Clinical utility and cost of non-invasive prenatal testing with cfDNA analysis in high-risk women based on a US population

Abstract

Objective: Evaluate the clinical and economic consequences of fetal trisomy 21 (T21) screening with non-invasive prenatal testing (NIPT) in high-risk pregnant women.

Methods: Using a decision-analytic model, we estimated the number of T21 cases detected, the number of invasive procedures performed, corresponding euploid fetal losses and total costs for three screening strategies: first trimester combined screening (FTS), integrated screening (INT) or NIPT, whereby NIPT was performed in high-risk patients (women 35 years or older or women with a positive conventional screening test). Modeling was based on a 4 million pregnant women cohort in the US.

Results: NIPT, at a base case price of $795, was more clinically effective and less costly (dominant) over both FTS and INT. NIPT detected 4823 T21 cases based on 5330 invasive procedures. FTS detected 3364 T21 cases based on 108?364 procedures and INT detected 3760 cases based on 108?760 procedures. NIPT detected 28% and 43% more T21 cases compared to INT and FTS, respectively, while reducing invasive procedures by >95% and reducing euploid fetal losses by >99%. Total costs were $3786M with FTS, $3919M with INT and $3403M with NIPT.

Conclusions: NIPT leads to improved T21 detection and reduction in euploid fetal loss at lower total healthcare expenditures.     

Cell-Free DNA–Based Non-invasive Prenatal Screening for Common Aneuploidies in a Canadian Province: A Cost-Effectiveness Analysis

Objective

Yearly, 450?000 pregnant Canadians are eligible for voluntary prenatal screening for trisomy 21. Different screening strategies select approximately 4% of women for invasive fetal chromosome testing. Non-invasive prenatal testing (NIPT) using maternal blood cell-free DNA could reduce those invasive procedures but is expensive. This study evaluated the cost-effectiveness of NIPT strategies compared with conventional strategies.

Perinatal outcomes of prenatal cases testing positive for trisomy 9 by noninvasive prenatal testing

ObjectivesTo evaluate the performance of non-invasive prenatal testing (NIPT) for the detection of fetal trisomy 9 in prenatal screening and to investigate the prenatal appearances and genetic counseling of trisomy 9 fetuses.Materials and methodsThe ultrasonography information, laboratory detection and pregnancy outcome of 16 cases of single pregnancy with trisomy 9 identified by NIPT who received amniocentesis in our prenatal diagnosis center from January 2018 to December 2020 were retrospectively analyzed.ResultsAmong the 16 cases, 2 cases of trisomy 9, 3 cases of trisomy 9 mosaicism, 2 cases reporting of regions of homozygosity and 9 cases of false positive were diagnosed. Among the true positive cases, 4 cases showed abnormal ultrasonic finding: 3 cases terminated pregnancy and 1 case was lost to follow-up. Another 1 case was in utero fetal demise in the second trimester without structural abnormality, and 2 cases were normal live birth without developmental abnormalities. In the 9 cases with normal kayrotyping, 1 case had termination of pregnancy and 1 case with mental retardation and poor cognitive ability, other 7 had good pregnancy outcomes.ConclusionOur results may be helpful for the selection of prenatal diagnostic strategies and genetic counseling for pregnant women with trisomy 9 revealed by NIPT.     

Fetal aneuploidy screening with cell-free DNA in late gestation

Objective: The aim of this study was to evaluate clinical use of NIPT at gestational ages of 23 weeks and above.

Methods: A cohort of 5579 clinical patients with singleton gestations of 23 weeks or greater submitting a blood sample for NIPT in an 18-month period were selected for this study. Clinical outcomes were requested for samples with NIPT results indicating fetal aneuploidy and compared with NIPT findings to confirm concordance or discordance.

Results: A review of clinical indications revealed that a significantly (p?Conclusions: NIPT is a highly accurate prenatal screening option for women after 23 weeks of gestation. Women who presented for NIPT in the latter stages of pregnancy more frequently specified clinical indications of abnormal ultrasound findings than women who entered screening earlier in pregnancy.     

Noninvasive prenatal testing (NIPT) detects variant of Turner syndrome not detectable by fluorescent in situ hybridization

Abstract

Introduction: Noninvasive prenatal testing (NIPT) is a reliable screening method for fetal aneuploidy detection of trisomy 18, 13, 21 along with few sex chromosome abnormalities monosomy X, XXX, XXY (Klinefelter), XYY (Jacob) syndromes and certain microdeletions which include cri-du-chat, DiGeorge, 1p36, Angelman, and Prader-Willi syndromes in comparison to the available screening methods. Prenatal screening of Turners syndrome is possible by ultrasound in certain conditions only. Recently benefits of early detection and treatment of Turners syndrome has been emphasized, enforcing on accurate and early screening prenatally.

Case details: The current case emphasizes on the reliability of NIPT testing which comes with an advantage of early screening. A 24-year-old primi gravida was referred for NIPT as she tested for high risk on biochemical screening. The Panorama? NIPT results showed low risk for trisomies, 21, 18, and 13 but high risk of monosomy X and was advised confirmatory amniocentesis. The fluorescence in situ hybridization (FISH) report revealed no numerical abnormality detected for any of the five chromosomes tested. On receiving this discordant report, the sample was rerun for NIPT, to rule out any laboratory-related issues. The result obtained on a rerun was consistent with the first report and showed monosomy X again. The karyotype report was available three weeks later and a rare variant of Turners syndrome was identified.

Discussion: Panorama? NIPT considers single nucleotide polymorphisms spread across the chromosomes for analysis, different variants of aneuploidy can be picked up in comparison to FISH, similar to the current case wherein it could not as it was a centromeric probe. Reported first case of X chromosome variant detected by NIPT confirmed by karyotyping, missed by FISH.     

Non-invasive prenatal testing: impact on invasive prenatal diagnosis at a mainland Chinese tertiary medical center

Objective: We describe the changes over a 4-year period in the number of diagnostic testing after the introduction of non-invasive prenatal testing (NIPT).

Methods: The rate of NIPT as an indication in women who received amniocentesis, and the number of amniocentesis required for detection of one case with major aneuploidy were compared between a 1-year baseline period before the introduction of NIPT, and the 3 years following NIPT introduction.

Results: A total of 7536 amniocentesis procedures were performed over the 4-year study period. During the baseline period of the year 2011, the number of invasive testing required for detection of one common trisomy was 57. During the first 2 years that NIPT was offered, NIPT averaged 1.7 percent of the total indications for amniocentesis, and the required number of invasive testing decreased to 30. With the increase of the percentage of NIPT during the 3rd year, the required number of invasive testing further decreased to 26.

Conclusion: After the clinical introduction of NIPT, invasive prenatal diagnostic testing had not decreased at a Chinese prenatal diagnostic unit, but a remarkably improved detection rate of major aneuploidies in diagnostic procedures was observed.     

Questioning the costs and benefits of non-invasive prenatal testing

Abstract

Prenatal testing for Down syndrome through the use of non-invasive prenatal testing (NIPT) has been increasingly implemented in clinical practice and a recent cost analysis suggests that NIPT is cost effective when compared to other screening modalities in high risk populations. However, this anaylsis makes many assumptions regarding uptake of testing and pregnancy termination, which cannot be applied to all populations in the United States. Additionally, this cost analysis, which hinges on fewer Down syndrome births, does not align with the goals of prenatal testing to support autonomous and value consistent decisions. NIPT is an expensive new technology and more careful analysis is needed to determine the impact of NIPT on outcomes and overall healthcare costs.     

Canadian women’s attitudes toward noninvasive prenatal testing of fetal DNA in maternal plasma*

Objective: To determine the perceptions and attitudes of Canadian women to Noninvasive Prenatal Testing of fetal DNA.

Study design: A designed questionnaire was administered to women attending the outpatient antenatal clinic at a tertiary urban hospital. Attitudes to current and new prenatal screening modalities were assessed using a five-point Likert scale. Bowker’s test of symmetry was used to compare individual responses regarding the two screening modalities. Changes in women’s responses pre- and post-delivery were also compared.

Results: One hundred and twenty-nine women were enrolled in this study. 88% of women state that they would perform prenatal screening via fetal DNA in the maternal plasma if available. When compared to conventional screening, significantly less women believe that the NIPT should be available upon request for non-medical traits (36.4% versus 60.4%, p?<?0.001). When compared to their answer before delivery, more women agreed that screening with fetal DNA in maternal plasma could be used in a negative way to select for desired non-medical traits such as gender.

Conclusions: The use of fetal DNA in the maternal plasma is widely accepted in our Canadian population as a future method of noninvasive prenatal screening despite recognition of certain ethical concerns. This information can be used when implementing new genetic screening programs.     

无创DNA检测在诊断高龄孕妇胎儿非整倍体中的应用

目的:探讨高龄妊娠胎儿染色体异常的风险以及无创DNA产前检测(NIPT)在诊断高龄孕妇胎儿非整倍体染色体病中的应用价值。方法:选择≥35岁的高龄孕妇2714例,按年龄分为35~39岁,≥40岁两组,采用NIPT高通量测序检测孕妇血浆游离DNA,并对检测结果提示21-三体、18-三体、13-三体及性染色体高风险者行羊膜腔穿刺术及胎儿染色体核型分析,对检测结果阴性者通过电话随访进行验证。计算NIPT检测的敏感度、特异度、阳性预测值、阴性预测值及Youden指数。结果:2714例高龄孕妇NIPT检测结果提示胎儿非整倍体染色体异常高风险47例,6例高风险孕妇拒绝侵入性产前诊断,余41例高风险孕妇行羊膜腔穿刺术及羊水细胞染色体核型分析,结果显示21-三体19例,18-三体1例,13-三体2例,性染色体异常7例。与现有的金标准羊膜腔穿刺术核型分析相比较,NIPT对高龄孕妇除外性染色体异常的胎儿非整倍体染色体异常检出敏感度为100.00%,特异度为99.93%,阳性预测值为90.91%,阴性预测值为100.00%,Youden指数为0.99。进一步通过年龄分组发现,40岁及以上年龄组异常率显著高于35~39岁年龄组(P=0.011)。结论:高龄孕妇可通过NIPT快速、安全地筛查出胎儿非整倍体染色体异常,减少侵入性产前检测比例,降低胎儿出生缺陷率。     

Noninvasive Prenatal Testing for Trisomies 21, 18, and 13, Sex Chromosome Aneuploidies,and Microdeletions in Average-Risk Pregnancies: A Cost-Effectiveness Analysis

ObjectiveThe cost effectiveness of noninvasive prenatal testing (NIPT) has been established for high-risk pregnancies but remains unclear for pregnancies at other risk levels. The aim was to assess the cost effectiveness of NIPT in average-risk pregnancies from the perspective of a provincial public payer in Canada.MethodsA model was developed to compare traditional prenatal screening (TPS), NIPT as a second-tier test (performed only after a positive TPS result), and NIPT as a first-tier test (performed instead of TPS) for trisomies 21, 18, and 13; sex chromosome aneuploidies; and microdeletions in a hypothetical annual population cohort of average-risk pregnancies (142 000 to 148,000) in Ontario, Canada. A probabilistic analysis was conducted with 5000 repetitions.ResultsCompared with TPS, NIPT as a second-tier test detected more affected fetuses with trisomies 21, 18, and 13 (188 vs. 158), substantially reduced the number of diagnostic tests (i.e., chorionic villus sampling and amniocentesis) performed (660 vs. 3107), and reduced the cost of prenatal screening ($26.7 million vs. $27.6 million) annually. Compared with second-tier NIPT, first-tier NIPT detected an additional 80 cases of trisomies 21, 18, and 13 at an additional cost of $33 million. The incremental cost per additional affected fetus detected was $412 411. Extending first-tier NIPT to include testing for sex chromosome aneuploidies and 22q11.2 deletion would increase the total screening cost.ConclusionsNIPT as a second-tier test is cost-saving compared with TPS alone. Compared with second-tier NIPT, first-tier NIPT detects more cases of chromosomal anomalies but at a substantially higher cost.     

Survey of US obstetrician opinions regarding NIPT use in general practice: implementation and barriers

Objective: To evaluate the knowledge and opinions of US obstetric providers who use noninvasive prenatal testing (NIPT) to understand current utilization and guide future best practices.

Methods: A questionnaire was designed to assess the level of knowledge and attitudes of OBGYNs toward screening options for aneuploidy, with a focus on NIPT. Initial questions evaluated obstetrician demographics, practice type, and NIPT familiarity. Subsequent questions were designed to solicit current practices regarding aneuploidy screening as well as opinions, experiences, and implications of NIPT.

Results: Survey respondents identified NIPT as clinically superior to traditional screening methods and indicated that they would like ACOG to formally recommend NIPT for any pregnant woman. Insurance coverage, and therefore cost, was noted as the biggest barrier, and over 81% of surveyed providers would utilize NIPT as a first-line screening test if patients’ insurance offered full coverage. The majority of providers who have implemented NIPT into clinical practice indicated improved patient care. While most providers demonstrated accurate understanding of the technology and its application, nearly 15% misunderstood NIPT as being a diagnostic test for fetal aneuploidy.

Conclusion: The results of the survey suggest that there is a desire for changes to current practice guidelines and insurance coverage. Additionally, provider education remains paramount.     

An Update on Current Prenatal Testing Options: First Trimester and Noninvasive Prenatal Testing

Prenatal genetic testing is rapidly evolving and requires that prenatal care providers stay up‐to‐date with accurate, evidence‐based knowledge. Noninvasive prenatal testing (NIPT), first trimester maternal serum markers, and fetal nuchal translucency are the most recently developed screening tests added to the testing repertoire for detection of chromosomal disorders such as trisomy 21 (Down syndrome). NIPT is a new, highly accurate technique that uses maternal serum and is rapidly being introduced as a first trimester screening tool and increasingly being requested by pregnant women. The American College of Obstetricians and Gynecologists recommends that all pregnant women be offered first and second trimester screening options, regardless of risk status, but does not yet recommend NIPT. It is important for prenatal care providers to be aware of and understand these testing options in order to assist women and their families in making well‐informed decisions during pregnancy. The purpose of this article is to update midwives and other prenatal care providers on the current prenatal genetic testing options available and how to appropriately offer and discuss them with their clients. We discuss how these tests work; what to do with the results; and most importantly, how to support and communicate accurate information to women and families as they navigate through an increasingly complicated array of testing choices.     

无创产前基因检测在胎儿性染色体疾病筛查中的应用

目的探讨无创产前基因检测(non-invasive prenatal genetic testing,NIPT)在胎儿性染色体疾病中的临床价值。方法统计深圳市第二人民医院2016年3月至2019年6月行NIPT的16119例单胎孕妇中提示21-三体、18-三体、13-三体、性染色体异常和其他染色体异常的阳性率;对比2016年3月至2019年6月NIPT示“胎儿性染色体异常”与本院染色体核型结果。结果①NIPT对21-三体,18-三体,13-三体,性染色体异常和其他染色体异常筛查的阳性率分别为0.42%(68/16119),0.10%(16/16119),0.07%(11/16119),0.38%(61/16119)和0.22%(36/16119)。②47例“NIPT示胎儿性染色体异常”者中,确诊为性染色体疾病者26例,阳性预测值55.32%。其中,NIPT对胎儿性染色体数目偏多的阳性预测值为91.30%(21/23),对胎儿性染色体数目偏少的阳性预测值20.0%(4/20),对胎儿性染色体数目异常的阳性预测值25.0%(1/4)。结论NIPT可作为胎儿性染色体疾病的筛查方法,但由于其对性染色体偏少和性染色体数目异常的假阳性率较高,检测阳性者仍需要做侵入性产前诊断确诊。     

Nichtinvasive Pränataltestung (NIPT)

Non-invasive prenatal testing (NIPT) using cell-free fetal DNA (cff-DNA) in maternal blood has the potential to dramatically alter the way prenatal screening and diagnosis is delivered. Before NIPT can be implemented into routine practice, information is required on its costs and benefits. The best performing screening tests are able to identify more than 90?% of trisomy 21 cases with a 5?% rate of false positives but positive screening results require confirmation with diagnostic testing, such as amniocentesis or chorionic villus sampling (CVS). However, both sampling procedures are invasive, and are associated with significant risks to the fetus and mother, including the potential loss of a healthy fetus. For this reason invasive prenatal diagnosis tests are currently performed only in high-risk pregnancies or in pregnancies with increased maternal age and/or a family history of inherited disease. Therefore, developing a reliable method for NIPD for fetal trisomy 21 is of critical importance in prenatal care and NIPT is able to identify 99?% of trisomy 21 cases with a 0.1?% rate of false positives. As first-line testing NIPT detects more Down’s syndrome cases, results in fewer procedure-related miscarriages and is more expensive than current screening. When NIPT uptake increases, NIPT will detect more trisomy 21 cases with a small increase in procedure-related miscarriages and costs. As first-line testing NIPT is likely to produce more favorable outcomes but at greater cost. Further research is needed to evaluate NIPT under real world conditions.     

Validation of a method for noninvasive prenatal testing for fetal aneuploidies risk and considerations for its introduction in the Public Health System

Objective: The aim of this study was to validate noninvasive prenatal testing (NIPT) for fetal aneuploidies by whole-genome massively parallel sequencing (MPS).

Methods: MPS was performed on cell-free DNA (cfDNA) isolated from maternal plasma in two groups: a first set of 186 euploid samples and a second set of 195 samples enriched of aneuploid cases (n?=?69); digital PCR for fetal fraction (FF) assessment was performed on 178/381 samples. Cases with?<10?×?10⁶ reads (n?=?54) were excluded for downstream data analysis. Follow-up data (invasive testing results or neonatal information) were available for all samples. Performances in terms of specificity/sensitivity and Z-score distributions were evaluated.

Results: All positive samples for trisomy 21 (T21) (n?=?43), trisomy 18 (T18) (n?=?6) and trisomy 13 (T13) (n?=?7) were correctly identified (sensitivity: 99.9%); 5 false positive results were reported: 3 for T21 (specificity?=?98.9%) and 2 for T13 (specificity?=?99.4%). Besides FF, total cfDNA concentration seems another important parameter for MPS, since it influences the number of reads.

Conclusions: The overall test accuracy allowed us introducing NIPT for T21, T18 and T13 as a clinical service for pregnant women after 10?+?4 weeks of gestation. Sex chromosome aneuploidy assessment needs further validation due to the limited number of aneuploid cases in this study.     

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.     

Predictive value of increased nuchal translucency as a screening test for the detection of fetal chromosomal abnormalities

Objective.?The study aimed to estimate the incidence of increased nuchal translucency in the first trimester ultrasound scan results (cut-off limit 2.5 mm) and to evaluate the predictive value of increased nuchal translucency as a screening test for the detection of fetal chromosomal abnormalities.

Methods.?We used the ultrasound scan results of nuchal translucency evaluation and the results of chromosomal analysis of the invasive prenatal control performed as a result of increased nuchal translucency.

Results.?We collected 2183 nuchal translucency ultrasound scans in which we detected 21 embryos with a pathologic value (0.96%). We collected the data of 168 cases of invasive prenatal control due to increased nuchal translucency from which 122 cases were found. A total of 122 cases of pregnant women undergone an invasive prenatal diagnostic method due to increased nuchal translucency, of which 11 fetuses were found with trisomy 21 (Down syndrome) (9%), 3 fetuses with trisomy 13 (Patau syndrome) (2.45%), 3 fetuses with monosomy 45XO (Turner syndrome) (2.45%) and 1 fetus with translocation (0.8%).

Conclusions.?The positive predictive value of the increased fetal nuchal translucency as a screening test for the detection of fetal chromosomal abnormalities based on the results of the chromosomal-genetic analysis of the invasive prenatal diagnostic procedures is 14.8%.     

Prenatal diagnosis versus first-trimester screening of trisomy 21 among pregnant women aged 35 or more

Objective: To compare the policy of prenatal diagnosis versus first trimester screening of trisomy 21 among pregnant women of advanced age.

Methods: A retrospective study was conducted on patients aged ≥35 divided in two groups: patients who requested first trimester combined test and only in case of screen-positive result underwent invasive testing (group A); patients undergoing chorionic villous sampling or amniocentesis as first investigation (group B). The following outcome variables were compared: antenatal detection of trisomy 21, occurrence of trisomy 21 at birth, miscarriage rate, hospitals' costs.

Results: 4527 women were included. Of these, 534 (11.80%) underwent T21 screening whereas 3993 (88.20%) requested primary invasive testing. In group A, 64 combined test were positive (11.99%) and 8 trisomy 21 cases were diagnosed (1.50%); the loss of euploid fetuses after invasive procedure was 4.55% (2/44). No false-negative case was observed. In group B 57 cases of trisomy 21 were diagnosed (1.43%), and pregnancy loss rate of chromosomally normal fetuses was 0.45% (17/3806). The estimated cost was, respectively, 67.720€ for the primary screening versus 1.996.500€ for direct prenatal diagnosis.

Conclusion: First trimester screening of trisomy 21 is highly accurate and cost saving among women ≥35.     

A two-year experience of non-invasive prenatal testing (NIPT) at an urban tertiary medical center in South Korea

ObjectiveTo report our experience of implementing non-invasive prenatal testing (NIPT) in a tertiary urban academic medical center in South Korea.Materials and methodsAn observational retrospective study of singleton and twin pregnancies that underwent prenatal screening for fetal aneuploidy from July 2016 to April 2018 was conducted. Demographics of the study population electing NIPT versus those opting the integrated test were compared. We also assessed clinical significant factors influencing cfDNA fetal fraction in NIPT.ResultsAmong the 817 women who underwent serum screening tests during the study period, 490 women (60.0%) chose the integrated test while 327 women (40.0%) chose NIPT. Compared to the integrated test group, women in the NIPT group were older (mean age 34.7 ± 3.7 vs. 32.6 ± 3.4; p-value < 0.01), multiparous (47.1% vs. 39.8%; p-value = 0.046), and had higher rate of previous abortion history (28.4% vs. 21.6%; p-value = 0.033). A significant decrease in the number of invasive diagnostic tests was observed since the adoption of NIPT. The screen negative and positive rates of the integrated test group for fetal aneuploidy were 95.3% and 4.7%, respectively while those of the NIPT group were 95.9% and 1.2%, respectively. The rate of inadequate cfDNA fetal fraction was 3.0%. Low fetal fraction was associated with higher maternal age, body weight and BMI.ConclusionsThe implementation of NIPT has significantly affected the practice pattern of prenatal aneuploidy screening by replacing the integrated test and decreasing invasive diagnostic tests.     

Sensitivity of prenatal ultrasound for detection of trisomy 18

Objectives: To evaluate the sensitivity of prenatal ultrasound (US) for trisomy (T18) diagnosis and describe US findings in a large tertiary care institution in the USA.

Materials and methods: This was a retrospective cohort of all T18 cases diagnosed at our institution from October 2004 to October 2014 based on prenatal or postnatal genetic diagnostic testing. We included all women with a fetus affected by T18 who had a comprehensive US by a maternal–fetal medicine specialist performed at our institution. US findings were reviewed, classified by organ system, and categorized as an anomaly or soft marker. Chi-square or t-test was used for statistical analysis.

Results: We included 128 cases of T18 with confirmed cytogenetic analysis ?110 (86%) of which were diagnosed prenatally or suspected by cell-free DNA and confirmed postnatally, and 18 of which underwent neonatal blood sampling alone. One hundred and twenty-one (95%) had at least one abnormal US finding. Anomalies were more frequently identified on US at ≥20 weeks as compared with <20 weeks (93% versus 76%; p?=?.004). The mean number of findings detected per fetus was 5.1?±?3.0. Fetuses diagnosed by postnatal sampling alone had a similar number of US exams performed and number of abnormal findings compared to those diagnosed prenatally.

Conclusion: Ninety-five percent of fetuses with T18 had at least one abnormal US finding. This sensitivity of is higher than reported in most prior studies, but is not 100%, and should be considered when counseling women regarding prenatal diagnosis of T18.

Rationale: Historical detection rates for abnormal sonographic findings in trisomy 18 fetuses range from 70% to 100%. These studies are limited by small sample sizes. This is a contemporary study of ultrasound findings in a large group of women with confirmed trisomy 18 by prenatal or postnatal genetic diagnosis. We provide expansive detail on soft markers and anomalies broken down by organ-system and gestational age.