The femur too short? 1373 fetuses with short femur during second-trimester screening

Purpose A short fetal femur in prenatal diagnosis might be an indicator for intrauterine growth retardation (IUGR), a genetically determined small child (SGA) with or without associated fetal malformations and/or an adverse fetal outcome. Methods 1373 singleton pregnancies with a femoral length < 5th percentile detected between 1999 and 2015 during second-trimester screening in a tertiary prenatal diagnostic center were subjected to a descriptive retrospective analysis with regard to fetal characteristics as well as pregnancy outcome. Results 685 (49.9%) fetuses presented an isolated short femur, while 688 (50.1%) showed additional abnormalities. 293 (42.6%) of those were SGA babies without any malformation, while 395 (57.4%) had one or more severe anomaly of the following organ systems: 157 (11.5%) cardiovascular, 101 (7.4%) musculoskeletal, 82 (6.0%) urogenital, 72 (5.2%) cerebrocephalic, 50 (3.6%) gastrointestinal, and 5 (0.4%) thoracic. 75 (5.5%) of the fetuses showed chromosomal aberrations of which Trisomy 13, 18 and 21 were found in 2, 13 and 27 of the cases, respectively. Fetuses with associated malformations had a significantly lower live birth rate than those without (64.2% vs. 98.1%, p < 0.001); in addition, a higher rate of preterm births 36.6% vs. 11.3%, p < 0.001) and SGA babies (51.4% vs. 30.4%, p < 0.001) were observed in the first collective. Conclusion Diagnosis of a short fetal femur should lead to an extended organ screening; in the case of associated abnormalities, additional genetic testing has to be offered, as well as intensified pregnancy monitoring in pregnancies at risk for IUGR and/or preterm birth.

Prevalence of common aneuploidy in twin pregnancies

The incidence of chromosomal abnormalities in twin pregnancies is not well-studied. In this retrospective study, we investigated the frequency of chromosomal abnormalities in twin pregnancies and compared the incidence of chromosomal abnormalities in dichorionic diamniotic (DD) and monochorionic diamniotic (MD) twins. We used data from 57 clinical facilities across Japan. Twin pregnancies of more than 12 weeks of gestation managed between January 2016 and December 2018 were included in the study. A total of 2899 and 1908 cases of DD and MD twins, respectively, were reported, and the incidence of chromosomal abnormalities in one or both fetuses was 0.9% (25/2899) and 0.2% (4/1908) in each group (p = 0.004). In this study, the most common chromosomal abnormality was trisomy 21 (51.7% [15/29]), followed by trisomy 18 (13.8% [4/29]) and trisomy 13 (6.9% [2/29]). The incidence of trisomy 21 in MD twins was lower than that in DD twins (0.05% vs. 0.5%, p = 0.007). Trisomy 21 was less common in MD twins, even when compared with the expected incidence in singletons (0.05% vs. 0.3%, RR 0.15 [95% CI 0.04–0.68]). The risk of chromosomal abnormality decreases in twin pregnancies, especially in MD twins.

Clinical evaluation of non-invasive prenatal screening in 32,394 pregnancies from Changzhi Maternal and Child Health Care Hospital of Shanxi China

Non-invasive prenatal screening (NIPS)was performed in 32,394 pregnancies, out of which results were available in 32,361 (99.9%) of them.Among the 32,361confirmed samples, 164 cases had positive results and 32197 cases had negative results. Of these positive cases, 116 cases were trisomy 21, 34 cases were trisomy 18 and 14 cases were trisomy 13. No false negative results were found in this cohort. The overall sensitivity and specificity were 100% and 99.91%, respectively. There was no significant difference in test performance between the 7,316 high-risk and 25,045 low-risk pregnancies，(sensitivity, 100% vs 100% (P >0.05); specificity, 99.96% vs 99.95% (P > 0.05)). Factors contributing to false-positive results included fetal CNVs, fetal mosaicism and typically producing Z scores between 3 and 4. Moreover, we analyze NIPT whole-genome sequencing to investigate the Single Nucleotide Polymorphisms (SNPs) associations with drug response or risk of disease. As compare to the 1000g East Asian genome data, the results reveal a significant difference in 7,285,418 SNPs variants of Shanxi pregnant women including 19，293 clinvar recorded variants and 7,266,125 non- clinvar recorded. Our findings showed that NIPS was an effective assay that may be applied as routine screening for fetal trisomies in the prenatal setting. In addition, this study also provides an accurate assessment of significant differencein 7,285,418 SNPs variants in Shanxi pregnant women that were previously unavailable to clinicians in Shanxi population.

Noninvasive Prenatal Screening Based on Second-Trimester Ultrasonographic Soft Markers in Low-Risk Pregnant Women

Background: We aimed to assess the clinical application of noninvasive prenatal screening (NIPS) based on second-trimester ultrasonographic soft markers (USMs) in low-risk pregnant women.Methods: Data of pregnant women between April 2015 and December 2019 were retrospectively analyzed. Pregnant women [age at expected date of confinement (EDC) of &lt;35 years; low risks for trisomy 21 (T21) and trisomy 18 (T18) based on maternal serum screening; presenting second-trimester USMs (7 types)] who successfully underwent NIPS and had available follow-up information were included in our study. Cases with positive NIPS results were prenatally diagnosed. All patients were followed up for 6 months to 2 years after NIPS, and their clinical outcomes were obtained. Subgroup analyses were performed according to the different USMs.Results: NIPS suggested that among a total of 10,023 cases, 37 (0.37%) were at high risk of aneuploidy, including 4 T21, 6 trisomy 13 (T13), and 27 sex chromosome abnormalities (SCA). Ten cases with aneuploidy (0.10%) were confirmed by prenatal diagnosis, consisting of two T21 and eight SCA. The eight fetuses with SCA consisted of one monosomy X, two XXY, one XXXY, one XXX, one XYY, and two mosaicisms. T21 was detected in one fetus with absent or hypoplastic nasal bone and one fetus with echogenic intracardiac focus (EICF). SCA was detected in five fetuses with EICF, two fetuses with multiple soft markers, and one fetus with echogenic bowel. The positive rate of chromosomal aneuploidy was significantly higher in fetuses with absent or hypoplastic nasal bone (6.25 vs. 0.10%, p = 0.017), echogenic bowel (3.7 vs. 0.10%, p = 0.029), and multiple soft markers (0.678 vs. 0.10%, p = 0.045) than in the total fetuses. The positive predictive values (PPVs) of NIPS in these three groups were 100%, 50%, and 100%, respectively. EICF accounted for 93.25% (9,346/10,023) of the study population, whereas the PPV of NIPS was only 20%.Conclusion: NIPS is an advanced screening test for low-risk pregnant women. In the 10,023 pregnant women sampled, SCA were more common than autosomal trisomy, and EICF was the most frequent USM but the least predictive aneuploidy. Further aneuploidy evaluation is suggested for low-risk pregnant women whose ultrasound indicates absent or hypoplastic nasal bone, echogenic bowel, or multiple soft markers. NIPS can serve as a second-line complementary screening for these women.

Systematic evaluation of NIPT aneuploidy detection software tools with clinically validated NIPT samples

Non-invasive prenatal testing (NIPT) is a powerful screening method for fetal aneuploidy detection, relying on laboratory and computational analysis of cell-free DNA. Although several published computational NIPT analysis tools are available, no prior comprehensive, head-to-head accuracy comparison of the various tools has been published. Here, we compared the outcome accuracies obtained for clinically validated samples with five commonly used computational NIPT aneuploidy analysis tools (WisecondorX, NIPTeR, NIPTmer, RAPIDR, and GIPseq) across various sequencing depths (coverage) and fetal DNA fractions. The sample set included cases of fetal trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome). We determined that all of the compared tools were considerably affected by lower sequencing depths, such that increasing proportions of undetected trisomy cases (false negatives) were observed as the sequencing depth decreased. We summarised our benchmarking results and highlighted the advantages and disadvantages of each computational NIPT software. To conclude, trisomy detection for lower coverage NIPT samples (e.g. 2.5M reads per sample) is technically possible but can, with some NIPT tools, produce troubling rates of inaccurate trisomy detection, especially in low-FF samples.

Cardiac Interventions for Patients With Trisomy 13 and Trisomy 18: Experience, Ethical Issues, Communication, and the Case for Individualized Family-Centered Care

This report is informed by the themes of the session Trisomy 13/18, Exploring the Changing Landscape of Interventions at NeoHeart 2020—The Fifth International Conference of the Neonatal Heart Society. The faculty reviewed the present evidence in the management of patients and the support of families in the setting of trisomy 13 and trisomy 18 with congenital heart disease. Until recently medical professionals were taught that T13 and 18 were “lethal conditions” that were “incompatible with life” for which measures to prolong life are therefore ethically questionable and likely futile. While the medical literature painted one picture, family support groups shared stories of the long-term survival of children who displayed happiness and brought joy along with challenges to families. Data generated from such care shows that surgery can, in some cases, prolong survival and increase the likelihood of time at home. The authors caution against a change from never performing heart surgery to always—we suggest that the pendulum of intervention find a balanced position where all therapies including comfort care and surgery can be reviewed. Families and clinicians should typically be supported and empowered to define the best care for their children and patients. Key concepts in communication and case vignettes are reviewed including the importance of supportive relationships and the fact that palliative care may serve as an additional layer of support for decision-making and quality of life interventions. While cardiac surgery may be beneficial in some cases, surgery should not be the primary focus of initial family education and support.

Umbilical artery pulsatility index and half-peak systolic velocity in second- and third-trimester fetuses with trisomy 18 and 13

Objectives To analyze umbilical artery (UA) Doppler velocimetry and its possible role in placenta-mediated fetal growth restriction (FGR) in second- and third-trimester fetuses with trisomy 18 and 13. Methods UA pulsatility index (PI) and half-peak systolic velocity deceleration time (hPSV-DT) were measured in fetuses with trisomy 18 and 13. Correlation with gestational age, birthweight, and perinatal outcome was analyzed. Results A total of 80 measurements were taken from 33 fetuses with trisomy 18 and 19 with trisomy 13. Overall, there was a high prevalence of abnormal UA Doppler velocimetry. In fetuses with trisomy 18, 54% (27/50) of the UA PI values and 58% (29/50) of the UA hPSV-DT values were abnormal. In fetuses with trisomy 13, 80% (24/30) of the UA PI values and 87% (26/30) of the UA hPSV-DT values were abnormal. The prevalence of abnormal UA Doppler velocimetry increased with gestational age in both types of aneuploidy. However, this trend was only significant for trisomy 13 (p<0.05). All fetuses with trisomy 18 and 86% of fetuses with trisomy 13 were classified at birth as FGR. There were no perinatal survivors in this series. Conclusions A high prevalence of abnormal UA Doppler velocimetry was found in second- and third-trimester fetuses with trisomy 18 and 13, which further increased with gestational age. These results may well correlate with alterations described previously in the placenta, suggesting placental insufficiency has an important role in the development of FGR in these autosomal aneuploid fetuses.

Expanding the application of non-invasive prenatal testing in the detection of foetal chromosomal copy number variations

Purpose The aim of this study was to assess the detection efficiency and clinical application value of non-invasive prenatal testing (NIPT) for foetal copy number variants (CNVs) in clinical samples from 39,002 prospective cases. Methods A total of 39,002 pregnant women who received NIPT by next-generation sequencing (NGS) with a sequencing depth of 6 M reads in our centre from January 2018 to April 2020 were enrolled. Chromosomal microarray analysis (CMA) was further used to diagnose suspected chromosomal aneuploidies and chromosomal microdeletion/microduplication for consistency assessment. Results A total of 473 pregnancies (1.213%) were positive for clinically significant foetal chromosome abnormalities by NIPT. This group comprised 99 trisomy 21 (T21, 0.254%), 30 trisomy 18 (T18, 0.077%), 25 trisomy 13 (T13, 0.064%), 155 sex chromosome aneuploidy (SCA, 0.398%), 69 rare trisomy (0.177%), and 95 microdeletion/microduplication syndrome (MMS, 0.244%) cases. Based on follow-up tests, the positive predictive values (PPVs) for the T21, T18, T13, SCA, rare trisomy, and MMS cases were calculated to be 88.89%, 53.33%, 20.00%, 40.22%, 4.88%, and 49.02%, respectively. In addition, the PPVs of CNVs of < 5 Mb, 5–10 Mb, and > 10 Mb were 54.55%, 38.46%, and 40.00%, respectively. Among the 95 cases with suspected CNVs, 25 were diagnosed as true positive and 26 cases as false positive; follow-up prenatal diagnosis by CMA was not performed for 44 cases. Moreover, among the 25 true positive cases, 10 were pathogenic, 3 were likely pathogenic, and 12 were of uncertain significance. Conclusion NIPT is not only suitable for screening T21, T18, T13, and SCA but also has potential significance for CNV detection. As combined with ultrasound, extended NIPT is effective for screening MMS. However, NIPT should not be recommended for whole-chromosome aneuploidy screening.