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

Prenatal visualization of the fetal uterus in routine 2D ultrasound examination

OBJECTIVE

To establish a new technique to easily identify the fetal cervix-uterus complex in normal female fetuses from 20 to 40 weeks of gestation.

MATERIAL AND METHODS

The study was performed in routine examination in normal fetuses by two observers. Twenty-five consecutive cases per gestational week were assessed between 20 and 40 weeks. The same plane of the bladder used in the assessment of the umbilical arteries was used. In this transverse view of the fetal pelvis different structures can be identified from front to back: the bladder, the bowel and the vertebral body. If the uterus is present, it can be seen between the bladder and the rectum, as a round structure pushing the posterior bladder wall. The echogenicity changes as the uterus develops and increases its size. Voluson E10 ultrasound device (GEHealthcare Ultrasound®, Zipf, Austria) equipped with an RM6Cprobe was utilized.

RESULTS

Successful identification of the cervix-uterus complex was possible overall in 83.4% of cases, reaching more than 93% from 31 weeks onwards. There was a rapid growth of the cervix-uterus complex after 26 weeks, and in the third trimester appears as a solid round structure behind the fetal bladder. Reproducibility analysis showed agreement between 2 observers in 92% of cases.

CONCLUSION

Identification of the uterus and cervix complex is possible from 20 weeks, although it is easier at the end of gestation. This reproducible technique allows the anatomical study of normal female fetuses and the visualization of kidney malformations and disorders of sexual development.

Systematic Review of Accuracy Differences in NIPT Methods for Common Aneuploidy Screening

Background/Objectives: Non-invasive prenatal testing (NIPT) has become a widely used method for screening common fetal aneuploidies due to its high sensitivity and specificity compared to traditional screening methods. With various NIPT technologies available, such as whole-genome sequencing (WGS), single nucleotide polymorphisms (SNPs), microarray, and rolling circle amplification (RCA), understanding the accuracy and reliability of each method is critical for clinical decision-making. However, comprehensive evaluations comparing the performance of these NIPT methods, especially in terms of predictive values for trisomy detection, remain limited. A systematic review of the difference in accuracy of the different NIPT methods used for common aneuploidy screening. Methods: A systematic review of former clinical studies using different NIPT methods, such as whole-genome sequencing (WGS), a targeted method of single nucleotide polymorphisms (SNPs), microarray and rolling circle amplification (RCA). We collected data from the PubMed, Embase, Web of Science, Scopus, clinicaltrials.gov, and Cochrane library from the last 20 years, between 2003 January and 2023 October, without any language, search filter or publication type restrictions. Results: Two authors selected twenty articles including twenty-one studies to perform the systematic review. In these studies, altogether 92,164 pregnant women were tested by genomics-based non-invasive prenatal testing (NIPT). We extracted data on true positive, false positive, false negative, and true negative values from each study, and calculated sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) from them. We collected data regarding trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13) detection from all studies. Conclusions: As a conclusion, for the detection of common fetal trisomies, different methods of NIPT perform similarly in terms of clinical sensitivity, specificity and NPV. However, the tests utilizing SNP and RCA had lower PPV values than other NIPT methods. Our research indicates all NIPT methods showed greater sensitivity for the detection of T21, above 97%, than traditional screening tests. For T18 detection, the targeted method with the microarray had a lower sensitivity compared to other tests. The SNP and the microarray-based test had high PPV, whilst the other tests, utilizing WGS, and the test with RCA had quite low PPV. Regarding T13 detection, all of the tests performed similarly in terms of clinical sensitivity, specificity, PPV, and NPV (with one exception-one of the tests using WGS had lower PPV). According to these results, there was no significant difference between the methods of NIPT, such as WGS, SNPs, microarray, and RCA, used to detect common trisomies, but the variation in PPV underlines the importance of invasive tests to derive positive NIPT results. We suggest that NIPT combined with US screening for structural abnormalities could further improve the utility of the non-invasive tests in pregnancy. This is the first independent systematic review into the efficacy of the different NIPT methods.

Towards a Responsible Implementation of NIPT as a First-Tier Test in Canada: Decision-Makers' Perspectives

OBJECTIVE

To explore decision makers' perspectives on the conditions for a responsible implementation of non-invasive prenatal testing (NIPT) as a first-tier test in Canadian provinces' healthcare systems.

METHOD

A qualitative study was conducted with 16 Canadian decision makers who were interviewed between February 2021 and July 2022. After anonymization and transcription, interviews were coded inductively using thematic analysis.

RESULTS

Our interviews showed the complexity of the decision making environment regarding prenatal screening funding. Participants agreed that NIPT is superior to maternal serum screening as a first-tier test, but they also recognized that first-tier NIPT has limits and barriers. They described the following conditions for its responsible implementation: (1) need for time and evidence; (2) taking stakeholders' perspectives into account; (3) limit costs for the healthcare system; (4) ensure appropriate logistical conditions and harmonize the test offer; (5) ensure appropriate clinical services; (6) ensure informed consent; (7) ensure the test is presented as an individual choice to avoid eugenic concerns.

CONCLUSION

Multiple barriers and issues need to be addressed before moving NIPT from second- to first-tier. Decision makers' perspectives should be contrasted with those of other important stakeholders, including pregnant people, disability advocates and healthcare professionals.

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.

Improved contingent screening strategy increased trisomy 21 detection rate in the second trimester

PURPOSE

This study aimed to establish suitable threshold values for biochemical indicators in low-risk pregnant women who underwent second trimester screening and design strategies for consecutive prenatal testing to increase trisomy 21 detection.

METHODS

This study examined singleton pregnant women who underwent double, triple, or quadruple screening in the second trimester over six years. To obtain adequate detection efficiency for low-risk pregnancies, threshold values for serum biochemical indicators were established, and a cost-effectiveness assessment of the improved contingent screening strategy was conducted.

RESULTS

Participants were included in serum double- (n = 88,550), triple- (n = 29,991), and quadruple-screening (n = 15,004) groups. Threshold values were defined as having a free beta subunit of human chorionic gonadotropin (free β-hCG) multiple of the median (MoM) ≥ 2.50, alpha-fetoprotein (AFP) MoM ≤ 0.50, or unconjugated estriol (uE3) MoM ≤ 0.70 for low risk. Low-risk pregnancies, comprising 1.35% (988/73,183), 4.45% (1,171/26,286), and 11.91% (1,559/13,085) of the double-, triple-, and quadruple-screening groups, respectively, underwent further non-invasive prenatal screening. In the double-, triple-, and quadruple-screening groups, we detected 11.76% (2/17), 40.00% (2/5), and 66.67% (2/3) of trisomy 21 cases with false negative results, respectively, with the overall detection rates of 85.00% (85/100), 90.63% (29/32), and 95.24% (20/21), respectively, and decreased ratio of overall costs of 5.26%, 16.63%, and 24.36%, respectively.

CONCLUSION

Utilizing threshold values of AFP, free β-hCG, and uE3 to trigger further non-invasive prenatal screening may increase trisomy 21 detection in pregnancies deemed low risk in the second trimester while reducing the overall costs of screening strategies.

Strategies to Detect Chromosomal Anomalies Not Identified by NIPT

INTRODUCTION

Genome-wide non-invasive prenatal testing (gwNIPT) has screening limitations for detectable chromosomal conditions and cannot detect microdeletions/microduplications (MD) or triploidy. Thickened nuchal translucency (NT) only detects around 10% of these cases.

METHODS

A 4-year retrospective study of singleton pregnancies undergoing first-line gwNIPT screening with subsequent CVS or amniocentesis. All MD cases, with or without gwNIPT screening, were also analyzed.

RESULTS

Among 919 pregnancies with gwNIPT and invasive testing, 338 had a single chromosomal abnormality, with 9 false negative gwNIPT results (2.9%) and 26 undetectable abnormalities (18 MD, 8 triploidy) (7.7%). Twelve cases had a dual chromosomal abnormality and 4 returned a low-risk gwNIPT result. Only three (9%) of the "missed cases" had a large NT and two of these also had a structural abnormality. Approximately 90% of chromosomal anomalies missed by gwNIPT were detected by invasive prenatal testing indicated by one or more of the following: failed NIPT (9%), low PAPP-A (12%), early growth restriction (37%) and structural anomalies at pre-NIPT, 13- or 20-week ultrasounds (51%).

CONCLUSION

Most chromosomal abnormalities missed or unable to be found by gwNIPT are detected due to growth restriction or structural anomalies, not an enlarged NT. Failed NIPT and low PAPP-A concentrations contributed to detection.

Enhancing Non-Invasive Prenatal Testing: A Novel Approach to Improve 45,X Prediction Accuracy

OBJECTIVE

Traditional non-invasive prenatal testing (NIPT) for sex chromosome aneuploidies (SCAs) has a higher risk of false positives, particularly for 45,X. This study introduces an innovative NIPT analysis pipeline to minimize false positives in 45,X screening.

METHODS

We included 39 cases from the NIPT records of 15,882 pregnancies, including 20 with 45,X and 19 controls, and performed standard NIPT and size-selection NIPT tests. Based on the two NIPT results, the Zs-score was used to determine aneuploidy status: > 3 indicated 45,X, and -3 to 3 suggested a negative result. We analyzed the change in the positive predictive value (PPV) of NIPT for 45,X.

RESULTS

By integrating data from two NIPT experiments and monitoring sex chromosome variations, the Zs of the control group ranged from -3 to 3, indicating no 45,X. In the NIPT-45,X group, 9 out of 20 cases had Zs > 3, whereas the remaining 11 cases had Zs between -3 and 3. The PPV of NIPT for 45,X improved from 25.00% (5/20) to 55.56% (5/9), and 73.33% (11/15) of the initial false positives were corrected by our method.

CONCLUSION

Our advanced analysis process significantly improved the PPV of NIPT for 45,X and reduced the incidence of false positives.

Amniocentesis and Risk of Fetal Loss in Dichorionic-Diamniotic Twin Pregnancy: A Case-Control Study

OBJECTIVE

There is a paucity of data regarding the risk of fetal loss due to invasive prenatal diagnosis in twins. The aim of the present study is to assess the rate of amniocentesis-related fetal loss in uncomplicated dichorionic-diamniotic (DCDA) twin pregnancies.

METHODS

Retrospective observational case-control study. DCDA twin pregnancies undergoing amniocentesis between January 2010 and December 2023 formed the case group. The control group comprised counterparts who did not undergo amniocentesis. The primary outcome of the study was procedure-related fetal loss. Secondary outcomes were miscarriage rate, overall fetal loss and gestational age at birth.

RESULTS

Our dataset included 220 and 662 women in the case and control groups, respectively. No difference in the primary outcome was found: procedure-related fetal loss of one fetus was 0.9% in the case group and 1.1% in the control group, and of both fetuses it was 0.5% in both groups (p = 0.982). No difference was found in secondary outcomes: the fetal loss rate of one fetus was 1.8% in the case group and 2.1% in the control group, while that of both fetuses it was 0.5% and 0.8% respectively (p = 0.853). Multivariate analysis confirmed the nonsignificant effect of amniocentesis on the risk of fetal loss.

CONCLUSION

Amniocentesis does not seem to increase the risk of fetal loss in uncomplicated DCDA twin pregnancies above the baseline risk of loss among twin gestations.

Bibliometric Analysis of Publications on Prenatal Genetic Screening Using Cell-Free DNA

Prenatal genetic testing plays a vital role in the early detection of fetal chromosomal abnormalities, with cell-free DNA (cfDNA) testing emerging as a highly accurate noninvasive screening method. By analyzing fetal DNA fragments in maternal plasma, cfDNA-based tests have significantly improved the detection of conditions such as trisomies.  Bibliometric analysis is a quantitative research method used to evaluate publication trends, citation patterns, and research impact within a specific scientific field. By analyzing bibliographic data, it provides insights into scholarly productivity, influential works, and collaboration networks, helping to identify key developments and emerging research areas. This bibliometric analysis provides a comprehensive overview of publication patterns and impacts in the field of prenatal genetic screening with cfDNA between 1991 and 2024. This study examined research articles and reviews on cfDNA used in prenatal genetic screening in English-language literature published between 1991 and May 1, 2024. The study analyzed various parameters, including top published institutions, countries, journals, citations, and funding organizations. Data was collected from the Web of Science bibliometric database using Medical Subject Headings (MeSH) keywords related to the research topic and gathered for analyzing publications and citations. VOSviewer (Centre for Science and Technology Studies (CWTS), Leiden University, the Netherlands) was used for co-authorship among top published organizations and countries and for keyword analyses. The study included 2272 publications on cfDNA revealing a diverse range of topics, with chromosome disorders being the most common. The majority of publications in the literature were published in journals indexed in the Science Citation Index Expanded (SCIE). The top five countries in global research contributions were the United States, China, England, Italy, and the Netherlands. The top organizations/universities contributing to these publications included the Chinese University of Hong Kong, BGI Shenzhen, Baylor College of Medicine, and Tufts University. Keyword analysis revealed a vast array of keywords, with "prenatal diagnosis" dominating the discourse. Top journals on cfDNA publications include Prenatal Diagnosis (269 publications), Clinical Chemistry (78 publications), and the American Journal of Obstetrics and Gynecology (72 publications), making them the leading platforms for research dissemination in this field. This bibliometric analysis highlights the growing impact of cfDNA-based prenatal genetic screening, revealing key contributors, influential studies, and research trends shaping the field. The findings underscore the significant role of cfDNA technology in improving noninvasive prenatal testing and guiding future research directions in this domain.

Chromosomal Mosaicism in the Placenta

The clinical implications of placental chromosomal mosaicism can be challenging for patients and health care providers. Key considerations include the specific characteristics of the chromosomal abnormality (such as size, gene content, and copy number), the timing of the mosaicism's onset during embryogenesis or fetal development, the types of tissues involved, and the level of mosaicism (the ratio of normal to abnormal cells within those tissues). Genetic counseling can help inform patients about the chances of having a live-born child with a chromosomal abnormality. Each case requires individual assessment to provide accurate guidance. This chapter will explore the clinical implications of detecting mosaicism at 3 critical diagnostic stages: (1) chorionic villus sampling (CVS); (2) amniocentesis; and (3) cell-free DNA (cfDNA) testing.

Factors, pregnancy outcomes, and management associated with non-reportable results in prenatal cell-free DNA testing

PURPOSE

To offer more effective strategies by classification of non-reportable results for physicians to manage those pregnancies.

METHODS

From July 2022 to May 2024, a total of 14,073 prenatal cell-free DNA (cfDNA) tests were performed by massively parallel sequencing (MPS) in our genetic laboratory and 52 cases received non-reportable results caused by different reasons. Chi-square analysis and logistic regression analysis were used to analyze the risk factors contributing to non-reportable results. The redraw test results and the pregnancy outcomes were collected and analyzed.

RESULTS

Overall, 52 (0.37%) of 14,073 pregnant women had non-reportable cfDNA testing results after the first draw. Multivariate logistic regression analysis revealed that pregnancies conceived by in vitro fertilization (IVF) (OR = 2.42, 95% CI 1.08-5.42, P = 0.03) and heparin use (OR = 7.04, 95% CI 2.40-20.62, P < 0.001) were independent factors for non-reportable cfDNA test results. In 52 cases with non-reportable results, 27 (51.92%) cases had borderline Z scores, 15 (28.85%) cases had a low fetal fraction (< 4.0%), 5 (9.62%) cases indicated multiple chromosomal aberrations (MCA, ≥ 4), and 5 (9.62%) cases had data fluctuation in sex chromosomes. All 52 (100%) cases chose to have a redraw test. The overall success rate of redraw test was 65.38%; however, cases with MCA mainly caused by cfDNA from uterine fibroids or maternal malignancies had relatively low success rate of redraw testing. Compared to pregnant women without risk factors, those with caution indications and with low fetal fraction (LFF) had a lower chance to obtain valid redraw testing results (100.00% vs 16.67%, P = 0.002). The abnormal conditions of perinatal women and infants were more frequent in the cases with non-reportable results after redraw tests (2.94% vs 14.71%, P = 0.027; 7.41% vs 14.81%, P = 0.038).

CONCLUSION

Repeated testing was not suitable for all cases with non-reportable results. Invasive prenatal diagnosis should be recommended for cases with MCA, cases with caution indications and with low fetal fraction for the first non-reportable results, cases with consecutive non-reportable cfDNA results. More attention should be paid to the cases with non-reportable cfDNA results, especially to the cases with non-reportable redraw testing results.

How Useful is Nuchal Translucency in Detecting Chromosomal Abnormalities Missed by Genome-Wide NIPT and What Measurement Threshold Should Be Used?

INTRODUCTION

Genome-wide non-invasive prenatal testing (gwNIPT) has screening limitations for detectable genetic conditions and cannot detect microdeletions/microduplications (MD) or triploidy. Nuchal translucency (NT) increases with gestation and with genetic or structural abnormalities. This study aims to determine the utility of NT measurement in detecting genetic abnormalities not identified by gwNIPT and the optimal NT threshold value.

METHODS

A 4-year retrospective study of singleton pregnancies undergoing first-line gwNIPT aneuploidy screening where invasive prenatal testing by CVS/or amniocentesis was subsequently undertaken. Population proportions for static and multiple of the median (MoM) NT cut-offs were derived from all 11-14 weeks ultrasound examinations.

RESULTS

Among 919 pregnancies with gwNIPT and invasive testing, 338 had a single genetic abnormality. There were 9 false negative GwNIPT results and a further 26 undetectable abnormalities (18 MD, 8 triploidy) in this cohort. Twelve had a dual chromosomal abnormality, four of which returned a low-risk gwNIPT. Thirty-three "missed cases" also had a 13-week scan, to which the various NT threshold values (3.0 mm, 1.6 MoM, 3.5 mm, and 1.9 MoM) were applied. In only 3 (9%) cases did the NT exceed 3.0 mm with similar detection rates (DR) for all higher cut-offs. Static and MoM-based NT cut-offs had similar positive predictive values (PPV).

CONCLUSION

Enlarged NT measurement is a poor predictor of genetic abnormalities not identified by gwNIPT. When applied, the fixed NT cut-off of 3.5 mm provides a low FPR with a similar DR to lower cut-off thresholds, resulting in a higher PPV.

Chatbot for patient education for prenatal aneuploidy testing: A multicenter randomized controlled trial

INTRODUCTION

Digital tools could assist obstetric providers by delivering information given increasing options for fetal aneuploidy screening.

PURPOSE

To determine the impact of a chatbot for pre-test education and counseling in low-risk pregnancies.

METHODS

Two sites participated in this randomized controlled trial. Patients in the intervention group used a chatbot prior to the provider visit, while patients in the control group only received education by the provider. The primary outcome was change in patient knowledge scores after provider education. Analysis was by intention to treat.

RESULTS

Overall, 258 women participated (n = 130; intervention and n = 128; control). Knowledge gain was significantly higher among patients using the chatbot (mean increase in correct answers [out of 20]: +4.1 vs +1.9, p < 0.001). Both groups reported high satisfaction, with no statistically significant difference between intervention and control groups (mean patient satisfaction [1-10]: 8.2 vs 8.5 respectively, p = 0.35). Providers also reported high satisfaction scores with no significant difference between intervention and control groups (mean provider satisfaction [1 - 10]: 8.7 vs 8.4 respectively, p = 0.13).

CONCLUSIONS

Pre-test education via a chatbot can increase patient knowledge of prenatal testing choices, with high patient and provider satisfaction.

Performance of cell free DNA as a screening tool based on the results of first trimester screening

The advent of non-invasive prenatal testing (NIPT) in the screening of fetal abnormalities has optimized prenatal care and decreased the rate of invasive diagnostic tests. In this retrospective descriptive study, we began with 1874 singleton pregnancies. After exclusion of some cases, the study cohort ended up with 1674 cases. We analyzed the performance of NIPT based on the results of first trimester screening (FTS) using serum screening combined with NT. The cases were also compared to diagnostic testing/pregnancy outcomes. Notably, in the subgroup with FTS risk < 1000, NIPT was reported to be normal in all cases with no false negative results. In the risk group of 1/300-1/1000, NIPT could detect all trisomy 21 cases with one false positive result. Moreover, in the risk group of 1/11 - 1/300, NIPT could detect all cases of trisomy 21, 13 and 18 with low false positive rate. However, the false positive rate for sex chromosomal abnormalities was high. Taken together, the current study confirms the applicability of NIPT as a tool for detection of fetal trisomies with high sensitivity and specificity. Yet, the high rate of false positive results for sex chromosome abnormalities should be considered in the interpretation of the results.

Implementing non-invasive prenatal testing in a national screening program: Lessons learned from the TRIDENT studies

The Dutch NIPT Consortium, a multidisciplinary collaboration of stakeholders in prenatal care initiated and launched the TRIDENT studies. The goal of the TRIDENT studies was to implement non-invasive prenatal testing (NIPT), first as a contingent (second-tier) and later as a first-tier test, and to evaluate this implementation. This paper describes how NIPT can be successfully implemented in a country or state. Important factors include the significance of forming a consortium and encouraging cooperation among relevant stakeholders, appropriate training for obstetric care professionals, and taking into account the perspectives of pregnant women when implementing prenatal tests. We describe the advantages of high sensitivity and specificity when comparing contingent NIPT with first-tier NIPT. This paper emphasizes the value of pre- and post-test counselling and the requirement for a standardized method of information delivery and value clarification, to assist couples in decision making for prenatal screening.

False-Positive Diagnosis of Congenital Heart Defects at First-Trimester Ultrasound: An Italian Multicentric Study

Objective. Our objective was to assess the proportion of false-positive CHD cases at the first-trimester evaluation of the fetal heart, performed by experienced operators. Methods. This multicenter retrospective study included of pregnant women with suspicion of CHDs during first-trimester screening for aneuploidies. In all cases, the fetal heart assessments were performed by obstetricians with extensive experience in first-trimester scanning, following an extended protocol proposed by SIEOG national guidelines, which included an axial view of the fetal abdomen and chest to assess visceral situs and evaluation of the four-chamber view (4CV) and three-vessel trachea view (3VTV) with color Doppler. In all suspected cases, fetal echocardiography was offered within 16 and/or at 19-22 weeks' gestation. Results. From a population of 4300 fetuses, 46 CHDs were suspected. Twenty-four cases were excluded from this analysis because the parents opted for early termination of the pregnancies due to associated structural and/or genetic anomalies. For the remaining 22, echocardiography was performed by 16 weeks in 14 cases (64%) and after 16 weeks in 8 cases. In 19 cases (86.4%), a fetal cardiologist confirmed the presence of a CHD. In three cases (13%), the cardiac anatomy was found to be normal at the fetal echocardiography and postnatally. Conclusions. This study shows that the proportion of false-positive cases at the first-trimester ultrasound examination of the fetal heart, performed by experienced operators, may carry a higher risk of false-positive diagnosis than expected. Therefore, this issue must be discussed in instances where a CHD is suspected at the first-trimester screening.

Guideline No. 456: Prenatal Screening for Fetal Chromosomal Anomalies

OBJECTIVE

To review the available prenatal aneuploidy screening options and to provide updated clinical guidelines for reproductive care providers.

TARGET POPULATION

All pregnant persons receiving counselling and providing informed consent for prenatal screening.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline should increase clinician competency to offer counselling for prenatal screening options and provide appropriate interventions. Given the variety of available options for prenatal screening with different performance, cost, and availability across Canada, appropriate counselling is of paramount importance to offer the best individual choice to Canadian pregnant persons. Prenatal screening may cause anxiety, and the decisions about prenatal diagnostic procedures are complex given the potential risk of fetal loss.

EVIDENCE

Published literature was retrieved through searches of Medline, PubMed, and the Cochrane Library in and prior to July 2023, using an appropriate controlled vocabulary (prenatal diagnosis, amniocentesis, chorionic villi sampling, non-invasive prenatal screening) and key words (prenatal screening, prenatal genetic counselling). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies written in English and published from January 1995 to July 2023.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations).

INTENDED AUDIENCE

Health care providers involved in prenatal screening, including general practitioners, obstetricians, midwives, maternal-fetal medicine specialists, geneticists, and radiologists.

SOCIAL MEDIA ABSTRACT

Non-invasive prenatal screening is the most accurate method for detecting major aneuploidies. It is not universally available in the public health system and has some limitations.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Clinical Applications of Fetal Cell-Free DNA: State of the Science

Advances in technology have correlated with expanding prenatal genetic testing options for pregnant people. Leading medical organizations recommend cell-free DNA as the most sensitive screening test for trisomies 13, 18, and 21, as well as for fetal sex chromosome aneuploidies. The commercially available testing options go beyond these recommended tests, and prenatal care professionals should be familiar with the tests that their patients may choose despite being beyond the scope of current medical recommendations. This article explains updates in cell-free DNA technology and clinical considerations for prenatal care professionals, recognizing that this is a rapidly changing field of science and health care.

Massive parallel sequencing-based non-invasive prenatal test (NIPT) identifies aberrations on chromosome 13

OBJECTIVE

We report data of non-invasive prenatal testing (NIPT) at Uppsala University Hospital between 2017-2022. Furthermore, we illustrate the potential capacity of massive parallel sequencing-based NIPT beyond identification of common trisomies.

METHODS

Maternal blood samples were analyzed using the Verifi NIPT or VeriSeq NIPT assays. Diagnostic testing, performed on amniotic fluid samples, included QF-PCR, microarray (SNP-array) and metaphase FISH.

RESULTS

Among 4532 NIPT tests performed between 2017-2022, 125 samples (2.76%) showed increased risk for trisomies 13, 18, 21 and sex chromosome aneuploidy. For three patients with normal NIPT result further microarray indicated other types of chromosomal rearrangement which were not analyzed by NIPT. For another patient (case 1) the Verifi NIPT indicated trisomy 13. Fetal fraction (FF) was estimated to be 10%. Confirmatory microarray detected a segmental duplication on chromosome 13, as well as a terminal duplication and a terminal deletion on chromosome 10. A complex karyotype was observed in the fetus with metaphase FISH. In the second case the VeriSeq NIPT indicated trisomy 13. FF was estimated to be 11%. Confirmatory microarray detected a mosaicism of trisomy 13 in 30 % of cells.

CONCLUSION

This study illustrates detection of peculiar abnormalities of chromosome 13 and supports potential to screen copy number variations with genome-wide NIPT.

A review of neurogenetics in fetal and neonatal clinical medicine

This review of neurogenetics serves as a primer for clinicians practicing in fetal-neonatal medicine. The review provides an update on neurogenetics, understanding the language of genetics, genetic testing approaches, and interpretation of genetic test results. Common examples of neurogenetic disease in fetal-neonatal medicine are used to enhance basic concepts. The results of genetic testing and their implications for patients and families are outlined. Genetics is becoming foundational to clinical practice across specialties. The advances are improving the speed of diagnosis, facilitating early treatments, and improving outcomes in neurogenetic disorders. A basic understanding of genetics is foundational to appropriate clinical-decision making and interpretation of those results to describe common fetal-neonatal neurological phenotypes.

Cell-Free Fetal DNA for Prenatal Screening of Aneuploidies and Autosomal Trisomies: A Systematic Review

Aim: This study was aimed at comparing the positive predictive value of a high-risk cell-free fetal DNA test result for sex chromosome aneuploidies (45,X0, 47,XXX, 47,XXY, and 47,XYY) and autosomal trisomies (T21, T18, and T13) with confirmatory tests in singleton pregnancies. Additionally, we identify the main reason for discordant and inconclusive results. Methods: PubMed, Web of Science, and Scopus were searched from 2017 for primary research articles on cell-free fetal DNA testing of autosomal trisomies and sex chromosome aneuploidies in singleton pregnancies. The methodological characteristics and the statistical results of the studies were collected, and the risk of bias was assessed. Results: Fourteen studies were included. Among the autosomal trisomies, T21 had the highest, whereas T13 showed the lowest positive predictive values. As for the sex chromosome aneuploidies, the lowest values were found with 45,X0. Although discordant and inconclusive results were reported inconsistently, false positives were mainly caused by mosaicism, and inconclusive results were mostly secondary to a low fetal DNA fraction. Conclusion: Cell-free fetal DNA is a reliable screening tool for autosomal trisomies. It is also useful for sex chromosome aneuploidies, although the positive predictive values are lower. A positive screening result should be followed with a confirmatory test.

Combined first-trimester screening and invasive diagnostics for atypical chromosomal aberrations: Danish nationwide study of prenatal profiles and detection compared with NIPT

OBJECTIVES

Our aim was to examine the prenatal profiles of pregnancies affected by an atypical chromosomal aberration, focusing on pathogenic copy-number variants (pCNVs). We also wanted to quantify the performance of combined first-trimester screening (cFTS) and a second-trimester anomaly scan in detecting these aberrations. Finally, we aimed to estimate the consequences of a policy of using non-invasive prenatal testing (NIPT) rather than invasive testing with chromosomal microarray analysis (CMA) to manage pregnancies identified as high risk by cFTS.

METHODS

This was a retrospective review of the Danish Fetal Medicine Database of all pregnant women who underwent cFTS and a risk assessment for trisomy 21 between 1 January 2008 and 31 December 2018. Chromosomal aberrations diagnosed prenatally, postnatally or from fetal tissue following pregnancy loss or termination of pregnancy were identified. Chromosomal aberrations were grouped into one of six categories: triploidy; common trisomy (13, 18 or 21); monosomy X; other sex-chromosome aberration (SCA); pCNV; and rare autosomal trisomy (RAT) or mosaicism. The prevalence of each aberration category was stratified by the individual cFTS markers and trisomy 21 risk estimate, and the size of each pCNV diagnosed by CMA was calculated.

RESULTS

We retrieved data on 565 708 pregnancies, of which 3982 (0.70%) were diagnosed with a fetal chromosomal aberration. cFTS identified 87% of the common trisomies, but it also performed well in identifying triploidies (86%), monosomy X (92%), atypical SCAs (58%) and RATs or mosaicisms (70%). pCNVs comprised 27% (n = 1091) of the chromosomal aberrations diagnosed overall, and the prevalence increased during the study period, as prenatal CMA was increasingly being performed. In pregnancies with a maternal age < 30 years, nuchal translucency (NT) thickness ≤ 95th centile, pregnancy-associated plasma protein-A (PAPP-A) ≥ 1 multiple of the median, or trisomy 21 risk of ≤ 1 in 1000, the prevalence of pCNVs exceeded significantly the prevalence of trisomies 21, 18 and 13. Pregnancies affected by a pCNV had significantly increased NT and decreased levels of the maternal biomarkers PAPP-A and β-human chorionic gonadotropin compared with unaffected pregnancies. However, only 23% of these pregnancies screened positive on cFTS and 51% of pCNVs were not detected until after birth. Among high-risk pregnancies, pCNVs comprised 14% of diagnosed aberrations, and when other atypical aberrations were considered, conventional NIPT (screening for trisomies 21, 18 and 13 and monosomy X) would miss 27% of all pathogenic aberrations diagnosed from invasive testing following a high-risk cFTS result. Thus, 1 in 26 pregnancies at high risk following cFTS would be affected by a chromosomal aberration despite a normal result from conventional NIPT. In a contingent screening model using NIPT for the 'intermediate'-risk group (trisomy 21 risk of 1 in 100-299), 50% of the aberrations would be missed. In our cohort, 79% of the pCNVs diagnosed were < 5Mb and therefore not detectable using current forms of 'genome-wide' NIPT.

CONCLUSIONS

As a by-product of screening for trisomies 21, 18 and 13, most triploidies and the majority of atypical SCAs, RATs and mosaicisms are detected before birth. However, only 23% of pCNVs are associated with a high-risk result according to cFTS and only half are diagnosed before birth. Replacing invasive testing with NIPT for high-risk pregnancies would substantially decrease the first-trimester detection of pathogenic chromosomal anomalies. © 2024 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Relation of the intense physical exercise and asprosin concentrations in type 2 diabetic rats

AIM

Asprosin, a protein hormone, is released by unilocular adipocytes in reaction to low blood sugar. We aimed to examine how exercise affects asprosin hormone levels and associated organs, including the liver and pancreas, in diabetes.

METHODS

Twenty-one male Wistar albino rats were firstly allocated into two main groups: control (n = 7) and diabetes (n = 14). Then, the diabetes group was further separated into two subgroups: sedentary (n = 7) and exercise (n = 7). The exercise group participated in a swimming training regimen (30 min/daily, six weeks). Serum levels of asprosin and various other biochemical parameters were evaluated through commercial ELISA kits. The liver was analyzed histopathologically, and pancreatic islet cells were examined for Cas-3 immune expression.

RESULTS

Asprosin and total oxidant status decreased significantly in the exercise diabetic subgroup (p < 0.05). Glucose, insulin, creatinine, IL-6, and HomaIR concentrations decreased slightly with exercise (p > 0.05). Liver tissue injury scores and Cas-3 immune expression in pancreas islet cells decreased in exercise diabetic rats.

CONCLUSIONS

Reducing asprosin may lower glucose, insulin, and HOMA-IR. Physical activity decreases asprosin and total oxidative status, fostering anti-apoptosis and tissue healing in diabetes, potentially enhancing health. Monitoring asprosin levels offers insights into diabetes progression. Our findings imply that asprosin can be a therapeutic target for diabetes.

Uterine fibroids and non-informative cell-free DNA screening results

OBJECTIVE

Uterine fibroids are monoclonal tumors, which are often genetically abnormal and associated with false-positive genome-wide cell-free DNA (cfDNA) screening results, particularly when large. It is plausible that fibroids may also increase the risk of cfDNA failure by affecting fetal fraction or due to their genetic anomalies confounding cfDNA algorithms. We aimed to investigate a possible association between fibroids and cfDNA non-informative results.

METHODS

This was a retrospective cohort study of women undergoing cfDNA screening for fetal chromosomal abnormalities between 2013 and 2020, comparing pregnancies with vs without uterine fibroids recorded on any obstetric ultrasound before 24 weeks' gestation. Univariable and multivariable logistic regression models were used to investigate the association between fibroids and cfDNA failure, adjusting for gestational age, maternal age, weight and height at blood sampling, mode of conception, multiple gestation and test platform (chromosome-selective or genome-wide). Analyses were stratified according to the number of fibroids and total fibroid volume. The impact of fibroids on fetal fraction was assessed using linear regression, adjusting for the same covariates.

RESULTS

Among 19 818 pregnancies undergoing cfDNA screening, fibroids were reported in 2038 (10.28%) and cfDNA failure at the first screening attempt occurred in 228 (1.15%) pregnancies. Non-informative results occurred in 1.96% of pregnancies with fibroids and 1.06% of pregnancies without fibroids (adjusted odds ratio (aOR), 2.40 (95% CI, 1.65-3.48)). The risk of failure in the first screening attempt increased progressively with the number of fibroids (aOR, 5.05 (95% CI, 2.29-11.13) in women with four or more fibroids) and total fibroid volume, with greater than a 5-fold and 14-fold increase in risk among women with fibroid volumes of 100.1-400 mL (aOR, 5.52 (95% CI, 2.30-13.25)) and > 400 mL (aOR, 14.80 (95% CI, 4.50-48.69)), respectively. Although test failure was more common with chromosome-selective than genome-wide screening, fibroids similarly increased the risk of failure of both screening platforms. Compared to pregnancies without fibroids, those with fibroids had a fetal fraction on average 0.61% lower (adjusted mean difference, -0.61% (95% CI, -0.77% to -0.45%)).

CONCLUSION

Uterine fibroids are associated with lower fetal fraction and an increased risk of cfDNA screening failure. The strength of this association increases with increasing fibroid number and volume. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Extracted Plasma Cell-Free DNA Concentrations Are Elevated in Colic Patients with Systemic Inflammation

Colic is a common and potentially life-threatening condition in horses; in many cases, it remains challenging for clinicians to determine the cause, appropriate treatment, and prognosis. One approach that could improve patient care and outcomes is identification of novel diagnostic and prognostic biomarkers. Plasma cell-free DNA (cfDNA) is a biomarker that shows promise for characterizing disease severity and predicting survival in humans with acute abdominal pain or requiring emergency abdominal surgery. In horses, we recently determined that extracted plasma cfDNA concentrations are elevated in colic patients compared to healthy controls. For this current study, we hypothesized that extracted plasma cfDNA concentrations would be significantly higher in horses with strangulating or inflammatory colic lesions, in colic patients with systemic inflammatory response syndrome (SIRS), and in non-survivors. Cell-free DNA concentrations were measured in extracted plasma samples using a compact, portable Qubit fluorometer. Colic patients that met published criteria for equine SIRS had significantly higher median extracted plasma cfDNA compared to non-SIRS colic patients. There were no significant differences in extracted plasma cfDNA concentrations between other groups of interest. Our data offer early evidence that extracted plasma cfDNA concentration may provide information about systemic inflammation in colic patients, and additional research is warranted to expand on these findings.

Cell-free DNA test for fetal chromosomal abnormalities in multiple pregnancies

INTRODUCTION

This study aimed to report the screening performance of cell-free DNA (cfDNA) testing for chromosomal abnormalities in twins, triplets, and vanishing twin pregnancies.

MATERIAL AND METHODS

Data were obtained from pregnant women with a multiple pregnancy or a vanishing twin pregnancy at ≥10 weeks' gestation who requested self-financed cfDNA testing between May 2015 and December 2021. Those that had positive screening results had diagnostic confirmatory procedures after counseling and consent. The performance of screening of the cfDNA test was determined by calculating confirmation rate and combined false-positive rate (cFPR).

RESULTS

Data from 292 women were included after exclusion of those lost to follow-up, with no-result on cfDNA testing, or had reductions. Of the 292 pregnancies, 10 (3.4%) were triplets, including no cases of trisomy 21 and trisomy 18; 249 (85.3%) were twins, including 3 cases of trisomy 21 and no cases of trisomy 18 and 13; and 33 (11.3%) were vanishing twins, including 3 cases of trisomy 21 and 1 case of trisomy 18. The median (IQR) maternal age was 34 years (31-37). For triplet pregnancies, the initial no-result rate was 10.3% (95% confidence interval [CI] 3.6-26.4), all with results after redraw. For twin pregnancies, the initial no-result rate was 12.9% (95% CI 9.6-17.0), and the no-result rate after redraw was 1.6% (95% CI 0.7-3.6). For vanishing twins, there were no cases with no-result. All triplets had low-risk cfDNA results. The confirmation rate for trisomy 21 was 100% with a FPR at 0% due to the small number of positive cases for twins. For vanishing twins, one high-risk case for trisomy 21 and the only high-risk case for trisomy 18 were confirmed with a cFPR of 8.3% (n = 2/24; 95% CI 2.3-25.9).

CONCLUSIONS

cfDNA testing in twin pregnancies has sufficient screening performance for trisomy 21 but the number of affected cases for other conditions is limited to draw any meaningful conclusion. The use of cfDNA testing in triplet pregnancies and vanishing twins remains an area for further research.

Low fetal fraction and adverse pregnancy outcomes- systematic review of the literature and metanalysis

PURPOSE

While cell-free DNA (cfDNA) screening has emerged as a screening modality for common aneuploidies, further research and several publications over the past decade suggested some correlation between the low concentrations of cfDNA and a number of pregnancy-related complications. The primary goal of this systematic review and meta-analysis was to assess the potential value of low-ff levels in the prediction of subsequent PE/PIH, GDM, SGA/FGR, and PTB. The meta-analysis results aim at summarizing the currently available literature data and determining the clinical relevance of this biochemical marker and the potential necessity for additional investigation of its utility in complications other than the detection of common aneuploidies.

METHODS

This systematic review and meta-analysis was designed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. It included all observational studies that reported low -ff levels after the performance of non-invasive prenatal testing (NIPT) as part of the screening for chromosomal abnormalities and their association with adverse pregnancy outcomes, namely the subsequent development of hypertensive disorders of pregnancy, gestational diabetes, preterm birth, and the detection of small for gestational age fetuses or growth-restricted fetuses. The Medline (1966-2041), Scopus (2004-2024), Clinicaltrials.gov (2008-2024), EMBASE (1980-2024), Cochrane Central Register of Controlled Trials CENTRAL (1999-2024) and Google Scholar (2004-2024) databases were used in our primary search along with the reference lists of electronically retrieved full-text papers. The date of our last search was set at February 29, 2024.

RESULTS

Our search identified 128 potentially relevant studies and,overall, 8 studies were included in the present systematic review that enrolled a total of 72,507 patients. Low ff of cfDNA cfDNA was positively associated with HDP (OR 1.66, 95% CI 1.34, 2.06, I-square test: 56%). Low ff of cfDNA was positively associated with GDM (OR 1.27, 95% CI 1.03, 1.56, I-square test: 76%). Furthermore, low ff levels were positively associated with SGA/FGR (OR 1.63, 95% CI 1.32, 2.03, I-square test: 0%). Low ff levels were positively correlated with the risk for PTB but the association did not manage to reach a statistical significant level (OR 1.22, 95% CI 0.89, 1.67, I-square test: 66%).

CONCLUSION

Our study suggests that low ff is associated with increased risk of adverse perinatal outcomes, including PE/PIH, GDM, and SGA/FGR. However, the relationship between ff and PTB remains unclear due to conflicting evidence. It should be emphasized that further research is needed to reveal the underlying mechanisms behind the association of low ff with adverse pregnancy outcomes and explore its potential role in an overall prenatal screening, which could potentially not be limited to detecting aneuploidies.

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.

Cell-Free DNA Analysis of Fetal Aneuploidies in Early Pregnancy Loss

Background: Products of conception samples are often collected and analyzed to try to determine the cause of an early pregnancy loss. However, sample collection may not always be possible, and maternal cell contamination and culture failure can affect the analysis. Cell-free DNA-based analysis of a blood sample could be used as an alternative method in early pregnancy loss cases to detect if aneuploidies were present in the fetus. Methods: In this prospective study, blood samples from early pregnancy loss patients were analyzed for the presence of fetal aneuploidies using a modified version of a noninvasive prenatal testing assay for cell-free DNA analysis. Results from cell-free DNA analysis were compared against the gold standard, microarray analysis of products of conception samples. This study was registered with ClinicalTrials.gov, identifier: NCT04935138. Results: Of the 76 patient samples included in the final study cohort, 11 were excluded from performance calculations. The 65 patient samples included in the final analysis included 49 with an abnormal microarray result and 16 with a normal microarray result. Based on results from these 65 samples, the study found that genome-wide cell-free DNA analysis had a sensitivity of 73.5% with a specificity of 100% for the detection of fetal aneuploidies in early pregnancy loss cases. Conclusions: This prospective study provides further support for the utility of cell-free DNA analysis in detecting fetal aneuploidies in early pregnancy loss cases. This approach could allow for a noninvasive method of investigating the etiology of miscarriages to be made available clinically.

Early Non-Invasive Prenatal Testing at 6-9 Weeks of Gestation

Non-invasive prenatal testing (NIPT) is usually performed beyond 10 weeks of gestation, because earlier in pregnancy, the fetal fraction is low, resulting in failure to obtain reliable results. This study aimed to evaluate the clinical performance of NIPT earlier in pregnancy using a method for cell-free DNA (cfDNA) analysis that eliminates the need for polymerase chain reaction (PCR), DNA sequencing, or microarrays (Vanadis® system, PerkinElmer, Waltham, MA, USA). Cell-free DNA was extracted from the maternal plasma of 30 singleton pregnancies at 6-9 weeks of gestation (group 1) and at 11-14 weeks of gestation of the same patients (group 2). The mean crown-rump length (CRL) and gestational age in group A was 16.12 mm and that in group B was 61.45 mm. In group A, results were obtained in all, but one, cases (97%). From the remaining pregnancies, one miscarried at 8 weeks and, therefore, the follow-up NIPT at 12 weeks could not be performed. The fetal sex was diagnosed correctly in the 28 cases that had a successful early test, and the results were in accordance with the examination at 12 weeks. There were no cases of aneuploidies and disomy was diagnosed correctly in all. The "Vanadis" prenatal NIPT assay can successfully be used early during the first trimester at 6-9 weeks of gestation (early NIPT) to identify the fetal sex. Further studies are needed to explore the diagnostic potential for aneuploidies.

Cell-free DNA screening for common autosomal trisomies using rolling-circle replication in twin pregnancies

OBJECTIVE

To evaluate the performance of prenatal screening for common autosomal trisomies in twin pregnancies through the use of rolling-circle replication (RCR)-cfDNA as a first-tier test.

METHOD

Prospective multicenter study. Women who underwent prenatal screening for trisomy (T) 21, 18 and 13 between January 2019 and March 2022 in twin pregnancies were included. Patients were included in two centers. The primary endpoint was the rate of no-call results in women who received prenatal screening for common autosomal trisomies by RCR-cfDNA at the first attempt, compared to that in prospectively collected samples from 16,382 singleton pregnancies. The secondary endpoints were the performance indices of the RCR-cfDNA.

RESULTS

862 twin pregnancies underwent screening for T21, T18 and T13 by RCR-cfDNA testing at 10-33 weeks' gestation. The RCR-cfDNA tests provided a no-call result from the first sample obtained from the patients in 107 (0.7%) singleton and 17 (2.0%) twin pregnancies. Multivariable regression analysis demonstrated that significant independent predictors of test failure were twin pregnancy and in vitro fertilization conception. All cases of T21 (n = 20/862; 2.3%), T18 (n = 4/862; 0.5%) and T13 (n = 1/862; 0.1%) were correctly detected by RCR-cfDNA (respectively, 20, 4 and 1 cases). Sensitivity was 100% (95% CI, 83.1%-100%), 100% (95% CI 39.8%-100%) and 100% (95% CI 2.5%-100%) for T21, T18 and T13, respectively, in twin pregnancies.

CONCLUSION

The RCR-cfDNA test appears to have good accuracy with a low rate of no-call results in a cohort of twin pregnancies for the detection of the most frequent autosomal trisomies.

Very elevated hCGβ (≥10 multiple of the median) in maternal marker screening for Down syndrome: Frequency, etiologies, outcomes, and guidelines

AIM

This aim of this study was to detail maternal and fetal anomalies observed on a national scale in a large French cohort of patients presenting high hCG values (≥10 multiple of the median [MoM]) at Down syndrome screening in order to define clear and optimal guidelines.

METHODS

This is a retrospective multicenter study based on a French annual database of all trisomy 21 screenings. Our study targeted and studied cases with hCG or hCGβ values ≥10 MoM. Complementary exams and outcomes were analyzed.

RESULTS

The calculated frequency was 0.05% for hCGβ ≥10 MoM in unselected patients. For this series of 289 cases, a complication of the pregnancy or a poor outcome was observed in 145 cases (51%) as follows: 96 (66%) cases of fetal disease, 23 (16%) of maternal disease, 5 (3.5%) of placental anomalies and 21 (14.5%) of systemic disease concerning mother, fetus and placenta.

CONCLUSION

This study establishes the frequency of hCG or hCGβ values ≥10 MoM, presents a flow chart that optimizes follow-up, and gives clear information for patients presenting with such abnormal values at trisomy 21 screening.

Fetal hemodynamics and placental histopathology in Down syndrome

OBJECTIVE

To evaluate the association between Doppler patterns in fetuses with Down syndrome (DS) and their placental histopathologic findings.

METHODS

A retrospective cross-sectional study was performed by collecting data from medical records of singleton pregnancies between January 2014 and January 2022, whose fetuses had a confirmed diagnosis of DS either prenatally or postnatally. Placental histopathology, maternal characteristics, and prenatal ultrasound (biometric parameters and umbilical artery [UA] Doppler) were evaluated.

RESULTS

Of 69 eligible pregnant women, 61 met the inclusion and exclusion criteria. In the sample, 15 fetuses had an estimated fetal weight < 10th percentile for gestational age (GA) and were considered small for gestational age (SGA). Thirty-eight fetuses had increased resistance on the UA Doppler. Histologic changes were detected in 100% of the placentas, the most common being delayed villous maturation, alterations associated with poor fetal vascular perfusion, and villous dysmorphism. More than 50% of the placentas showed alterations related to placental insufficiency. We did not observe a statistically significant association between UA Doppler examination and placental alterations. All placentas analyzed in the SGA subgroup showed findings compatible with placental insufficiency.

CONCLUSION

We found no statistically significant association between placental histopathologic findings and UA Doppler abnormalities in fetuses with DS. The placental alterations identified were delayed villous maturation, alterations associated with poor fetal vascular perfusion, and villous dysmorphism.

Test performance and clinical utility of expanded non-invasive prenatal test: Experience on 71,883 unselected routine cases from one single center

OBJECTIVE

The balance between benefits and risks of discordant outcomes makes the Genome-Wide Non-Invasive Prenatal Test (GW-NIPT) controversial. This study aims to evaluate performance and clinical utility in a wide cohort of unselected clinical cases from a single center when a standardized protocol is applied and integrated with a secondary algorithm for data interpretation.

METHOD

In 2 years, over 70,000 pregnant patients underwent GW-NIPT for fetal common trisomies, sex chromosome aneuploidies, rare autosomal aneuploidies, segmental abnormalities (CNVs ≥ 7 Mb) and microdeletions (CNVs < 7 Mb). All samples were uniformly processed with Veriseq NIPT Solution v2 and analyzed using all data metrics along with a home-made algorithm for sequencing data analysis. Results were retrospectively reviewed for clinical outcomes.

RESULTS

Among 71,883 eligible cases including twin pregnancies, 1011 (1.4%) received a positive result and 781 were confirmed by invasive prenatal diagnosis. Clinical sensitivity ranged from 99.65% for common trisomy (T21, T18, T13) to 83.33% for microdeletions, while specificity remained high (99.98%) for each class of fetal abnormalities detected.

CONCLUSIONS

Integrating a standardized protocol with an internal algorithm allowed discordant results to be reduced, yielding high accuracy. Observed reliability in detecting genome-wide chromosomal conditions reinforced the expanded NIPT utility in clinical practice.

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.

Non-invasive cell-free DNA prenatal screening for trisomy 21 as part of primary screening strategy in twin pregnancy

OBJECTIVES

The performance of non-invasive prenatal screening using cell-free DNA testing of maternal blood in twin pregnancy is underevaluated, while serum marker-based strategies yield poor results. This study aimed to assess the performance of non-invasive prenatal screening for trisomy 21 in twin pregnancy as a first-tier test. Secondary objectives were to assess its failure rate and factors associated with failure.

METHODS

This retrospective cohort study included twin pregnancies in which non-invasive prenatal screening using cell-free DNA was performed as the primary screening strategy between May 2017 and October 2019. We used the NIPT VeriSeq® test for in-vitro diagnosis and set a fetal fraction cut-off of 4% for monochorionic pregnancies and 8% for dichorionic ones. Clinical data and pregnancy outcome were collected from physicians or midwives via a questionnaire or were retrieved directly on-site. We calculated the performance of non-invasive cell-free DNA screening for trisomy 21, analyzed its failure rate and assessed potentially associated factors.

RESULTS

Among 1885 twin pregnancies with follow-up, there were six (0.32%) confirmed cases of trisomy 21. The sensitivity of non-invasive prenatal screening for trisomy 21 was 100% (95% CI, 54.1-100%) and the false-positive rate was 0.23% (95% CI, 0.06-0.59%). The primary failure rate was 4.6%, with 4.0% being due to insufficient fetal fraction. A successful result was obtained for 65.4% of women who underwent a new blood draw, reducing the overall failure rate to 2.8%. Maternal body mass index, gestational age at screening as well as chorionicity were significantly associated with the risk of failure.

CONCLUSION

This study provides further evidence of the high performance, at an extremely low false-positive rate, of non-invasive prenatal screening in twins as part of a primary screening strategy for trisomy 21. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Atypicality index as an add-on to combined first-trimester screening for chromosomal aberrations

OBJECTIVES

To compute a set of atypicality indices based on combined first-trimester screening (cFTS) markers and second-trimester estimated fetal weight (EFW), and to demonstrate their potential in identifying pregnancies at reduced or increased risk of chromosomal aberrations following a low-risk cFTS result.

METHODS

The atypicality index quantifies the unusualness of an individual set of measurements relative to a reference distribution and can be computed from any variables or measurements available. A score of 0% on the atypicality index represents the most typical profiles, while a score of 100% indicates the highest level of atypicality. From the Danish Fetal Medicine Database, we retrieved data on all pregnant women seen for cFTS in the Central Denmark Region between January 2008 and December 2018. All pregnancies with a cytogenetic or molecular analysis obtained prenatally, postnatally or following pregnancy loss or termination were identified. A first-trimester atypicality index (AcFTS) was computed based on nuchal translucency (NT) thickness, maternal serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A). Furthermore, a second-trimester index (AcFTS + EFW) was computed from cFTS markers and EFW from a routine second-trimester anomaly scan. All pregnancies were stratified into subgroups based on their atypicality levels and their cFTS risk estimates. The risk of chromosomal aberrations in each subgroup was then compared with the overall prevalence, and a graphical presentation of the multivariate measurement profiles was developed.

RESULTS

We retrieved data on 145 955 singleton pregnancies, of which 9824 (6.7%) were genetically examined. Overall, 1 in 122 (0.82% (95% CI, 0.77-0.87%)) of all pregnancies seen for cFTS were affected by a fetal chromosomal aberration, and in screen-negative pregnancies (cFTS trisomy 21 risk < 1 in 100 and/or trisomy 18/13 risk < 1 in 50), 0.41% (95% CI, 0.38-0.44%) were affected. In screen-negative pregnancies with a typical first-trimester profile (AcFTS < 80%), the risk of chromosomal aberrations was significantly reduced (0.28%) compared with the overall risk. The risk of chromosomal aberrations increased with higher atypicality index to 0.49% (AcFTS [80-90%)), 1.52% (AcFTS [90-99%)) and 4.44% (AcFTS ≥ 99%) and was significantly increased in the two most atypical subgroups. The same applied for the second-trimester atypicality index, with risks of chromosomal aberrations of 0.76% and 4.16% in the two most atypical subgroups (AcFTS + EFW [90-99%) and AcFTS + EFW ≥ 99%, respectively).

CONCLUSIONS

As an add-on to cFTS, the atypicality index identifies women with typical measurement profiles, which may provide reassurance, whereas atypical profiles may warrant specialist referral and further investigation. In pregnancies identified as low risk on cFTS but with a highly atypical distribution of NT, PAPP-A and β-hCG, the risk of a chromosomal aberration is substantially increased. The atypicality index optimizes the interpretation of pre-existing prenatal screening profiles and is not limited to cFTS markers or EFW. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

First-Trimester Ultrasound Screening in Routine Obstetric Practice

Technologic advances and ultrasonographer-physician experience in fetal imaging have led to significant improvements in our ability to distinguish between normal and abnormal fetal structural development in the latter part of the first trimester. As a critical component of pregnancy care, assessment of fetal anatomy at the end of the first trimester with a standardized imaging protocol should be offered to all pregnant patients regardless of aneuploidy screening results because it has been demonstrated to identify approximately half of fetal structural malformations. Early identification of abnormalities allows focused genetic counseling, timely diagnostic testing, and subspecialist consultation. In addition, a normal ultrasound examination result offers some degree of reassurance to most patients. Use of cell-free DNA alone for aneuploidy screening while foregoing an accompanying early anatomic evaluation of the fetus will result in many anomalies that are typically detected in the first trimester not being identified until later in pregnancy, thus potentially diminishing the quality of obstetric care for pregnant individuals and possibly limiting their reproductive options, including pregnancy termination.

NIPT-PG: empowering non-invasive prenatal testing to learn from population genomics through an incremental pan-genomic approach

Non-invasive prenatal testing (NIPT) is a quite popular approach for detecting fetal genomic aneuploidies. However, due to the limitations on sequencing read length and coverage, NIPT suffers a bottleneck on further improving performance and conducting earlier detection. The errors mainly come from reference biases and population polymorphism. To break this bottleneck, we proposed NIPT-PG, which enables the NIPT algorithm to learn from population data. A pan-genome model is introduced to incorporate variant and polymorphic loci information from tested population. Subsequently, we proposed a sequence-to-graph alignment method, which considers the read mis-match rates during the mapping process, and an indexing method using hash indexing and adjacency lists to accelerate the read alignment process. Finally, by integrating multi-source aligned read and polymorphic sites across the pan-genome, NIPT-PG obtains a more accurate z-score, thereby improving the accuracy of chromosomal aneuploidy detection. We tested NIPT-PG on two simulated datasets and 745 real-world cell-free DNA sequencing data sets from pregnant women. Results demonstrate that NIPT-PG outperforms the standard z-score test. Furthermore, combining experimental and theoretical analyses, we demonstrate the probably approximately correct learnability of NIPT-PG. In summary, NIPT-PG provides a new perspective for fetal chromosomal aneuploidies detection. NIPT-PG may have broad applications in clinical testing, and its detection results can serve as a reference for false positive samples approaching the critical threshold.

The implementation and impact of non-invasive prenatal testing (NIPT) for Down's syndrome into antenatal screening programmes: A systematic review and meta-analysis

BACKGROUND

Non-invasive prenatal testing (NIPT) is a widely adopted maternal blood test that analyses foetal originating DNA to screen for foetal chromosomal conditions, including Down's syndrome (DS). The introduction of this test, which may have implications for important decisions made during pregnancy, requires continual monitoring and evaluation. This systematic review aims to assess the extent of NIPT introduction into national screening programmes for DS worldwide, its uptake, and impact on pregnancy outcomes.

METHODS AND FINDINGS

The study protocol was published in PROSPERO (CRD42022306167). We systematically searched MEDLINE, CINAHL, Scopus, and Embase for population-based studies, government guidelines, and Public Health documents from 2010 onwards. Results summarised the national policies for NIPT implementation into screening programmes geographically, along with population uptake. Meta-analyses estimated the pooled proportions of women choosing invasive prenatal diagnosis (IPD) following a high chance biochemical screening result, before and after NIPT was introduced. Additionally, we meta-analysed outcomes (termination of pregnancy and live births) amongst high chance pregnancies identified by NIPT. Results demonstrated NIPT implementation in at least 27 countries. Uptake of second line NIPT varied, from 20.4% to 93.2% (n = 6). Following NIPT implementation, the proportion of women choosing IPD after high chance biochemical screening decreased from 75% (95% CI 53%, 88%, n = 5) to 43% (95%CI 31%, 56%, n = 5), an absolute risk reduction of 38%. A pooled estimate of 69% (95% CI 52%, 82%, n = 7) of high chance pregnancies after NIPT resulted in termination, whilst 8% (95% CI 3%, 21%, n = 7) had live births of babies with DS.

CONCLUSIONS

NIPT has rapidly gained global acceptance, but population uptake is influenced by healthcare structures, historical screening practices, and cultural factors. Our findings indicate a reduction in IPD tests following NIPT implementation, but limited pre-NIPT data hinder comprehensive impact assessment. Transparent, comparable data reporting is vital for monitoring NIPT's potential consequences.

The Association between Low Fetal Fraction of Non-Invasive Prenatal Testing and Adverse Pregnancy Outcomes for Placental Compromise

(1) Background: Non-invasive prenatal testing (NIPT) is a screening test for fetal aneuploidy using cell-free fetal DNA. The fetal fragments (FF) of cell-free DNA (cfDNA) are derived from apoptotic trophoblast of the placenta. The level of fetal cfDNA is known to be influenced by gestational age, multiple pregnancies, maternal weight, and height. (2) Methods: This study is a single-center retrospective observational study which examines the relationship between the fetal fraction (FF) of cell-free DNA in non-invasive prenatal testing (NIPT) and adverse pregnancy outcomes in singleton pregnancies. A total of 1393 samples were collected between 10 weeks and 6 days, and 25 weeks and 3 days of gestation. (3) Results: Hypertensive disease of pregnancy (HDP) occurred more frequently in the low FF group than the normal FF group (5.17% vs. 1.91%, p = 0.001). Although the rates of small for gestational age (SGA) and placental abruption did not significantly differ between groups, the composite outcome was significantly higher in the low FF group (7.76% vs. 3.64%, p = 0.002). Furthermore, women who later experienced complications such as HDP or gestational diabetes mellitus (GDM) had significantly lower plasma FF levels compared to those without complications (p < 0.001). After adjustments, the low FF group exhibited a significantly higher likelihood of placental compromise (adjusted odds ratio: 1.946). (4) Conclusions: Low FF in NIPT during the first and early second trimesters is associated with adverse pregnancy outcomes, particularly HDP, suggesting its potential as a predictive marker for such outcomes.

Performance of cell-free DNA testing for common fetal trisomies in triplet pregnancies

OBJECTIVE

In singleton pregnancies, the use of cell-free DNA (cfDNA) analysis as a screening test for common fetal trisomies has spread worldwide though we still lack sufficient data for its use in triplet pregnancies. The objective of this study is to assess the performance of cfDNA testing in detecting fetal aneuploidies in triplet pregnancies as a first-tier test.

METHOD

We performed a retrospective cohort study including data from pregnant women with a triplet pregnancy who underwent cfDNA testing between May 1, 2017, and January 15, 2020. cfDNA was obtained by massive parallel sequencing (VeriSeq NIPT solution; Illumina®). The objectives of the study were to assess the diagnostic performance of cfDNA testing for trisomy 21 (T21) (primary outcome), trisomy 18 (T18) and 13 (secondary outcomes).

RESULTS

During the study period, cfDNA testing was performed in 255 women with triplet pregnancy, of which 165 (64.7%) had a neonatal outcome available. Three tests were positive for T21, one of which was confirmed by an antenatal karyotype, and the other was confirmed at birth. The third case did not undergo an invasive procedure and was not confirmed at birth (false positive). In one case, cfDNA testing was positive for T18 and was confirmed by an antenatal karyotype. There were no cases of trisomy 13 in the cohort. The no-call rate was 2.4% at first sampling. Fifty-eight (22.7%) women had embryo reduction, which in 40 (69%) of whom was performed after the cfDNA test result.

CONCLUSION

cfDNA testing could be offered as primary screening for main fetal aneuploidies in triplet pregnancies after provision of appropriate patient information.

Performance of noninvasive prenatal screening for fetal sex chromosome aneuploidies in a cohort of 116,862 pregnancies

BACKGROUND

Noninvasive prenatal screening (NIPS) has shown good performance in screening common aneuploidies. However, its performance in detecting fetal sex chromosome aneuploidies (SCAs) needs to be evaluated in a large cohort.

RESEARCH DESIGN AND METHODS

In this retrospective observation, a total of 116,862 women underwent NIPS based on DNA nanoball sequencing from 2015 to 2022. SCAs were diagnosed based on karyotyping or chromosomal microarray analysis (CMA). Among them, 2,084 singleton pregnancies received karyotyping and/or CMA. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of NIPS for fetal SCAs were evaluated.

RESULTS

The sensitivity was 97.7% (95%CI, 87.7-99.9), 87.3% (95% CI, 76.5-94.4), 96.1% (95%CI, 86.5-99.5), and 95.7% (95% CI, 78.1-99.9), the PPV was 25.8% (95%CI, 19.2-33.2), 80.9% (95%CI, 69.5-89.4), 79.0% (95%CI, 66.8-88.3), and 53.7% (95%CI, 37.4-69.3) for 45,X, 47,XXY, 47,XXX, and 47,XYY, respectively. The specificity was 94.1% (95%CI, 93.0-95.1) for 45,X, and more than 99.0% for sex chromosome trisomy (SCT). The NPV was over 99.0% for all.

CONCLUSIONS

NIPS screening for fetal SCAs has high sensitivity, specificity and NPV. The PPV of SCAs was moderate, but that of 45,X was lower than that of SCTs. Invasive prenatal diagnosis should be recommended for high-risk patients.

Technical Advances in Circulating Cell-Free DNA Detection and Analysis for Personalized Medicine in Patients' Care

Circulating cell-free DNA (cfDNA) refers to small fragments of DNA molecules released after programmed cell death and necrosis in several body fluids such as blood, saliva, urine, and cerebrospinal fluid. The discovery of cfDNA has revolutionized the field of non-invasive diagnostics in the oncologic field, in prenatal testing, and in organ transplantation. Despite the potential of cfDNA and the solid results published in the recent literature, several challenges remain, represented by a low abundance, a need for highly sensitive assays, and analytical issues. In this review, the main technical advances in cfDNA analysis are presented and discussed, with a comprehensive examination of the current available methodologies applied in each field. Considering the potential advantages of cfDNA, this biomarker is increasing its consensus among clinicians, as it allows us to monitor patients' conditions in an easy and non-invasive way, offering a more personalized care. Nevertheless, cfDNA analysis is still considered a diagnostic marker to be further validated, and very few centers are implementing its analysis in routine diagnostics. As technical improvements are enhancing the performances of cfDNA analysis, its application will transversally improve patients' quality of life.

Clinical outcomes of screen-positive genome-wide cfDNA cases for trisomy 20: results from the global expanded NIPT Consortium

Trisomy 20 has been shown to be one of the most frequent rare autosomal trisomies in patients that undergo genome-wide noninvasive prenatal testing. Here, we describe the clinical outcomes of cases that screened positive for trisomy 20 following prenatal genome-wide cell-free (cf.) DNA screening. These cases are part of a larger cohort of previously published cases. Members of the Global Expanded NIPT Consortium were invited to submit details on their cases with a single rare autosomal aneuploidy following genome-wide cfDNA screening for retrospective analysis. Clinical details including patient demographics, test indications, diagnostic testing, and obstetric pregnancy outcomes were collected. Genome-wide cfDNA screening was conducted following site-specific laboratory procedures. Cases which screened positive for trisomy 20 (n = 10) were reviewed. Clinical outcome information was available for 90% (9/10) of our screen-positive trisomy 20 cases; the case without diagnostic testing ended in a fetal demise. Of the nine cases with outcome information, one was found to have a mosaic partial duplication (duplication at 20p13), rather than a full trisomy 20. Only one case in the study cohort had placental testing; therefore, confined placental mosaicism could not be ruled out in most cases. Adverse pregnancy outcomes were seen in half of the cases, which could suggest the presence of underlying confined placental mosaicism or mosaic/full fetal trisomy 20. Based on our limited series, the likelihood of true fetal aneuploidy is low but pregnancies may be at increased risk for adverse obstetric outcomes and may benefit from additional surveillance.

Current controversies in prenatal diagnosis: Noninvasive prenatal testing should replace other screening strategies for fetal trisomies 13, 18, 21

This is a written summary of the oral debate presented at the International Society for Prenatal Diagnosis annual conference in Edinburgh in 2023. The topic under debate is whether noninvasive prenatal testing (NIPT) using cell-free fetal DNA should replace other screening strategies for the detection of fetal trisomies 13, 18, 21. There is no disagreement that NIPT is far more sensitive and has better positive predictive values for identifying trisomies 13, 18, and 21 than traditional screening approaches using biochemical markers and measurement of nuchal translucency. The major issue lies in the potential adverse consequences associated with abandoning traditional screening methods. The source of disagreement stems primarily from whether you consider the role of ultrasound in the context of screening to be strictly for nuchal translucency measurement or whether it should be combined with a fetal anatomy scan. The debate featured two experts who presented evidence in favor of each argument.

Placental, maternal, fetal, and technical origins of false-positive cell-free DNA screening results

The introduction of noninvasive prenatal testing has resulted in substantial reductions to previously accepted false-positive rates of prenatal screening. Despite this, the possibility of false-positive results remains a challenging consideration in clinical practice, particularly considering the increasing uptake of genome-wide noninvasive prenatal testing, and the subsequent increased proportion of high-risk results attributable to various biological events besides fetal aneuploidy. Confined placental mosaicism, whereby chromosome anomalies exclusively affect the placenta, is perhaps the most widely accepted cause of false-positive noninvasive prenatal testing. There remains, however, a substantial degree of ambiguity in the literature pertaining to the clinical ramifications of confined placental mosaicism and its potential association with placental insufficiency, and consequentially adverse pregnancy outcomes including fetal growth restriction. Other causes of false-positive noninvasive prenatal testing include vanishing twin syndrome, in which the cell-free DNA from a demised aneuploidy-affected twin triggers a high-risk result, technical failures, and maternal origins of abnormal cell-free DNA such as uterine fibroids or unrecognized mosaicisms. Most concerningly, maternal malignancies are also a documented cause of false-positive screening results. In this review, we compile what is currently known about the various causes of false-positive noninvasive prenatal testing.

Chromosome balanced translocation in newborn fetus founded during prenatal diagnosis: Three cases reports

RATIONALE

Because of the normal phenotype, carriers of specific chromosomal translocations are often diagnosed only after their development of associated malignancies, recurrent miscarriages, and reproductive difficulties. In this paper, we report primary balanced fetal chromosomal translocations by performing the necessary invasive prenatal diagnosis in couples with previous malformations coupled with prenatal testing suggesting a high risk for trisomy 21.

PATIENT CONCERNS

Case 1 and Case 2 couples had malformed children, and Case 3 couples had a high risk of trisomy 21 on noninvasive preconception serological testing.

DIAGNOSIS AND INTERVENTION

A balanced chromosomal translocation diagnosis was confirmed by karyotyping of fetal cells obtained by amniocentesis.

OUTCOMES

All 3 couples decided to continue their pregnancies after learning about the consequences of the chromosomal abnormalities. Approximately a year after the children were born, the staff of the Prenatal Diagnostic Center followed up with a phone call and found that the children physical development and intelligence were normal.

LESSON

This case report reports healthy chromosomal balanced translocation newborns born to couples with poor maternal history and couples with abnormalities suggested by preconception testing, and followed up with the newborns to provide some experience in prenatal diagnosis and genetic counseling for chromosomal balanced translocations.