To investigate the clinical value of fetal ultrasonography in the screening of congenital heart malformations in twins at 11-13^{+ 6} weeks of gestation.

A retrospective cohort study method was used.Cases were collected from Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing Maternal and Child Health Care Hospital (January 2012 to December 2016) and the Fourth Hospital of Shijiazhuang City (January 2014 to December 2018). The twins with singleton or twins with cardiac malformation were screened out as the cardiac malformation group, and the twins with normal delivery during the same period were selected as the control group. Ultrasound data such as the nuchal translucency (NT), crown-rump-length (CRL), chorionicity, conception method, NT discordance, CRL discordance, NT discordance ≥20% incidence rate between twins, and the CRL discordance ≥10% incidence rate between twins in the two groups at 11-13^{+ 6} weeks were compared and analyzed.

①There were 30 cases in the cardiac malformation group (including 27 twins with singleton cardiac malformation and 3 twins with twin cardiac malformation) and 1 906 cases in the control group. ②The incidence rates of NT value ≥95th percentile and NT value ≥99th percentile in one or two pregnancies were significantly higher in the cardiac malformation group than in the control group (20.00% vs 2.20%, P<0.001; 10.00% vs 0.63%, P=0.002), the area under the ROC curve (AUC) for cardiac malformation screening was 0.589 and 0.549, respectively; CRL discordance in cardiac malformation group was higher than that in control group (P=0.018), the incidence of CRL discordance ≥10% in the cardiac malformation group was higher than that in the control group (26.67% vs 12.70%, P=0.024), the AUC of cardiac malformation screening was 0.570; there were no significant differences in the incidence of NT discordance, the incidence of NT discordance ≥20%, pregnancy pattern and chorionicity between the two groups (all P>0.05). ③Multivariate Logistic regression analysis was performed using the incidence rates of NT value ≥95% and NT value ≥99%, CRL discordance ≥10%, and NT discordance ≥20%. The incidences of fetal NT value ≥95% and NT value ≥99% were risk factors for cardiac malformation in twins (OR=11.095, 105.778; 95%CI=4.311-28.558, 16.984-658.796).

Ultrasound at 11-13^{+ 6} weeks of gestation showing thickened value of one or two fetuses, and the CRL discordance≥10%, indicates an increased risk of cardiac malformation in the twins; NT value ≥95% and NT value ≥99% is a risk factor for heart defects in twins.

Ultrasonography; Prenatal diagnosis; Twin pregnancy; Cardiac malformation; Nuchal translucency; Early pregnancy