Abstract: Background Prenatal screening for congenital heart disease (CHD) can not only reduce the number of critical birth defects with poor prognosis, but also facilitate the early evaluation, tracking and management of CHD fetuses. Objective To investigate the diagnostic accuracy of fetal CHD by ultrasound screening in the first and second trimester. Design Diagnostic test accuracy. Methods This research covers the pregnant women and their fetuses who registered, received examinations and gave birth in Jiangsu Kunshan Maternity and Child Care Centre between Aug.2018 and Dec. 2021. The fetal or neonatal cardiac ultrasound was used as the gold standard for diagnosis, and the standard to be further tested was the positive ultrasound result in the first and second trimesters. Main outcome measures Diagnostic accuracy parameters. Results During the study period, a total of 18 326 pregnant women underwent birth examination in our hospital, among which 3 534 (19.3%) had incomplete delivery data, and 14 960 fetal data were included in the analysis. Among 882 fetuses positive for ultrasound screening in the first and second trimester, 92 were lost to followup (10.2%), and 790 fetuses underwent ultrasound, cardiac ultrasound, or chromosome examination with induced labor and abortion in 182 cases. Of the 608 live births, 103 were diagnosed with CHD by fetal echocardiography and 4 were diagnosed with CHD by postnatal echocardiography.Based on 14 868 cases of fetal CHD screening, 171 cases were true positive, 48 cases were false negative, 14 030 cases were true negative, and 619 cases were false positive. The sensitivity was 78.1%(95%CI:71.9%83.3%), and the specificity was 95.8%(95%CI:95.4%96.1%). The false negative rate was 21.9%(95%CI: 16.7%28.1%).There were 14 078 negative fetuses in the first and second trimester of pregnancy with no lost followup cases, and 505 fetuses in the first and second trimester of pregnancy with positive ultrasound screening but normal results by cardiac ultrasound or chromosome examination. Screened by dual index method after birth, 14 335 negative fetuses and 244 positive fetuses were found, and 52 CHD cases were confirmed by neonatal cardiac ultrasound.In 219 cases of confirmed CHD, (1) CHD featured by atrial septal defect (secondary perforation) and congenital bilobal aortic valve malformation could not be found by fetal ultrasound and needed to be diagnosed by neonatal ultrasound; (2) Among 64 cases of induced labor, the 100% induced labor rate was found in CHD of complex type, right ventricular double outlet, ventricular septal defect (coarctation of aorta), atrial septal dilatation tumor, aortic valve stenosis, aortic arch rupture, pulmonary artery suspension, absence of inferior vena cava, ventricular septal defect (pulmonary stenosis), endocardial fibroplasia, right heart dysplasia, single ventricle, severe tricuspid valve stenosis, right pulmonary artery abnormality originating from the ascending aorta, and 80% induced labor rate was found in CHD of tetralogy of Fallot (8/10), complete atrioventricular septal defect (5/6), complete transposition of great arteries (4/5);(3)There were 9 cases of CHD with chromosomal abnormalities with 2 cases of ventricular septal defect (2.4%), 1 case of complex CHD (5%), 1 case of tetralogy of Fallot (10%), 1 case of right heart dysplasia (50%), and 1 case of single ventricle (100%). Conclusions After CHD screening in the first and second trimester, even fetuses with negative screening should be screened with two indicators after birth. Fetuses with positive screening should be closely examined with fetal cardiac ultrasound so as to fully realize the integrated prenatal and postpartum management mode of CHD.

Key words: Ultrasound screening, Congenital heart disease (CHD), Referral