First-trimester contingent screening for trisomies 21, 18 and 13 by fetal nuchal translucency and ductus venosus flow and maternal blood cell-free DNA testing

Is intermediate risk really intermediate? Comparison of karyotype and non-invasive prenatal testing results of pregnancies at intermediate risk of trisomy 21 on maternal serum screening

The purpose of this study was to assess the additional contribution of karyotyping compared with genome-wide non-invasive prenatal testing (NIPT) for pregnancies at intermediate risk for trisomy 21 (T21), calculated using the maternal serum screening without major structural anomalies detected through sonography. Karyotype results of all pregnancies undergoing invasive prenatal diagnostic testing between January 2013 and March 2022 were obtained from a large hospital-based laboratory. Pregnancies with no major structural anomalies on ultrasound (including soft markers) and an intermediate risk for T21 on maternal serum screening were included in this study. The additional contribution of karyotyping for abnormal karyotype results was calculated after excluding results that could theoretically be identified with genome-wide NIPT. Among the 511 pregnancies analyzed, 13 (2.54%) were found to have abnormal karyotype results, 9 (1.76%) of which could theoretically have been detected with genome-wide NIPT. Within the cohort, 6/263 (2.28%) of women aged 35 years and older, and 3/248 (1.20%) of women younger than 35 years had results that could have been detected with genome-wide NIPT. After excluding results detectable using genome-wide NIPT, the additional contribution of karyotyping was found as 4/502 (0.79%) for the entire cohort, 2/257 (0.77%) for women aged 35 years and older, 2/245 (0.81%) for women younger than 35 years. Of the 511 examined pregnancies at intermediate risk for T21 by maternal serum screening, genome-wide NIPT would have failed to detect 4 of 13 abnormal karyotype results. The findings hold importance in guiding couples' informed decision-making processes regarding their choice of genetic screening and diagnostic testing in case of intermediate risk for T21.

The value of combined detailed first-trimester ultrasound-biochemical analysis for screening fetal aneuploidy in the era of non-invasive prenatal testing

PURPOSE

This study aimed to investigate the performance, cost-effectiveness and additional findings of combined detailed ultrasound and biochemical screening for risks of major fetal trisomies in the first-trimester.

METHODS

This is a retrospective analysis study, we estimated the risk of trisomies 21, 18 and 13 based on maternal age, fetal nuchal translucency thickness, nasal bone, ductus venosus pulsatility index velocity, tricuspid regurgitation, fetal heart rate, free beta-human chorionic gonadotropin, and pregnancy-associated plasma protein A in singleton pregnant women, and performed non-invasive prenatal testing for women with risks of trisomy 21 between 1:500 and 1:300. Invasive diagnostic testing was performed for women with positive or failed non-invasive prenatal testing result and in the high-risk group of this screening method. The direct costs were compared between this strategy and the non-invasive prenatal testing which alone used as first-line screening for all pregnant women.

RESULTS

Among 25,155 singleton pregnant women who underwent screening, 24,361 were available for analysis, of these, 194 cases underwent non-invasive prenatal testing. Among the 24,361 women, 39, 19, and 7 had trisomies 21, 18 and 13, respectively. The use of this strategy could potentially detect approximately 94.87% of trisomy 21 cases, 100% of trisomy 18 cases, and 100% of trisomy 13 cases, with false-positive rates of 2.49%, 0.41%, and 0.49%, respectively. The overall detection rate and overall false-positive rates were 96.92% and 2.52%, respectively. The detection rate was 100% in the advanced age group and 94.12% in the general age group. Additionally, structural abnormalities were detected in 137 fetuses, and 44 fetuses had other chromosomal abnormalities. The total cost of this strategy was $3,730,843.30, and the cost per person tested was $153.15. The total cost of using non-invasive prenatal testing as the first-line strategy would be $6,813,387.04 and the cost per person tested was $279.68.

CONCLUSIONS

Our strategy is an efficient and cost-effective approach for detecting major trisomies and identifying more fetuses with a potential abnormality. Therefore, this strategy is a valuable screening method and highly feasible in the clinical setting.

The 'Radiant Effect': Recent Sonographic Image-Enhancing Technique and Its Impact on Nuchal Translucency Measurements

Background: This study assesses the effects of the 'Radiant' image enhancement technique on fetal nuchal translucency (NT) measurements during first-trimester sonographic exams. Methods: A retrospective analysis of 263 ultrasound images of first-trimester midsagittal sections was conducted. NT measurements were obtained using a semi-automatic tool. Statistical methods were applied to compare NT measurements with and without 'Radiant' enhancement. An in vitro setup with predefined line distances provided additional data. Results: Incremental increases in NT measurements were observed with varying levels of 'Radiant' application: an average increase of 0.19 mm with 'Radiant min', 0.24 mm with 'Radiant mid', and 0.30 mm with 'Radiant max.' The in vitro results supported these findings, showing consistent effects on line thickness and measurement accuracy, with the smallest mean deviation occurring at the 'Radiant mid' setting. Conclusions: 'Radiant' image enhancement leads to significant increases in NT measurements. To avoid systematic biases in clinical assessments, it is advisable to disable 'Radiant' during NT measurement procedures. Further studies are necessary to corroborate these findings and to consider updates to the NT reference tables based on this technology.

Maternal Reassurance, Satisfaction, and Anxiety after First-Trimester Screening for Aneuploidies: Comparison between Contingent Screening and Universal Cell-Free DNA Testing

BACKGROUND

This study aims to evaluate maternal reassurance, satisfaction, and anxiety after two different strategies for the first-trimester screening for aneuploidies.

METHODS

Patients between 11 + 3 and 13 + 6 weeks of gestation attending the first-trimester screening at Department of Mother and Child, University Hospital Federico II, Naples, Italy have been recruited and randomly allocated to contingent screening or universal cell-free fetal DNA testing (cffDNA). Questionnaires to measure reassurance, satisfaction, and anxiety have been filled twice: (Q1) after randomization and (Q2) after receiving results. Anxiety was measured by an Italian-version short form of the state scale of the Spielberger State-Trait Anxiety Inventory (STAI); child-related anxiety was measured by the 11-item Pregnancy-Related Anxiety Questionnaire-Revised Regardless of Parity (PRAQ-R2 scale); fear of bearing a physically or mentally handicapped child was measured considering only four items (item 4, 9, 10, and 11) of the PRAQ-R2 scale.

RESULTS

431 patients were recruited: 205 (49%) were randomized in the contingent screening arm, 226 (51%) in the cfDNA arm. Maternal reassurance, satisfaction, and anxiety were not different in the two groups.

CONCLUSION

A contingent screening for aneuploidies in the first trimester seems able to ensure the same maternal reassurance and satisfaction as a cfDNA analysis in the low-risk population and to not affect maternal anxiety.

Effect of Exogenous Progesterone on Fetal Nuchal Translucency: An Observational Study

Introduction Nuchal translucency is a reliable first trimester screening test for fetal structural and chromosomal defects. Neonates with increased nuchal thickness are at greater risk for anomalies. Exogenous progesterone supplementation may affect nuchal translucency and thus the first trimester anomaly screening. We aimed to study if there was a difference in nuchal thickness between women receiving progesterone in the first trimester compared to those who were not supplemented with progesterone. Material and methods Forty-seven women with documented progesterone intake in the first trimester for at least 10 continuous days before the day of the nuchal translucency scan served as the study group compared to 47 other women who did not receive progesterone. Nuchal translucency was measured between 11 and 13 weeks and six days of gestation. Results The mean nuchal translucency increased with increasing gestation in both groups. Maximum mean nuchal translucency was greatest in the age group 18-20 years (1.35 + 0.1 millimeters) in women receiving progesterone compared to 36-40 years (1.65 + 0.49 millimeters) in controls. The mean nuchal translucency in women receiving progesterone was 1.15 + 0.26 millimeters, and in those that did not receive progesterone, it was 1.23 + 0.35 millimeters (p = 0.314). Conclusions Nuchal translucency increased with increasing gestation in both groups, irrespective of progesterone supplementation. There was no significant difference in mean nuchal translucency in women supplemented with progesterone compared to those that did not receive progesterone in the first trimester.

First Trimester Screening - Current Status and Future Prospects After Introduction of Non-invasive Prenatal Testing (NIPT) at a Tertiary Referral Center

Objective To investigate the uptake of different components of first trimester screening (FTS) and the impact on invasive diagnostic testing (IPT) since the introduction of non-invasive prenatal testing (NIPT) at a level III center. Methods Retrospective data analysis was conducted for singleton pregnancies that presented for FTS between 01/2019-12/2019 (group 1, n = 990). Patients were categorized into three risk groups: low risk for trisomy 21 (< 1 : 1000), intermediate risk (1 : 101-1 : 1000) and high risk (≥ 1 : 100). Uptake of NIPT and IPT was analyzed for each of the risk groups. Results were compared to a previous cohort from 2012/2013 (immediately after the introduction of NIPT, group 2, n = 1178). Results Group 1 showed a significant increase in the use of NIPT as part of FTS (29.5% vs. 3.7% for group 2, p = 0.001) in all three risk groups. Overall IPT rates were lower in group 1 (8.6%) vs. group 2 (11.3%, p = 0.038), mainly due to a significant reduction of IPT in the intermediate risk group. IPT rates in the high-risk group remained stable over time. Conclusion Appropriate clinical implementation of NIPT is still currently a challenge for prenatal medicine experts. Our data suggest that widespread uptake of NIPT is becoming more common these days; however, a contingent approach might prevent redundant uptake.

Behavior of the Genetic Markers at Screening during the First Trimester of Pregnancy in Euploid Fetuses

OBJECTIVE

 This study aims to describe the behavior of chromosomopathy screenings in euploid fetuses.

METHODS

 This is a prospective descriptive study with 566 patients at 11 to 14 weeks of gestation. The associations between ultrasound scans and serological variables were studied. For the quantitative variables we used the Spearman test; for the qualitative with quantitative variables the of Mann-Whitney U-test; and for qualitative variables, the X² test was applied. Significance was set at p ≤ 0.05.

RESULTS

 We have found that gestational age has correlation with ductus venosus, nuchal translucency, free fraction of β subunit of human chorionic gonadotropin, pregnancy-associated plasma protein-A and placental growth factor; there is also a correlation between history of miscarriages and nasal bone. Furthermore, we correlated body mass index with nuchal translucency, free fraction of β subunit of human chorionic gonadotropin, and pregnancy-associated plasma protein-A. Maternal age was associated with free fraction of β subunit of human chorionic gonadotropin and pregnancy-associated plasma protein-A.

CONCLUSION

 Our study demonstrates for the first time the behavior of the biochemical and ultrasonographic markers of chromosomopathy screenings during the first trimester in euploid fetuses in Colombia. Our information is consistent with international reference values. Moreover, we have shown the correlation of different variables with maternal characteristics to determine the variables that could help with development of a screening process during the first trimester with high detection rates.

Antenatal screening for chromosomal abnormalities

Screening for chromosomal disorders, especially for trisomy 21, has undergone a number of changes in the last 50 years. Today, cell-free DNA analysis (cfDNA) is the gold standard in screening for trisomy 21. Despite the advantages that cfDNA offers in screening for common trisomies, it must be recognized that it does not address many other chromosomal disorders and any of the structural fetal anomalies. In the first trimester, the optimal approach is to combine an ultrasound assessment of the fetus, which includes an NT measurement, with cfDNA testing. If fetal structural defects are detected or if the NT thickness is increased, an amniocentesis or a CVS with at least chromosomal microarray should be offered.

Universal cell free DNA or contingent screening for trisomy 21 – does it make a difference? A comparative study with real data

Objective: To compare the detection rate for trisomy 21 of universal cell free DNA (cfDNA) screening with contingent screening. Methods: Retrospective study at 3 German centers. The study included euploid and trisomy 21 pregnancies where cfDNA and first trimester (FT) screening assessment was carried out. The FT risk for trisomy 21 was computed based on combined screening and stratified into the following classes: high risk >1:10, intermediate risk 1:11 – 2,500, low risk <1:2,500. For universal cfDNA screening, the cfDNA test results were examined. For the contingent screening model, the result of the cfDNA test was taken into account in case of an intermediate FT risk. Different strategies combining maternal age, nuchal translucency, nasal bone, beta-hCG and PAPP-A were evaluated. Screen-positivity was defined as either a high risk after first trimester screening or a cfDNA test indicating a high risk result. An inconclusive cfDNA test was also considered as screen positive. Results: The search of the database identified 2,255 euploid and 163 affected pregnancies. All affected fetuses were identified by universal cfDNA screening. 1.3% of the euploid fetuses were classified as screen positive due to final inconclusive cfDNA test result. The detection and false positive rate of a contingent approach that is based on combined screening and cfDNA screening in the intermediate group would be 98.4% and 0.7%, respectively. With this approach, cfDNA screening would be necessary in only about 27% of all pregnancies. Conclusion: This study demonstrates that a contingent approach provides similar detection rates for trisomy 21 as universal cfDNA screening, by reducing in 73% the number of cfDNA tests.

Karyotype analysis of amniotic fluid cells and report of chromosomal abnormalities in 15,401 cases of Iranian women

The aim of present study was to assess the karyotypes of amniotic fluid cells and find the frequency of chromosomal abnormalities and their significance in clinical setting. A total of 15,401 pregnant women were assessed from March 2016 to May 2019, and 14,968 amniotic fluid samples were successfully cultured. These fetuses were grouped according to different indications including advanced maternal age, abnormal nuchal translucency (NT) values, positive first/second trimester screening results, high risk NIPT results, very low PAPP-A and free β-hCG multiples of the normal median (MoM) results, abnormal ultrasound findings or previous history of chromosomal abnormalities. Results indicated the presence of normal karyotype in 90.2% (13,497/14,968) of fetuses. Totally, 46.4% (6945/14,968) of fetuses were 46,XX and 43.8% (6552/14,968) had 46,XY chromosome pattern. A total of 1077 abnormal karyotypes were found among 14,968 fetuses, thus the rate of abnormal fetuses was calculated to be 7.2% (1072/14,968). Meanwhile, a total of 394 cases (2.8%) had a normal polymorphism in their karyotype. In other words, abnormal karyotypes were detected in one of 13.9 cases of patients underwent amniocentesis. Down syndrome, Edward’s syndrome, abnormal mosaicisms and Patau’s syndrome were detected in 4.4% (659/14,968), 0.57% (85/14,968), 0.49% (74/14,968) and 0.24% (36/14,968) of cases, respectively. Sex chromosomal abnormalities including Klinefelter syndrome, Turner syndrome and 47,XXX karyotype were detected in 64 cases (0.43%). In this article, the rates of chromosomal abnormalities are compared between different groups of patients based on the advanced maternal age, abnormal NT values, very low PAPP-A and free β-hCG MoMs results, and positive FTS results. The current investigation provides insight into the most appropriate indications for amniocentesis in Iran.

Does abnormal ductus venosus pulsatility index at the first-trimester effect on adverse pregnancy outcomes?

AIM

The ductus venosus pulsatility index for veins (DV PIV) has become a popular marker of the first-trimester scan. The aim of this study is to search for any difference between groups with normal and abnormal DV PIV values in terms of adverse pregnancy outcomes.

METHODS

We retrospectively evaluated 556 women whose first-trimester scan was performed. The ductus venosus pulsatility indices were examined at singleton pregnancies between 11 and 14 weeks of gestation. Patients were categorized as Group-I with normal DV PIV (DV PIV ≥ 0.73, ≤1.22) and as Group-II with abnormal DV PIV. Group-II was subgrouped as Group-IIA which composed of patients with DV PIV < 0.73 and as Group-IIB with DV PIV > 1.22.

RESULTS

There were 451 subjects in Group-I and 105 subjects in Group-II (Group-IIA = 32 and Group-IIB = 73). The comparisons between major groups revealed a statistically significant increase about miscarriage (p = 0.002), stillbirth (p < 0.001), small for gestational age (p = 0.033), low birth weight (p < 0.001), fetal growth restriction (p = 0.048), and major congenital heart defect (p=<0.001) in Group-II. This difference is mainly due to Group-IIB. There is no difference in preterm delivery, preeclampsia and gestational diabetes between Group I and II.

CONCLUSION

Routinely monitoring DIV PIV as a first-trimester screening should provide valuable information regarding adverse pregnancy outcomes such as miscarriage, stillbirth, small for gestational age, low birth weight, fetal growth restriction and major congenital heart defect.

First-trimester screening-biomarkers and cell-free DNA

Background: The introduction of cell-free DNA into clinical practice has changed the screening approach. Healthcare professionals and future parents tend to overestimate NIPT (noninvasive prenatal testing) capabilities despite its relatively high cost and limited information.Objective: In this review, our aim was to survey how various countries have introduced contingent screening models and to discuss the advantages and disadvantages of the combined screening test and the use of NIPT.Data source: The Web of Science, PubMed database and institutional websites were searched for information regarding screening approaches and the implementation in different countries.Results: There are nine countries and regions that have already approved contingent screening test, while others (e.g. Australia) are discussing the implementation of contingent screening versus universal use of NIPT. There are several recent meta-analyses debating whether to use NIPT for universal screening for trisomies and other fetal conditions.Conclusions: NIPT is a reasonable option as an advanced screening test for trisomy 21, 18 and 13 only. Introducing screening by NIPT instead of a first-trimester screening will cause the loss of other valuable information including accurate dating of pregnancy, diagnosing major structural fetal abnormalities and multiple pregnancies at an early gestational age. Additionally, the opportunity to screen for early preeclampsia will be lost. Currently, the price for NIPT is still high adding extra strain on publicly funded health systems.

Implementation of maternal blood cell-free DNA testing in early screening for aneuploidies

Several externally blinded validation and implementation studies in the last 9 years have shown that it is now possible, through analysis of cell-free (cf) DNA in maternal blood, to effectively detect a high proportion of fetuses affected by trisomies 21, 18, and 13 at a much lower false-positive rate (FPR) than all other existing screening methods. This article is aimed at reviewing technical and clinical considerations for implementing cfDNA testing in routine practice, including methods of analysis, performance of the test, models for clinical implementation, and interpretation of results.

Nicht invasive Pränataldiagnostik mittels molekulargenetischer Tests (NIPT) zur Erkennung der Trisomien 13, 18 und 21

Hintergrund

Molekulargenetische Tests (NIPT) auf Trisomie sind längst Teil der nicht invasiven Pränataldiagnostik (NIPD). In Deutschland wird derzeit geprüft, ob und für wen diese Tests von den gesetzlichen Krankenkassen künftig bezahlt werden sollen.

Fragestellung

(I) Diagnostische Eigenschaften der NIPT zur Entdeckung der Trisomien 13, 18 und 21 und (II) hypothetische Berechnung der möglichen Anwendung der NIPT in verschiedenen Gruppen.

Methoden

(I) Systematische Recherche nach Primärliteratur und systematischen Übersichten in MEDLINE und vier weiteren Datenbanken. Einschlusskriterien: Studien mit schwangeren Frauen, Indextest: NIPT mittels molekulargenetischer Analyse von cffDNA im mütterlichen Blut zur Bestimmung des Trisomie-Risikos; Referenztest: zytogenetische Diagnostik oder postnatale klinische Untersuchung. (II) Orientierende Recherche. Hypothetische Berechnungen für (1) alle schwangeren Frauen nach aktuellem Vorgehen ohne NIPT am Beispiel von Ersttrimesterscreening (ETS), (2) Anwendung bei schwangeren Frauen mit erhöhtem Risiko, z. B. nach vorgeschaltetem auffälligem ETS und (3) NIPT in einer Population mit und ohne erhöhtes Risiko für eine Trisomie.

Ergebnisse

Bei 22 eingeschlossenen Studien lagen die Sensitivität und die Spezifität zur Erkennung der Trisomie 21 bei 99,13 % (95 %-KI: [97,39 %; 99,72 %]) und 99,95 % (95 %-KI: [99,88 %; 99,98 %]). Der mögliche Einfluss von Testversagern blieb bei den Berechnungen unberücksichtigt, womit die Sensitivität oder die Spezifität der NIPT möglicherweise überschätzt wurde. Für die Erkennung der Trisomien 13 und 18 konnte jeweils die Sensitivität nicht robust geschätzt werden.

Diskussion

Bei Frauen mit erhöhtem Risiko können NIPT die Zahl der invasiven Tests und damit der testbedingten Fehlgeburten vermutlich verringern.

Prenatal chromosomal microarray testing of fetuses with ultrasound structural anomalies: A prospective cohort study of over 1000 consecutive cases

OBJECTIVE

Evaluate the diagnostic yield of prenatal submicroscopic chromosome anomalies using prenatal array comparative genomic hybridisation (aCGH).

METHOD

Prospective cohort study conducted between March 2013 and June 2017 including fetuses where an elevated nuchal translucency (NT) or structural anomaly was identified on ultrasound and common aneuploidy testing was negative. aCGH was performed using an 8-plex oligonucleotide platform with a genome wide backbone resolution of greater than 200 kb and interpretation in line with American College of Medical Genetics guidance.

RESULTS

One thousand one hundred twenty-nine fetuses were included; 371 fetuses with an increased NT (32.9%) and 758 with a structural anomaly (67.1%). The rate of pathogenic copy number variants (CNVs) and variant of uncertain significance (VUS) was 5.9% (n = 22) and 0.5% (n = 2) in the elevated NT group and 7.3% (n = 55) and 0.8% (n = 6) in the mid-trimester anomaly group. No pathogenic CNVs were identified in fetuses with an NT less than 4.0 mm. Multisystem and cardiac anomalies had the greatest yield of pathogenic CNV with a 22q11.2 microdeletion present in 40% (12/30).

CONCLUSION

Prenatal aCGH is a useful diagnostic tool in the investigation of fetuses with a significantly elevated NT or structural anomaly. With time and experience, rates of pathogenic CNVs have increased, and VUS have reduced, supporting the prenatal application of increasingly high resolution aCGH platforms.

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.

Clinical Significance of Ductus Venosus Waveform as Generated by Pressure- volume Changes in the Fetal Heart

The ductus venosus is a vascular shunt situated within the fetal liver parenchyma, connecting the umbilical vein to the inferior vena cava. This vessel acts as a bypass of the liver microcirculation and plays a critical role in the fetal circulation. The ductus venosus allows oxygenated and nutrient-rich venous blood to flow from the placenta to the myocardium and brain. Increased impedance to flow in the fetal ductus venosus is associated with fetal aneuploidies, cardiac defects and other adverse pregnancy outcomes. This review serves to improve our understanding of the mechanisms that regulate the blood flow redistribution between the fetal liver circulation and fetal heart and the clinical significance of the ductus venosus waveform as generated by pressure-volume changes in the fetal heart.

Intelligent Noninvasive Diagnosis of Aneuploidy: Raw Values and Highly Imbalanced Dataset

The objective of this paper is to introduce a noninvasive diagnosis procedure for aneuploidy and to minimize the social and financial cost of prenatal diagnosis tests that are performed for fetal aneuploidies in an early stage of pregnancy. We propose a method by using artificial neural networks trained with data from singleton pregnancy cases, while undergoing first trimester screening. Three different datasets¹ with a total of 122 362 euploid and 967 aneuploid cases were used in this study. The data for each case contained markers collected from the mother and the fetus. This study, unlike previous studies published by the authors for a similar problem differs in three basic principles: 1) the training of the artificial neural networks is done by using the markers' values in their raw form (unprocessed), 2) a balanced training dataset is created and used by selecting only a representative number of euploids for the training phase, and 3) emphasis is given to the financials and suggest hierarchy and necessity of the available tests. The proposed artificial neural networks models were optimized in the sense of reaching a minimum false positive rate and at the same time securing a 100% detection rate for Trisomy 21. These systems correctly identify other aneuploidies (Trisomies 13&18, Turner, and Triploid syndromes) at a detection rate greater than 80%. In conclusion, we demonstrate that artificial neural network systems can contribute in providing noninvasive, effective early screening for fetal aneuploidies with results that compare favorably to other existing methods.

Diagnostic performance and costs of contingent screening models for trisomy 21 incorporating non-invasive prenatal testing

BACKGROUND

Contingent screening for trisomy 21 using non-invasive prenatal testing has the potential to reduce invasive diagnostic testing and increase the detection of trisomy 21.

AIM

To describe the diagnostic and economic performance of prenatal screening models for trisomy 21 that use non-invasive prenatal testing as a contingent screen across a range of combined first trimester screening risk cut-offs from a public health system perspective.

METHODS

Using a hypothetical cohort of 300 000 pregnancies, we modelled the outcomes of 25 contingent non-invasive prenatal testing screening models and compared these to conventional screening, offering women with a high-risk (1 > 300) combined first trimester screening result an invasive test. The 25 models used a range of risk cut-offs. High-risk women were offered invasive testing. Intermediate-risk women were offered non-invasive prenatal testing. We report the cost of each model, detection rate, costs per diagnosis, invasive tests per diagnosis and the number of fetal losses per diagnosis.

RESULTS

The cost per prenatal diagnosis of trisomy 21 using the conventional model was $51 876 compared to the contingent models which varied from $49 309-66 686. The number of diagnoses and cost per diagnosis increased as the intermediate-risk threshold was lowered. Results were sensitive to trisomy 21 incidence, uptake of testing and cost of non-invasive prenatal testing.

CONCLUSION

Contingent non-invasive prenatal testing models using more sensitive combined first trimester screening risk cut-offs than conventional screening improved the detection rate of trisomy 21, reduced procedure-related fetal loss and could potentially be provided at a lower cost per diagnosis than conventional screening.

First trimester contingent screening for trisomies 21,18,13: is this model cost efficient and feasible in public health system?

PURPOSE

To evaluate the effectiveness of three different first trimester screening models for trisomies 21, 18 and 13, in terms of detection rate, invasive test rate and final costs.

MATERIAL AND METHODS

We analyzed the distribution of risk for trisomies 21, 18 and 13 in a population of 20,831 singleton pregnancies based on maternal age, fetal heart rate, nuchal translucency, free beta human chorionic gonadotropin and pregnancy-associated plasma protein A (Combined test). On the basis of our data, we estimated the performance and cost of screening for trisomies using three different models at specific cutoffs: Combined test; Cell free DNA test and Contingent screening test.

RESULTS

Using Combined test, DR for major trisomies was estimated to be 94.92%, invasive test rate was 6.3%. cfDNA would result in a DR of 97.92%, with an invasive test rate of 3.64%. Contingent screening approach would result in an overall DR of 97.82, with a rate for invasive procedure of 1.36% and a final cost lower than other screening policies (2,338,433 euro vs 5,796,060 of cfDNA and 2,385,473 of Combined test).

CONCLUSIONS

Contingent screening test could be a cost-efficient and feasible first trimester screening test for aneuploidies in public health system.

Should cell-free fetal DNA be included in first trimester screening (FTS) for common trisomy? A possible scenario on 6697 women screened over 10 years

OBJECTIVE

The primary aim was to determine the performance of the first trimester screening (FTS) test in a general obstetrics population. Cost-benefit analysis of a hypothetic model based on implementation of the FTS test by cell-free fetal (cff) DNA was calculated.

METHODS

A total of 6697 women were screened using FTS test. A two-step strategy based upon nuchal translucency, serum screening and ultrasound assessment of nasal bone (NB) was applied. Three groups were identified (high-risk: >1:250; intermediate-risk: 1:251-1:999 and low-risk group: <1:1000). Women at intermediate-risk (1:251-1:999) underwent NB assessment and recalculation of individual risk. All women at high-risk were offered fetal karyotyping.

RESULTS

A total of 321 women (4.8%) resulted at high-risk while 480 women (7.1%) with intermediate-risk underwent assessment of the NB, which was absent in 15 fetuses. Overall, 54 aneuploidies were detected for a 96.4% sensitivity, a 96.1% specificity, a 99.9% negative predictive value and a false positive rate of 4.8%. Audit was conducted on a yearly basis and lost to follow up was 0.47% (32 cases).

CONCLUSIONS

Public health system would not be able to cover the cost of including cff DNA in women undergoing first trimester screening on universal basis. However, assuming a possible scenario based on implementation of FTS by cff DNA in women at high-risk would result in a 6-fold reduction in the number of invasive procedures while avoiding two false negative results (trisomy 21) that were diagnosed in women with intermediate-risk using current screening strategy by combined test.

National survey of Australian sonographer knowledge and behaviour surrounding the ALARA principles when conducting the 11-14-week obstetric screening ultrasound

OBJECTIVES

To identify gaps in Australian sonographer's knowledge and application of as low as reasonably achievable (ALARA) principles during first trimester imaging; Identify relationships between demographic variables and knowledge or application of the Output Display Standard (ODS) value thermal index (TI) and compare Australian sonographers to their international peers.

METHODS

Australian Sonographer Accreditation Registered ( ASAR)-registered sonographers completed a voluntary questionnaire over September 2015 after institutional ethics approval (RDSE-48-15). Seventeen questions detailed their demographics (5); knowledge of ultrasound bioeffects terminology and ALARA principles (9); behaviour surrounding ALARA and first trimester imaging (2) and continuing bioeffects education (1). Exclusion criteria was non-ASAR status. Descriptive (mode frequency) and inferential statistics (Fisher exact test) were used. Significance level was 95%.

RESULTS

Ninety-five valid surveys were collected. Ninety-nine per cent knew the meaning of ALARA, 93.55% correctly defined 'TI' and 85.39% knew where to find the TI value via the ODS. Half never monitor the ODS. No correlation (P = 0.094) was found between experience and ODS monitoring. No statistical difference (P = 0.189) existed between obstetric and non-obstetric sonographers who knew the meaning of TIB (87.18% vs. 76.92%) or those who correctly identified it as the setting for 11-14-week examinations (30.77% vs. 30.77%). When using Doppler during obstetric examinations, no difference existed (P = 0.293), between obstetric and non-obstetric sonographers' knowledge of ASUM/WFUMB guidelines for maximum TI (47.37% vs. 46.15%).

CONCLUSIONS

Despite poor ODS usage, Australian sonographers outperform their international peers for ALARA literacy, and show better application of ALARA principles in the first trimester. No relationships were found between demographic variables and knowledge or conscious monitoring of ODS.

Contingent non-invasive prenatal testing: an opportunity to improve non-genetic aspects of fetal aneuploidy screening

BACKGROUND

Several countries today struggle with suboptimal performances in many aspects of the fetal aneuploidy screening process and consider introducing non-invasive prenatal screening (NIPT) as a solution. In this study, costs and benefits of different scenarios for contingent NIPT screening in Belgium are evaluated with respect to partial redistribution of the national screening budget into quality improving measures for those screening activities that will be maintained when full NIPT screening is implemented.

METHODS

Data from the Belgian National Institute for Health and Disability Insurance and the Study Centre for Perinatal Epidemiology were used in modeled calculations of medical and economic impact of NIPT after prior conventional screening (1) at thresholds 1:300 and 1:600, and (2) at current and improved screening sensitivity.

RESULTS

Contingent NIPT screening under current screening conditions would maintain today's 7.9(0)/000 live birth prevalence of Down syndrome (LBPD) at an 11% reduction of overall short-term costs. Lowering the screening threshold to 1:600 or increasing sensitivity by 10% would reduce LBPD to 7(0)/000 at a maximum 3% increase of overall short-term costs.

CONCLUSION

Today, in Belgium and in many other countries, full NIPT screening is considered too expensive for immediate introduction into the national fetal aneuploidy screening program. Contingent NIPT screening is both clinically and economically beneficial. A temporary contingent NIPT protocol allows for reinvesting economic savings into optimization of those screening aspects, which are to be maintained in parallel to full NIPT screening.

Evaluating first trimester maternal serum screening combinations for Down syndrome suitable for use with reflexive secondary screening via sequencing of cell free DNA: high detection with low rates of invasive procedures

OBJECTIVES

Examine primary Down syndrome screening using combinations of first trimester serum markers, with and without sequencing of cell free DNA as a secondary reflexive test.

METHODS

Samples from 40 Down syndrome cases were matched with five control samples and tested for PAPP-A, free β, AFP, inhibin-A and PlGF. Results were converted to weight-adjusted multiples of the median (MoM) and population parameters computed. Monte Carlo simulation modeled Down syndrome detection and false positive rates for various marker combinations. After reflexive DNA testing, the revised detection and false positive rates were also computed.

RESULTS

At a primary false positive rate of 20%, the baseline combination (maternal age, PAPP-A and free β) detected 86.9%. Adding AFP or PlGF increased detection to 89.8% and 89.5%, respectively. Adding AFP and PlGF, AFP and inhibin-A, or all three markers, detected 93.7%, 94.1% and 95.5%, respectively. Modeling reflexive cf DNA testing results in little loss in detection (1%), but false positive rates fall to 0.2%.

CONCLUSION

First trimester reflexive testing does not require nuchal translucency measurements, and has high detection and very low rates of invasive procedures. However, timing of DNA sample collection and the costs of sample collection and DNA testing need to be considered before implementation.

Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: updated meta-analysis

OBJECTIVE

To review clinical validation or implementation studies of maternal blood cell-free (cf) DNA analysis and define the performance of screening for fetal trisomies 21, 18 and 13 and sex chromosome aneuploidies.

METHODS

Searches of PubMed, EMBASE and The Cochrane Library were performed to identify all peer-reviewed articles on cfDNA testing in screening for aneuploidies between January 2011, when the first such study was published, and 4 January 2015.

RESULTS

In total, 37 relevant studies were identified and these were used for the meta-analysis on the performance of cfDNA testing in screening for aneuploidies. These studies reported cfDNA results in relation to fetal karyotype from invasive testing or clinical outcome. Weighted pooled detection rates (DR) and false-positive rates (FPR) in singleton pregnancies were 99.2% (95% CI, 98.5-99.6%) and 0.09% (95% CI, 0.05-0.14%), respectively, for trisomy 21, 96.3% (95% CI, 94.3-97.9%) and 0.13% (95% CI, 0.07-0.20) for trisomy 18, 91.0% (95% CI, 85.0-95.6%) and 0.13% (95% CI, 0.05-0.26%) for trisomy 13, 90.3% (95% CI, 85.7-94.2%) and 0.23% (95% CI, 0.14-0.34%) for monosomy X and 93.0% (95% CI, 85.8-97.8%) and 0.14% (95% CI, 0.06-0.24%) for sex chromosome aneuploidies other than monosomy X. For twin pregnancies, the DR for trisomy 21 was 93.7% (95% CI, 83.6-99.2%) and the FPR was 0.23% (95% CI, 0.00-0.92%).

CONCLUSION

Screening for trisomy 21 by analysis of cfDNA in maternal blood is superior to that of all other traditional methods of screening, with higher DR and lower FPR. The performance of screening for trisomies 18 and 13 and sex chromosome aneuploidies is considerably worse than that for trisomy 21.