Cell-free DNA screening in twin pregnancies.

Cell-free DNA (cfDNA) screening for fetal aneuploidies is clinically available and exhibits better performance than conventional serum screening tests. However, data on the clinical performance of cfDNA screening in twin pregnancies are limited. In this review, we summarized the clinical performance and evaluated the feasibility of cfDNA screening in twin pregnancies based on recent studies and recommendations. The performance of cfDNA screening for trisomy 21 in twin pregnancies is similar to that in singleton pregnancies. Specifically, cfDNA screening has a higher detection rate and lower false-positive rate compared with conventional serum screening. Consequently, recent international guidelines from several academic communities have recommended that cfDNA screening for aneuploidy in twin pregnancies could be considered. Moreover, twin pregnancies can present with specific conditions, such as different zygosities and vanishing twins; therefore, individualized counseling and management are required. Further clinical studies with more twin pregnancies are required for a more accurate analysis.

Prenatal Diagnosis of Congenital Heart Diseases and Associations with Serum Biomarkers of Aneuploidy: A Multicenter Prospective Cohort Study.

PURPOSE: We assessed prenatal detection rates of congenital heart disease (CHD) and associations between maternal serum biomarkers and non-chromosomal CHD in singleton pregnancies. MATERIALS AND METHODS: This study was conducted as a secondary analysis of data obtained during a multicenter prospective cohort study that investigated the cost-effectiveness of prenatal testing for fetal aneuploidy. We analyzed the prenatal detection rate and accuracy for CHD screening via ultrasound during the second trimester, as well as associations between serum biomarkers and CHDs, in singleton newborns without chromosomal abnormalities. RESULTS: Among 6715 women, 142 (2.1%) newborns were born with CHDs, of which 67 (1.0%) newborns had major CHDs. The prenatal detection rate for all CHDs and major CHDs were 34.5% and 58.2%, respectively. After excluding isolated ventricular septal defects, the detection rate for critical CHDs was 85.9%. Women with low pregnancy-associated plasma protein A (PAPP-A) (<0.4 multiples of the median, MOM) face increased risks of non-chromosomal CHDs [adjusted odds ratio (aOR) 2.76; 95% confidence interval (CI) 1.36-5.13] and major CHDs (aOR 7.30; 95% CI 3.18-15.59), compared to those without CHDs. A higher inhibin A level (≥2.5 MOM; aOR 4.84; 95% CI 1.42-12.46) was associated with non-chromosomal major CHDs. CONCLUSION: Ultrasonography performed during the second trimester by obstetricians detected over 85% of critical CHDs. Low maternal serum PAPP-A or high inhibin-A was associated with non-chromosomal CHDs. These results may contribute to an improvement in prenatal diagnosis of CHDs.

Clinical Significance of Velamentous Cord Insertion Prenatally Diagnosed in Twin Pregnancy.

BACKGROUND: The purpose of this study was to evaluate the prevalence of velamentous cord insertion (VCI) and the actual association between pathologically confirmed VCI and perinatal outcomes in twins based on the chorionicity. METHODS: All twin pregnancies that received prenatal care at a specialty clinic for multiple pregnancies, from less than 12 weeks of gestation until delivery in a single institution between 2015 and 2018 were included in this retrospective cohort study. RESULTS: A total of 941 twins were included in the study. The prevalence of VCI in dichorionic (DC) twins and monochorionic diamniotic (MCDA) twins was 5.8% and 7.8%, respectively (p = 0.251). In all study population, the prevalence of vasa previa and placenta accreta spectrum was higher in VCI group than that of non-VCI group (p = 0.008 and 0.022). In MCDA twins with VCI, birth weight, 1 and 5-min Apgar score were lower than DC twins with VCI (p = 0.010, 0.002 and 0.000). There was no significant association between VCI and selective fetal growth restriction (p = 0.486), twin-to-twin transfusion syndrome (p = 0.400), and birth-weight discordance (>20% and >25%) (p = 0.378 and 0.161) in MCDA twins. CONCLUSION: There was no difference in the incidence of VCI in twins based on the chorionicity. Moreover, VCI was not a risk factor for adverse perinatal outcomes excepting vasa previa and placenta accreta spectrum, which had a high incidence in twins with VCI.

Clinical Utility of Increased Nuchal Translucency at 11-13 Weeks of Gestation in Twin Pregnancies Based on the Chorionicity.

To assess clinical implications of increased nuchal translucency (INT) in twin pregnancies based on the chorionicity. This was a retrospective review of the twin pregnancies who underwent first trimester ultrasound with nuchal translucency (NT) measurement at 11-13 weeks of gestation from January 2006 to December 2014. Data were collected using the OB database and the chart review. Pregnancy outcomes, including gestational weeks at the delivery, abnormal fetal karyotypes, fetal structural anomalies, and twin-specific complications, were analyzed. A total of 1622 twin pregnancies with INT ≥ 95th percentile in one or both fetuses were identified. In all twin pregnancies with INT, abnormal fetal karyotypes were identified in 17 (8.6%) patients (odds ratio = 13.28, CI = 5.990-29.447, p = 0.000) and twin-specific complications were identified in 23 (11.6%) patients (odds ratio = 2.398, CI = 1.463-3.928, p = 0.001) compared to those with normal NT. Among the INT group, when the groups were subdivided into monochorionic (MC) and dichorionic (DC) pregnancies, 14.8% and 29.6% of the MC pregnancies had structural anomalies in one or both fetuses (odds ratio = 5.774, 95% CI = 1.445-23.071, p = 0.01) and twin-specific complications (odds ratio = 4.379, 95% CI = 1.641-11.684, p = 0.03), respectively, compared to DC pregnancies with 2.9% for structural anomalies and 8.8% for twin-specific complications. The prevalence of abnormal fetal karyotypes was not statistically different in patients with INT when compared between MC and DC pregnancies (p = 0.329). INT was associated with a higher rate of twin-specific complications and fetal structural anomalies in MC twin pregnancies rather than abnormal fetal karyotype. Therefore, NT measurement in MC twin pregnancies can be a useful tool for predicting adverse pregnancy outcomes. Appropriate counseling and surveillance based on the chorionicity are imperative in the prenatal care of twin pregnancies.