Positive Non-invasive Prenatal Testing Result Research Articles

Performance Evaluation of Noninvasive Prenatal Testing in Screening Chromosome Disorders: A Single-Center Observational Study of 15,304 Consecutive Cases in China.

This study was to evaluate the performance of noninvasive prenatal testing (NIPT) in detecting fetal chromosome disorders in pregnant women. From October 1st, 2017, to December 31th, 2022, a total of 15,304 plasma cell free DNA-NIPT samples were collected for fetal chromosome disorders screening. The results of NIPT were validated by confirmatory invasive testing or clinical outcome follow-up. Further, NIPT performance between low-risk and high-risk groups, as well as singleton pregnancy and twin pregnancy groups was compared. Besides, analysis of 111 false-positive cases was performed. Totally, NIPT was performed on 15,086 eligible venous blood samples, of which 179 (1.19%) showed positive NIPT results and 68 were further validated to be true positive samples via confirmatory invasive testing or follow-up of clinical outcomes. For common chromosome aneuploidies, sex chromosome abnormalities (SCA) and other chromosomal aneuploidies, the detection sensitivities of NIPT were all 100%, the specificities were 99.87%, 99.70%, and 99.68% and the positive predictive values (PPVs) were 65.45%, 31.82%, and 10.91%, respectively. No statistically significant variance in detection performance was observed among 2987 high-risk and 12,099 low-risk subjects, as well as singleton and twin pregnancy subjects. The concentration of cell-free fetal DNA of 111 false-positive cases ranged from 5.5% to 33.7%, which was higher than the minimum requirement of NIPT. With stringent protocol, NIPT shows high sensitivity and specificity for detecting fetal chromosome disorders in a large-scale clinical service, helping improving overall pregnancy management.

Clinical evaluation of noninvasive prenatal testing for sex chromosome aneuploidies in 9,176 Korean pregnant women: a single-center retrospective study

BackgroundTo evaluate the clinical significance of noninvasive prenatal testing (NIPT) for detecting fetal sex chromosome aneuploidies (SCAs) in Korean pregnant women.MethodsWe retrospectively analyzed NIPT data from 9,176 women with singleton pregnancies referred to the CHA Biotech genome diagnostics center. Cell-free fetal DNA (cffDNA) was extracted from maternal peripheral blood, and high-throughput massively parallel sequencing was conducted. Subsequently, the positive NIPT results for SCA were validated via karyotype and chromosomal microarray analyses.ResultsOverall, 46 cases were SCA positive after NIPT, including 20, 12, 8, and 6 for Turner, triple X, Klinefelter, and Jacob syndromes, respectively. Among 37 women with invasive prenatal diagnosis, 19 had true positive NIPT results. The overall positive predictive value (PPV) of NIPT for detecting SCAs was 51.35%. The PPV was 18.75% for Turner, 88.89% for triple X, 71.43% for Klinefelter, and 60.00% for Jacob’s syndromes. NIPT accuracy for detecting sex chromosome trisomies was higher than that for sex chromosome monosomy (P = 0.002). No significant correlation was observed between fetal SCA incidence and maternal age (P = 0.914), except for the borderline significance of Jacob’s syndrome (P = 0.048). No significant differences were observed when comparing NIPT and karyotyping validation for fetal SCA according to pregnancy characteristics.ConclusionOur data suggest that NIPT can reliably screen for SCAs, and it performed better in predicting sex chromosome trisomies compared with monosomy X. No correlation was observed between maternal age and fetal SCA incidence, and no association was observed between different pregnancy characteristics. The accuracy of these findings requires improvements; however, our study provides an important reference for clinical genetic counseling and further management. Larger scale studies, considering confounding factors, are required for accurate evaluation.

Prenatal diagnosis after high chance non-invasive prenatal testing for trisomies 21, 18 and 13, chorionic villus sampling or amniocentesis? - Experience at a district general hospital in the United Kingdom.

The non-invasive prenatal testing (NIPT) analyses cell-free DNA (cfDNA) derived from the placental tissue in the maternal circulation. Though highly sensitive and specific, a major limitation is in cases of confined placental mosaicism (CPM). Whether to perform chorionic villus sampling (CVS) or amniocentesis to confirm a positive NIPT result is controversial. One major drawback of CVS is that cytogenetic diagnosis may not always reflect the true chromosomal make-up of the fetus. This work, therefore, proposes the use of amniocentesis in the presence of normal ultrasound findings, and the option of either CVS or amniocentesis when there are abnormal USS findings.

Non-invasive prenatal testing for everybody or contingent screening?

To compare the advantages and disadvantages of two main implementation strategies for non-invasive prenatal testing (NIPT) for the detection of trisomies 21, 13 and 18 in public healthcare settings. These concern NIPT as a first-tier screening test for all pregnant women, or NIPT contingent on an increased risk first-trimester combined test (FCT) result. Comparison based on (un)published data and literature. Despite the lower prevalence of trisomies in the low-risk population, data show that the positive predictive value (PPV) and detection-miscarriage ratio of first-tier NIPT are comparable to NIPT used as contingency test. Advantages of NIPT as a first-tier test compared to FCT with contingent NIPT are that there is no time-window for testing, sensitivity is higher, fewer women need follow-up testing (PPV of NIPT is higher than PPV of FCT), less anxiety for pregnant women and partners. When given the choice, pregnant women prefer first-tier NIPT. Although contingency testing still seems to be the cheaper option, the differences in costs are becoming increasingly smaller and might soon disappear. We argue that NIPT should preferably be offered as a first-tier test for the detection of fetal aneuploidies for all pregnant women, provided that women are supported to make informed decisions. This article is protected by copyright. All rights reserved.

Pitfalls of prenatal diagnosis associated with mosaicism

Key content Fetal placental mosaicism, of which confined placental mosaicism is a subtype, occurs in 2–3% of pregnancies. Confined placental mosaicism may lead to a false positive result on non‐invasive prenatal testing (NIPT) for common aneuploidies. The risk of mosaicism in a chorionic villus sample (CVS) following a positive NIPT result is 2, 4, 22 and 59% for trisomy 21, 18, 13 and 45, X respectively. Following a positive NIPT result in the absence of a significant fetal structural anomaly (FSA), care is required in selecting the optimal diagnostic invasive test. Discussion of the limitations and implications is essential and referral to clinical genetics may be warranted. Learning objectives To understand the embryological causes for and types of fetal placental mosaicism. To appreciate underlying principles in NIPT and genomic testing strategies in relation to mosaicism. To follow suggested clinical management principles in relation to prenatal test counselling. Ethical issues Clinicians face a dilemma following a high‐risk NIPT result in the setting of normal ultrasound. Awaiting long‐term culture, as opposed to short‐term culture on CVS, or amniocentesis delays potential termination of pregnancy. Sex chromosome abnormalities on NIPT without an identifiable FSA cannot be interpreted reliably. Hence, NIPT should not be offered for sex chromosome aneuploidy.

Whole genome non-invasive prenatal testing in prenatal screening algorithm: clinical experience from 12,700 pregnancies

BackgroundA fast adoption of a non–invasive prenatal testing (NIPT) in clinical practice is a global tendency last years. Firstly, in Russia according a new regulation it was possible to perform a widescale testing of pregnant women in chromosomal abnormality risk. The aim of the study—to assess efficiency of using NIPT as a second-line first trimester screening test in Moscow.MethodsBased on the first trimester combined prenatal screening results 12,700 pregnant women were classified as a high-risk (cut-off ≥ 1:100) and an intermediate-risk (cut-off 1:101 – 1:2500) groups followed by whole genome NIPT. Women from high-risk group and those who had positive NIPT results from intermediate-risk group were considered for invasive prenatal diagnostic.Results258 (2.0%) samples with positive NIPT results were detected including 126 cases of trisomy 21 (T21), 40 cases of T18, 12 cases of T13, 41 cases of sex chromosome aneuploidies (SCAs) and 39 cases of rare autosomal aneuploidies (RAAs) and significant copy number variations (CNVs). Statistically significant associations (p < 0.05) were revealed for fetal fraction (FF) and both for some patient’s (body mass index and weight) and fetus’s (sex and high risk of aneuploidies) characteristics. NIPT showed as a high sensitivity as specificity for common trisomies and SCAs with an overall false positive rate 0.3%.ConclusionsNIPT demonstrated high sensitivity and specificity. As a second-line screening test it has shown a high efficiency in detecting fetus chromosomal anomalies as well as it could potentially lower the number of invasive procedures in pregnant women.

Pregnancies with positive non-invasive prenatal testing result for sex chromosome abnormalities in a tertiary hospital in Hong Kong

Pregnancies with positive non-invasive prenatal testing result for sex chromosome abnormalities in a tertiary hospital in Hong Kong

Genetic Counseling and Management: The First Study to Report NIPT Findings in a Romanian Population

Background and Objectives: Non-invasive prenatal testing (NIPT) has been confirmed as the most accurate screening test for trisomies 21, 18, 13, sex chromosomes aneuploidies and several microdeletions. This study aimed to assess the accuracy of cell free DNA testing based on low-level whole-genome sequencing to screen for these chromosomal abnormalities and to evaluate the clinical performance of NIPT. Materials and Methods: 380 consecutive cases from a single genetic center, from Western Romania were included in this retrospective study. Cell-free nucleic acid extraction from maternal blood, DNA sequencing and analysis of sequenced regions were performed by BGI Hong Kong and Invitae USA to determine the risk of specific fetal chromosomal abnormalities. In high-risk cases the results were checked by direct analysis of fetal cells obtained by invasive methods: 6 chorionic villus sampling and 10 amniocenteses followed by combinations of QF-PCR, karyotyping and aCGH. Results: NIPT results indicated low risk in 95.76% of cases and high risk in 4.23%. Seven aneuploidies and one microdeletion were confirmed, the other results were found to be a false-positive. A gestational age of up to 22 weeks had no influence on fetal fraction. There were no significant differences in fetal fraction across the high and low risk groups. Conclusions: This is the first study in Romania to report the NIPT results. The confirmation rate was higher for autosomal aneuploidies compared to sex chromosome aneuploidies and microdeletions. All cases at risk for trisomy 21 were confirmed. Only one large fetal microdeletion detected by NIPT has been confirmed. False positive NIPT results, not confirmed by invasive methods, led to the decision to continue the pregnancy. The main limitation of the study is the small number of patients included. NIPT can be used as a screening method for all pregnancies, but in high-risk cases, an invasive confirmation test was performed.

The role of first-trimester ultrasound screening for women with positive noninvasive prenatal testing results.

This study aimed to assess the utility of ultrasound screening for pregnancies with positive noninvasive prenatal testing results for trisomy 21, trisomy 18, and trisomy 13. We performed a retrospective analysis of positive noninvasive prenatal testing results and first-trimester ultrasound screening at our department between 2013 and 2019. Invasive genetic testing was performed if the patient had positive noninvasive prenatal testing results. Fetal ultrasound and cytogenetic data were collected. Noninvasive prenatal testing was performed in the women for advanced maternal age, nuchal translucency thickness, or history of abnormality in the previous child or relative. Forty-one pregnant women had positive noninvasive prenatal testing results for trisomy 21, trisomy 18, and trisomy 13. Twenty-three women had positive results for trisomy 21, 13 had positive results for trisomy 18, and 5 had positive results for trisomy 13 at 11 to 14 weeks of gestation. The positive predictive value of noninvasive prenatal testing was 100% for trisomy 21, 84.6% for trisomy 18, and 100% for trisomy 13. The positive predictive value of positive noninvasive prenatal testing results and fetal morphological abnormalities was 100% for trisomy 21, trisomy 18, and trisomy 13. Combining an ultrasound examination with noninvasive prenatal testing resulted in a higher positive predictive value for trisomy 18. Normal ultrasound examination results can help alleviate stress caused by false-positive noninvasive prenatal testing results. In contrast, the positive predictive value and negative predictive value for trisomy 21 were not altered by adding an ultrasound examination to noninvasive prenatal testing.

Trends of fetal chromosome analysis by amniocentesis before and after beginning of noninvasive prenatal testing: A single-center experience in Japan.

This study is to investigate the role of amniocentesis for prenatal diagnosis before and after the beginning of noninvasive prenatal testing (NIPT) in Japan. We performed a retrospective analysis of genetic amniocentesis at mid-trimester (15-20 gestational weeks) for fetal karyotype analysis at Nagoya City University between April 2006 and March 2020. The indications, test results, and the detection rate of fetal abnormal karyotype were compared before (phase 1, P1) and after (phase 2, P2) beginning of NIPT at April 2013. A total of 2458 (P1: 1132, P2: 1326) amniocentesis were enrolled in this study. The most frequent indication was advanced maternal age in both phases (P1: 78.2% %, P2: 81.1%). In P2, 110 patients (8.3%) received amniocentesis after positive or nonreportable NIPT results. Other indications were fetal abnormal findings by ultrasounds (P1: 15.4%, P2: 17.7%), abnormal maternal serum screening results (P1: 8.0%, P2: 10%), previous child with fetal chromosome aberration (P1: 6.5%, P2: 3.5%), and translocation of either partner (P1:1.5%, P2: 2.1%). The detection rate for fetal chromosomal aberrations including all indications was significantly increased in P2 (15.9%, 95% CI 14.0-18.0) as compared to P1 (9.0%, 7.4-10.8). However, if the indication was only advanced maternal age, the positive detection rate kept low in both phases (P1: 5.2%, 3.7-7.1, P2: 4.2%, 2.9-5.9). Since the initiation of NIPT, the detection rate of fetal chromosomal abnormalities was higher in this study, suggesting that amniocentesis cannot be strongly recommended for advanced maternal age alone.

Performance of non-invasive prenatal testing for foetal chromosomal abnormalities in 1048 twin pregnancies

ObjectiveTo investigate the clinical value of non-invasive prenatal testing (NIPT) to screen for chromosomal abnormalities in twin pregnancies and to provide further data on NIPT manifestations in twin pregnancies.Materials and methodsIn a 4-year period, 1048 women with twin pregnancies were voluntarily prospectively tested by NIPT to screen for chromosomal abnormalities by sequencing cell-free foetal DNA (cffDNA) in maternal plasma. Positive NIPT results were confirmed by karyotyping, while negative results were followed up 42 days after delivery.ResultsThirteen women had positive NIPT results as follows: 2 cases of trisomy 21 (T21), 1 of trisomy 18 (T18), 7 of sex chromosome aneuploidy (SCA), 1 of microdeletion, and 2 of microduplication. Of these 13 cases, 2 were true-positive cases confirmed by foetal karyotype analysis, namely, 1 case of T21 and 1 of microdeletion. Furthermore, the remaining 11 high-risk pregnant women were confirmed as false positive by foetal karyotyping. Thus, the combined positive predictive value (PPV) of NIPT screening for chromosomal abnormalities in twin pregnancies was 15.4% (2/13). There were no false-negative case via our follow-up results.ConclusionSafe and rapid NIPT has a certain clinical application value; however, the PPV is limited, and the screening efficiency is not stable. Careful use should be made in the screening of chromosomal abnormalities in twin pregnancies.

An assessment of the analytical performance of non-invasive prenatal testing (NIPT) in detecting sex chromosome aneuploidies: 34,717-patient sample in a single prenatal diagnosis Centre in China.

The present study aimed to evaluate the efficacy of a non-invasive prenatal test (NIPT) in the detection of the sex chromosome aneuploidies (SCAs) at our prenatal diagnosis centre. Among a cohort of 34,717 pregnancies, maternal plasma samples from our prenatal diagnosis centre were subject to analysis of SCAs using NIPT detection. Pregnant women with NIPT positive results of SCAs were recommended to undergo an invasive prenatal diagnosis (i.e. karyotyping and fluorescence in situ hybridization) to validate the prediction value of NIPT. From 34,717 clinical pregnancies, 229 (0.66%) pregnancies were identified with SCAs. Of these, 78 (34.1%) cases were positive for 45,X and 151 (65.9%) cases comprised a sex chromosome trisomy. Of the 229 positive NIPT results, 193 (84.3%) cases had accepted an invasive diagnosis involving karyotyping analysis of the amniotic fluid, which confirmed 67 cases (34.7%) as true positive, as well as 126 cases (65.3%) as false positive. The positive predictive values were 23.07%, 50%, 36% and 27.27% respectively. The remaining 36 (15.7%) cases declined a prenatal diagnosis. The termination rates of 45,X, 47,XXY, 47,XXX and 47,XYY were 20.5%,46%,12.9% and 11.5% respectively. NIPT demonstrated a lower accuracy in predicting monosomy X than sex chromosome trisomies. After invasive testing, the fetal chromosome with 45,X and 47,XXY were terminated more often than those with 47,XXX, 47,XYY. Because NIPT is a screening test, false positive/negative cases exist, and pre- and post-test counselling is essential for informing patients about the benefits and limitations of the test. Confirmatory testing of abnormal results is recommended prenatally or after birth, and the importance of confirmatory testing and benefits of early diagnosis should be addressed.

Performance and Diagnostic Value of Genome-Wide Noninvasive Prenatal Testing in Multiple Gestations

To evaluate the accuracy and diagnostic value of genome-wide noninvasive prenatal testing (NIPT) for the detection of fetal aneuploidies in multiple gestations, with a focus on dichorionic-diamniotic twin pregnancies. We performed a retrospective cohort study including data from pregnant women with a twin or higher-order gestation who underwent genome-wide NIPT at one of the eight Belgian genetic centers between November 1, 2013, and March 1, 2020. Chorionicity and amnionicity were determined by ultrasonography. Follow-up invasive testing was carried out in the event of positive NIPT results. Sensitivity and specificity were calculated for the detection of trisomy 21, 18, and 13 in the dichorionic-diamniotic twin cohort. Unique NIPT analyses were performed for 4,150 pregnant women with a multiple gestation and an additional 767 with vanishing gestations. The failure rate in multiple gestations excluding vanishing gestations ranged from 0% to 11.7% among the different genetic centers. Overall, the failure rate was 4.8%, which could be reduced to 1.2% after single resampling. There were no common fetal trisomies detected among the 86 monochorionic-monoamniotic and 25 triplet cases. Two monochorionic-diamniotic twins had an NIPT result indicative of a trisomy 21, which was confirmed in both fetuses. Among 2,716 dichorionic-diamniotic twin gestations, a sensitivity of 100% (95% CI 74.12-100%) and a specificity of 100% (95% CI 99.86-100%) was reached for trisomy 21 (n=12). For trisomy 18 (n=3), the respective values were 75% (95% CI 30.06-95.44%) sensitivity and 100% (95% CI 99.86-100%) specificity, and for trisomy 13 (n=2), 100% (95% CI 20.65-100%) sensitivity and 99.96% (95% CI 99.79-99.99%) specificity. In the vanishing gestation group, 28 NIPT results were positive for trisomy 21, 18, or 13, with only five confirmed trisomies. Genome-wide NIPT performed accurately for detection of aneuploidy in dichorionic-diamniotic twin gestations.

Next-generation sequencing: a follow-up of 36,913 singleton pregnancies with noninvasive prenatal testing in central China

PurposeTo evaluate the noninvasive prenatal testing (NIPT) results of 36,913 cases in Jiangxi province of central China and explore its application value in prenatal screening and diagnosis.MethodsThis retrospective analysis included 36,913 singleton pregnant women who underwent NIPT because of moderate-/high-risk pregnancy or voluntary requirements between January 2017 and December 2019 in our hospital. Chromosomal abnormalities such as trisomies 21, 18, and 13 (T21, T18, T13) and sex chromosome aneuploidies (SCAs) were judged by standard Z-score analysis. Positive NIPT results were confirmed by amniocentesis and karyotyping. Pregnancy outcomes were followed up via telephone interview.ResultsA total of 1.01% (371/36,913) positive cases were detected by NIPT, comprising 137, 46, 31, and 157 cases of T21, T18, T13, and SCAs, respectively. A total of 116 of T21, 27 of T18, 13 of T13, and 51 of SCAs were confirmed to be true positive; all normal cases that had been followed up were verified to be true negative. The NIPT sensitivity in T21, T18, T13, and SCAs was 100.00% individually, whereas the specificity was 99.94% (36,488/36,509), 99.95% (36,579/36,598), 99.95% (36,594/36,612), and 99.72% (36,472/36,574), respectively. Furthermore, the negative predictive values of T21, T18, T13, and SCAs were all 100%, while the positive predictive values were 84.67%, 58.70%, 41.94%, and 33.33%, respectively.ConclusionNIPT is highly sensitive and has a low false positive rate in testing clinically significant fetal aneuploidies of general reproductive women. However, this technique cannot substitute for amniocentesis and karyotyping, and detailed genetic counseling is also essential for the high-risk group of NIPT.

Performance of non-invasive prenatal screening for sex chromosome aneuploidies and parental decision-making.

Performance of non-invasive prenatal screening for sex chromosome aneuploidies and parental decision-making.

The role of ultrasound in women with a positive NIPT result for trisomy 18 and 13

ObjectiveThe aim of this study was to evaluate the usefulness of ultrasound in pregnancies with a positive non-invasive prenatal testing (NIPT) result for trisomy 18/13. Materials and methodsDuring a four-year period, the pregnant women who were referred for invasive genetic testing because of positive NIPT results for trisomy 18/13 were included in this study. An in-depth ultrasound was done for these patients before invasive procedures. The data of fetal ultrasound and cytogenetic results were collected. ResultsThere were 81 patients with a positive NIPT result for trisomy 18/13, including 39 (30 positive for trisomy 18; 9 positive for trisomy 13) within 12–14 weeks of gestation, and 42 (31 positive for trisomy 18; 11 positive for trisomy 13) within 15–22 weeks. The PPV of NIPT was 60.7% for trisomy 18, and 30% for trisomy 13, respectively. When adding ultrasound to NIPT, the new PPV for trisomy 18 was 100%, and the negative predictive value (NPV) was 92.3%, with a NPV of 85.7% in the first trimester and a NPV of 100% in the second trimester, respectively. The new PPV and NPV for trisomy 13 were 100% and 100%, respectively. ConclusionBy adding ultrasound to the NIPT, we achieved much higher PPVs and NPVs for trisomy 18/13. A normal scan can help to alleviate stress in parents caused by false positive NIPT results.

Noninvasive Prenatal Testing Using Next Generation Sequencing: Pilot Experience of the D.O. Ott Research Institute of Obstetrics, Gynecology and Reproductology

In recent years, noninvasive prenatal testing (NIPT) for fetal chromosomal abnormalities has come into wide use. NIPT allows detection of fetal chromosomal abnormalities without invasive sampling of fetal material: by analyzing cell-free fetal DNA in maternal blood. Here, we report on the pilot results of using NIPT at the D.O. Ott Research Institute of Obstetrics, Gynecology and Reproductology (St. Petersburg, Russia). The results obtained in 149 blood samples from pregnant women proved the clinical value of NIPT for detection of fetal trisomies 21, 18, and 13. Aneuploidy was detected in 20 out of 149 samples. Among these 20 aneuploid cases, trisomy 21 amounted to 60%, trisomy 18 – to 25%, and trisomy 13 to 5% of cases. In one sample, double aneuploidy involving chromosomes 13 and 21 was detected, and in one case, trisomy X was identified. In 100% of cases, aneuploidies were confirmed by prenatal karyotyping advocating for the absence of false positive NIPT results. The observed high specificity was consistent with the declared test specificity level of >99.9%. The sensitivity of the method was 100%. To summarize, NIPT is a new reliable technique that will probably soon replace the conventional first trimester combined screening. The only disadvantages of implementing NIPT in Russia are its relatively high cost and the lack of coverage by insurance companies. NGS-based NIPT is suitable for clinical practice and will be widely deployed due to a further cost decrease.

The role of ultrasound in the choice between chorionic villus sampling and amniocentesis for patients with a positive NIPT result for trisomy 18/13.

What's already known about this topic? Positive predict value (PPV) is vitally important because it indicates the probability that a positive test result represents a true fetal abnormality. PPV of noninvasive prenatal testing (NIPT) is lower for trisomy 18/13 compared with trisomy 21. What does this study add? In our study cohort of women with a high‐risk noninvasive prenatal testing (NIPT) result and normal nuchal translucency measurement, &gt;90% (32/35) of cases with true fetal trisomy 18/13 had a fetal abnormality on ultrasound, compared with none of the fetuses with confined placental mosaicism and normal amniocentesis result. Detailed sonographic examination of the fetus following a high‐risk NIPT result for trisomy 13/18 is an important component of clinical management and may influence the choice of confirmatory prenatal diagnostic procedure.

Clinical features and pregnancy outcomes of women with abnormal cell-free fetal DNA test results.

This study was performed to examine the factors affecting attitudes regarding prenatal diagnosis and clinical treatment by analyzing the clinical data of women with positive noninvasive prenatal testing (NIPT) results. We collected clinical data for women with positive NIPT results. The women received prenatal genetic consultation. The women with true positive results received prenatal genetic counseling again, and decided whether to continue or terminate their pregnancy. A total of 228 women received positive NIPT results. The prenatal diagnosis was accepted in 174 cases (76.3%), and 124 women were confirmed to have true positive NIPT results. The positive predictive values (PPV) of T21/T18/T13 and fetal sex chromosome aneuploidy were 88.4% and 42.9%, respectively. All (99/99, 100%) of the women with T21/T18/T13 terminated their pregnancies, while 25.0% (6/24) of women with fetal SCA continued their pregnancies. An NIPT result of Chr(9) microduplication was obtained in one woman, which was confirmed by chromosomal microarray analysis (CMA). NIPT exhibited good detection accuracy for T21/T18/T13, and also contributed to identifying fetal SCA and substructural chromosomal abnormalities. With a positive NIPT result, the attitudes of pregnant women regarding prenatal diagnosis and clinical treatment are related to the severity of disease, cognitive ability, and the level of prenatal genetic counseling.

Non-invasive prenatal testing for detection of trisomy 13, 18, 21 and sex chromosome aneuploidies in 8594 cases.

Cell-free fetal DNA has been widely used in prenatal genetic testing during recent years. We explored the feasibility of non-invasive prenatal testing (NIPT) for analysis of common fetal aneuploidies among pregnancies in northwest China. A total of 8594 maternal blood samples were collected from October 2014 to December 2017 in the Department of Obstetrics and Gynecology at the First Affiliated Hospital of the Air Force Medical University. Cases with positive screening results by NIPT detection were validated using karyotype analysis. Of 8594 clinical pregnancies, 88 had positive NIPT results and 78 of 88 (88.6%) positive NIPT results were shown to be false-positive by amniotic fluid puncture and chromosome karyotyping analysis. There were 44 cases (49.44%) with trisomy 21, 18, and 13 syndromes (30 cases of trisomy 21, 9 cases of trisomy 18, and 5 cases of trisomy 13). There were 44 cases (50.56%) with sex chromosome abnormalities, including 11 cases with Turner syndrome (45, X), 17 cases with Triple X syndrome (47, XXX), 2 cases with Klinefelter syndrome (47, XXY), and 14 cases with 47, XYY syndrome (47, XYY). The accuracy, specificity, high efficiency, and acceptance of NIPT can effectively avoid birth defects and improve the quality of the birth population. We should deepen mining and analysis of the clinical data and explore ways to use NIPT. It is recommended that the NIPT guidelines be extended to low-risk patients to further explore the impact of a significant increase in screening.