First-Trimester Screening For Fetal Structural And Chromosomal Anomalies By A Detailed Early Anomaly Scan

Objective:To assess the performance of first trimester ultrasound screening for fetal structural and chromosomal anomalies based on a detailed anomaly and nuchal translucency(NT)scan at 11-13+6 weeks’ gestation;To assess the potential clinical applicability of cardiac axis and V sign angle measurements for detection of major congenital heart defects in the first trimester.Methods:A prospective cohort study was conducted at Nanjing Drum Tower hospital.Fetuses with crown rump length(CRL)between 45mm and 84mm at our hospital were enrolled from December 2015 to August 2016.Crown rump length,NT,fetal heart rate,cardiac axis on the four chamber view and the V sign angle on the three vessels and trachea view were measured and fetal head,neck,spine,thorax,heart,abdominal wall,limbs and umbilical cords were assessed during the scan.After thr detailed first-trimester anomaly scan followed the protocol of systematic standardized scan planes fetal congenital abnormalities were compared to those at 20-24 weeks and postnatal examination.Results:1.2252 fetuses were enrolled with 110(4.9%)fetal abnormalities detected including 59 cases of cardiac defects,11 cases of anomalies in uterine system,11 cases of skeletal anomalies,8 cases anomalies in central nervous system,7 cases of cleft lip or palate,4 cases of abdominal wall defects,4 cases of cervix lymphatic hygroma,2 cases of anomalies in digestive system,2 cases of conjoined twins,1 case of umbilical cord cyst and 1 case of amniotic band syndrome.2.The detection rate of major structural abnormality and chromosomal anomalies in screening based on NT was 23.6%(26 of 110)and 70.6%(12 of 17)respectively.3.The first-trimester scan detection rate for structural anomalies was 60.0%(66 of 110),including all cases of cervix lymphatic hygroma,abdominal wall defects,cleft lip or palate,conjoined twins,umbilical cord cyst and amniotic band syndrome.The detection rate of central nervous system and cardiac defects were 75.0%(6 of 8)and(33 of 59)respectively.The detection rate of anomalies in digestive system,skeletal system and uterine system was 50%(1 of 2),45.5%(5 of 11),18.2%(2 of 11).4.17 chromosomal abnormalities were identified and 15 were detected in the first trimester including 4 cases of Turner syndrome,2 cases of Trisomy 21,7 cases of Trisomy 18,1 case of Trisomy 21 and 20,1 case of Y chromosome duplication.5.When isolated septal wall defects were excluded,the nuchal translucency above 95th percentile,abnormal cardiac axis or V sign angle was observed in 59.4%(19 of 32),62.5%(20 of 32),68.8%(22 of 32)of fetuses with cardiac defects respectively.Either abnormal cardiac axis or V sign angle was found in 93.8%(30 of 32)of the fetuses with cardiac defects.Conclusion:1.Detailed anomaly and NT scan in the first trimester can increase the detection rate of fetal structural and chromosomal anomalies compared to traditional NT scan and decrease the gestational age of termination severe fetal abnormalities compared to second trimester anomaly scan.2.Abnormal cardiac axis and V sign angles in the first trimester can increase the detection rate of fetal major congenital heart diseases compared to traditional NT scan.