

OBJECTIVE

To evaluate the results of screening for trisomy 21 by the combined risk of first trimester (as defined by the decree of June 23, 2009) in the Prima facie structure.

METHODS

Single center study involving all patients that were seen for first trimester screening at Prima facie with singleton living pregnancy, not obtained by embryo donation, between 1 January 2009 and 31 December 2014.

RESULTS

Eighteen thousand two hundred and fifty-one patients were included, of which underwent screening for trisomy 21 by the combined risk. One thousand and forty-six (6.1%) had a calculated risk higher than 1/250. Seventy-five were affected by trisomy 21, of whom 65 in the high risk group. The sensitivity and specificity of screening are 86.7% and 94.4%. The median nuchal translucency was 0.98 MoM.

CONCLUSIONS

Screening for trisomy 21 by calculating the combined risk of first trimester enabled to detect 86.7% of trisomy 21 with a false positive rate of 5.6%.

Prenatal diagnosis of fetuses with increased nuchal translucency using an approach based on quantitative fluorescent polymerase chain reaction and genomic microarray

OBJECTIVE

To assess the clinical value of prenatal diagnosis of fetuses with increased nuchal translucency (NT) using an approach based on quantitative fluorescent polymerase chain reaction (QF-PCR) and chromosomal microarray (CMA).

STUDY DESIGN

From January 2013 to October 2014, we included 175 pregnancies with fetal NT ≥ 3.5mm at 11-13 weeks' gestation who received chorionic villus sampling. QF-PCR was first used to rapidly detect common aneuploidies. The cases with a normal QF-PCR result were analyzed by CMA.

RESULTS

Of the 175 cases, common aneuploidies were detected by QF-PCR in 53 (30.2%) cases (30 cases of trisomy 21, 12 cases of monosomy X, 7 cases of trisomy 18, 3 cases of trisomy 13 and 1 case of 47, XXY). Among the 122 cases with a normal QF-PCR result, microarray detected additional pathogenic copy number variants (CNVs) in 5.7% (7/122) of cases. Four cases would have expected to be detectable by conventional karyotyping because of large deletions/duplications (>10 Mb), leaving three cases (2.5%; 3/118) with pathogenic CNVs only detectable by CMA.

CONCLUSION

It is rational to use a diagnostic strategy in which CMA is preceded by the less expensive, rapid, QF-PCR to detect common aneuploidies. CMA allows detection of a number of pathogenic chromosomal aberrations in fetuses with a high NT.

Uncommon Presentation of Triploidy: A Case Report

A 28-year-old woman presented in her first pregnancy was admitted with severe hyperemesis gravidarium. Increased nuchal translucency with cardiac anomaly and omphalocele at the first trimester was observed at the ultrasound examination. Chorionic villus biopsy confirmed triploidy. The combination of type I and type II triploidy patterns were seen together in the second trimester of the pregnancy. Although the symptoms due to increased human chorionic levels occured, at the pathologic investigation there were no molar changes in the placenta. Here we report a case of uncommon presentation of triploidy.