What will be the role of first-trimester ultrasound if cell-free DNA screening for aneuploidy becomes routine?

Disparities in integrating non-invasive prenatal testing into antenatal healthcare in Australia: a survey of healthcare professionals

BACKGROUND

Non-invasive prenatal testing (NIPT) has been clinically available in Australia on a user-pays basis since 2012. There are numerous providers, with available tests ranging from targeted NIPT (only trisomies 21, 18, and 13 +/- sex chromosome aneuploidy) to genome-wide NIPT. While NIPT is being implemented in the public health care systems of other countries, in Australia, the implementation of NIPT has proceeded without public funding. The aim of this study was to investigate how NIPT has been integrated into antenatal care across Australia and reveal the successes and challenges in its implementation in this context.

METHODS

An anonymous online survey was conducted from September to October 2022. Invitations to participate were sent to healthcare professionals (HCPs) involved in the provision of NIPT in Australia through professional society mailing lists and networks. Participants were asked questions on their knowledge of NIPT, delivery of NIPT, and post-test management of results.

RESULTS

A total of 475 HCPs responded, comprising 232 (48.8%) obstetricians, 167 (35.2%) general practitioners, 32 (6.7%) midwives, and 44 (9.3%) genetic specialists. NIPT was most commonly offered as a first-tier test, with most HCPs (n = 279; 60.3%) offering it to patients as a choice between NIPT and combined first-trimester screening. Fifty-three percent (n = 245) of respondents always offered patients a choice between NIPT for the common autosomal trisomies and expanded (including genome-wide) NIPT. This choice was understood as supporting patient autonomy and informed consent. Cost was seen as a major barrier to access to NIPT, for both targeted and expanded tests. Equitable access, increasing time demands on HCPs, and staying up to date with advances were frequently reported as major challenges in delivering NIPT.

CONCLUSIONS

Our findings demonstrate substantial variation in the clinical implementation of NIPT in Australia, including in the offers of expanded screening options. After a decade of clinical use, Australian clinicians still report ongoing challenges in the clinical and equitable provision of NIPT.

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.

Inverted pyramid of prenatal care - is it enough? Should it be - extended inverted pyramid of prenatal care?

In recent years, the idea of the inverted pyramid of prenatal care and monitoring has emerged, for the purpose of prediction and prevention, early detection and treatment of health disorders of the fetus. Is this enough? If we analyze the period behind us, progress has been made in the field of detection of multiple pregnancies, dating of pregnancy and prenatal detection of chromosomal and structural fetal disorders, as well as a small amount of progress in terms of prediction and prevention of preeclampsia. If these disorders are the consequence of the disturbed or dysfunctional placentation, they are rooted at the time of implantation. This means that the changes that lead to the dysfunctional implantation should be sought in the pre-implantation period, in relation between the embryo and the endometrium. An extended inverted pyramid is necessary to find better results in perinatal medicine. This means that the interventions should be focused on the preconception and peri-implantation periods. The therapy should be on the subcellular and genetic level by applying the latest biotechnological procedures. It is possible that the time is approaching when the listed disorders of a pregnancy will be the indications for the application of a non stimulated in-vitro fertilization (IVF) (without ovary stimulating medication) with the use of new biotechnological achievements.

Diagnosis of Fetal Structural Anomalies at 11 to 14 Weeks

OBJECTIVES

To assess the performance of first-trimester ultrasound (US) in identifying major fetal structural abnormalities in an unselected population.

METHODS

We conducted a retrospective analysis of all pregnancies that underwent the 11- to 14-week scan in the Fetal Medicine Department of Filantropia Hospital in Bucharest, which were prospectively examined within our screening program. The purpose of the first-trimester US was to evaluate the risk for chromosomal abnormalities and to conduct fetal anatomic examination using a detailed protocol.

RESULTS

Our population consisted of 7480 pregnant patients (7576 fetuses). The follow-up was completed for 6045 patients (6114 fetuses). The prevalence of major structural anomalies was 1.89%. In the first trimester, we identified 79% of all major structural anomalies. The highest detection rates were achieved for abdominal wall defects (100%), major central nervous system anomalies (88%), cardiac defects (74%), and skeletal anomalies (71%). The nuchal translucency was increased in 35% of the cases with structural anomalies, and 95% of these were diagnosed in the first trimester. Seventy percent of the patients who presented with structural anomalies and a normal nuchal translucency were diagnosed in the first trimester.

CONCLUSIONS

Our results emphasize the importance of performing a detailed US examination at 11 to 14 weeks' gestation in identification of fetal structural defects.

Prenatal diagnostic testing and atypical chromosome abnormalities following combined first-trimester screening: implications for contingent models of non-invasive prenatal testing

OBJECTIVES

To investigate by means of a population-based analysis of a cohort of women who underwent combined first-trimester screening (CFTS), changes in uptake of invasive prenatal diagnosis according to risk of trisomy 21 (T21) on CFTS, and prevalence and methods for ascertainment of atypical chromosome abnormalities.

METHODS

This was a retrospective cohort study using state-wide prenatal datasets from Victoria, Australia. A three-step approach was taken to analyze the data: (1) linkage of records between serum screening and diagnostic results; (2) comparison of rates of diagnostic testing according to CFTS T21 risk result category in a 2014-2015 cohort with those of a historical 2002-2004 cohort; (3) detailed analysis of atypical abnormalities in the 2014-2015 group according to CFTS T21 risk result, individual serum analyte level and other indications for invasive diagnostic testing.

RESULTS

In 2014-2015, there were 100 418 CFTS results issued for 146 776 births (68.4%). The overall prevalence of atypical chromosome abnormalities in the entire CFTS cohort was 0.10% and was highest in those with CFTS T21 risk > 1 in 10 (4.6%), or serum analyte levels < 0.2 multiples of the median (MoM) (6.9% for pregnancy-associated plasma protein-A (PAPP-A) and 5.2% for beta-human chorionic gonadotropin (β-hCG)). Almost half (49.2%) of women with PAPP-A < 0.2 MoM had a risk for T21 on CFTS of less than 1 in 100. The majority (55%) of atypical abnormalities occurred in women with CFTS T21 risk below 1 in 300, and were most commonly detected on ultrasound examination (47.1%).

CONCLUSION

Concerns regarding missed diagnoses of atypical chromosome abnormalities when non-invasive prenatal testing is offered after a result of high risk on CFTS can be mitigated if invasive diagnostic testing is offered to those women with CFTS T21 risk of > 1 in 100, serum PAPP-A or β-hCG < 0.2 MoM, or ultrasound-detected abnormality. This has implications for contingent models of screening. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

First-trimester screening for early and late preeclampsia using maternal characteristics, biomarkers, and estimated placental volume

BACKGROUND

Preeclampsia is a major cause of perinatal morbidity and mortality. First-trimester screening has been shown to be effective in selecting patients at an increased risk for preeclampsia in some studies.

OBJECTIVE

We sought to evaluate the feasibility of screening for preeclampsia in the first trimester based on maternal characteristics, medical history, biomarkers, and placental volume.

STUDY DESIGN

This is a prospective observational nonintervention cohort study in an unselected US population. Patients who presented for an ultrasound examination between 11-13+6 weeks' gestation were included. The following parameters were assessed and were used to calculate the risk of preeclampsia: maternal characteristics (demographic, anthropometric, and medical history), maternal biomarkers (mean arterial pressure, uterine artery pulsatility index, placental growth factor, pregnancy-associated plasma protein A, and maternal serum alpha-fetoprotein), and estimated placental volume. After delivery, medical records were searched for the diagnosis of preeclampsia. Detection rates for early-onset preeclampsia (<34 weeks' gestation) and later-onset preeclampsia (≥34 weeks' gestation) for 5% and 10% false-positive rates using various combinations of markers were calculated.

RESULTS

We screened 1288 patients of whom 1068 (82.99%) were available for analysis. In all, 46 (4.3%) developed preeclampsia, with 13 (1.22%) having early-onset preeclampsia and 33 (3.09%) having late-onset preeclampsia. Using maternal characteristics, serum biomarkers, and uterine artery pulsatility index, the detection rate of early-onset preeclampsia for either 5% or 10% false-positive rate was 85%. With the same protocol, the detection rates for preeclampsia with delivery <37 weeks were 52% and 60% for 5% and 10% false-positive rates, respectively. Based on maternal characteristics, the detection rates for late-onset preeclampsia were 15% and 48% for 5% and 10%, while for preeclampsia at ≥37 weeks' gestation the detection rates were 24% and 43%, respectively. The detection rates for late-onset preeclampsia and preeclampsia with delivery at >37 weeks' gestation were not improved by the addition of biomarkers.

CONCLUSION

Screening for preeclampsia at 11-13+6 weeks' gestation using maternal characteristics and biomarkers is associated with a high detection rate for a low false-positive rate. Screening for late-onset preeclampsia yields a much poorer performance. In this study the utility of estimated placental volume and mean arterial pressure was limited but larger studies are needed to ultimately determine the effectiveness of these markers.

Population-based impact of noninvasive prenatal screening on screening and diagnostic testing for fetal aneuploidy

PurposeTo assess the population-wide impact of noninvasive prenatal screening (NIPS) on combined first-trimester screening (CFTS), early ultrasound (11-13 weeks), and invasive prenatal diagnosis in a state with over 73,000 births per year.MethodsAnalysis of population-based data from 2000 to 2015 including (i) invasive prenatal tests, (ii) CFTS uptake, and (iii) total births. Utilization of early ultrasound was analyzed before and after NIPS (2010-2015).ResultsInvasive testing decreased significantly by 39.6% from 2012 to 2015 despite steady births. More than half of all confirmed cases of trisomy 21 were ascertained by NIPS in 2015, despite NIPS comprising only 11.7% of total indications for invasive testing. CFTS uptake declined significantly from 77.5% in 2013 to 68.1% in 2015, but 11- to 13-week ultrasounds did not. In 2015, ultrasound abnormality replaced CFTS as the most common indication for invasive testing and chromosomal microarray was performed for 85.3% of all prenatal karyotypes.ConclusionPrenatal testing is now unequivocally in the genomic era. NIPS is now the screening test that precedes the majority of confirmed diagnoses of trisomy 21. The contributions of NIPS, early ultrasound, and chromosome microarray have led to unprecedented detection rates of major chromosome abnormalities, now found in 20% of all invasive tests.

Inverted Pyramid of Care

First-trimester pregnancy evaluation using fetal and maternal parameters not only allows for diagnoses to be made early in gestation but can also assess the risk of complications that become clinically evident later in pregnancy. This evaluation makes it possible for pregnancy care to be individualized. In select cases, treatment that reduces the risk of complications can be started early in pregnancy. Even though cell free DNA is a significant advance in diagnosing fetal aneuploidy, the combination of first-trimester ultrasound and maternal serum biochemistries casts a much wider diagnostic net; therefore, the 2 technologies are best used in combination.

Cell-free fetal DNA screening in the USA: a cost analysis of screening strategies

OBJECTIVES

To determine whether implementation of primary cell-free fetal DNA (cffDNA) screening would be cost-effective in the USA and to evaluate potential lower-cost alternatives.

METHODS

Three strategies to screen for trisomy 21 were evaluated using decision tree analysis: 1) a primary strategy in which cffDNA screening was offered to all patients, 2) a contingent strategy in which cffDNA screening was offered only to patients who were high risk on traditional first-trimester screening and 3) a hybrid strategy in which cffDNA screening was offered to all patients ≥ 35 years of age and only to patients < 35 years who were high risk after first-trimester screening. Four traditional screening protocols were evaluated, each assessing nuchal translucency (NT) and pregnancy-associated plasma protein-A (PAPP-A) along with either free or total beta-human chorionic gonadotropin (β-hCG), with or without nasal bone (NB) assessment.

RESULTS

Utilizing a primary cffDNA screening strategy, the cost per patient was 1017 US$. With a traditional screening protocol using free β-hCG, PAPP-A and NT assessment as part of a hybrid screening strategy, a contingent strategy with a 1/300 cut-off and a contingent strategy with a 1/1000 cut-off, the cost per patient was 474, 430 and 409 US$, respectively. Findings were similar using the other traditional screening protocols. Marginal cost per viable case detected for the primary screening strategy as compared to the other strategies was 3-16 times greater than the cost of care for a missed case.

CONCLUSIONS

Primary cffDNA screening is not currently a cost-effective strategy. The contingent strategy was the lowest-cost alternative, especially with a risk cut-off of 1/1000. The hybrid strategy, although less costly than primary cffDNA screening, was more costly than the contingent strategy.