Fetal heart assessment on routine first-trimester ultrasound scan.

Introduction. Screening for congenital heart defects (CHD) in the first trimester has been shown to be effective in low risk populations. However, it is usually not per formed routinely. Our aim was to assess the feasibility of the fetal heart assessment and screening for major CHD by routine first trimester scan. Materials and method. This was a retrospective two year study of 1423 uncomplicated pregnancies, examined during the first trimester screening for chromosomal and fetal structural abnormalities. To improve the fetal heart visualization on anatomic survey, we have performed the scans starting from 12 gestational weeks. The four chamber view (4CV) and three vessels and trachea view (3VTV) of fetal hearts were assessed by grayscale and color or directional power Doppler imaging. The final diagnosis of the suspected CHD was based on the second trimester and third trimester fetal and postnatal echocardiography or autopsy. Results and conclusions. The median crown rump length was 61.7 mm. The 4CV and the 3VTV were considered normal in 95% of cases (1352/1423), in 2% of cases (29/1423) unfeasible, and in 3% of cases (42/1423) abnormal. Overall, on the first trimester scan we identified 42 cases of CHD, and among them there were 33 (2.32%) confirmed major CHD, as fol lows: eight cases of double outlet right ventricle (DORV); eight atrioventricular septal defects (AVSD); five cases of pulmonary atresia; four cases of tetralogy of Fallot (TOF); four cases of hypoplastic left heart syndrome; two cases of pulmonary stenosis; two cases of mitral atresia and one mitral stenosis; one case of tricuspid atresia; one case of transposition of great arteries (TGA), one aortic hypoplasia, one case of critical stenosis of the aorta, and three cases of right atrial isomerism. Among the confirmed congenital heart defects, seven were complex cardiac anomalies. In four cases, the diagnosis was slightly modified later in gestation. In addition, 14 congenital heart defects were missed in the first trimester, as follows: four cases of aortic hypoplasia, two TOF, two TGA, two DORV, two cases of coarctation of the aorta, one pulmonary atresia and one right aortic arch. The assessment by the 4CV and the 3VTV for major congenital heart defects had a sensitivity and specificity of 70.2% and 99.3%, respectively, with a positive and negative predictive value of 78.5% and 98.9%, respectively. Among 33 fetuses with CHD, seven fetuses (20.6%) had other structural abnormalities. In 15 fetuses (44.11%), the NT was above the 95th centile. Eleven fetuses (32.35%) showed reversed flow in ductus venosus and/or tricuspid regurgitation. First trimester cardiac screening and the detection of major congenital heart defects are feasible during the routine first trimester scan. However, the early detailed assessment of the fetal heart requires expertise in fetal echocardiography and complementary scans in both the second and the third trimester, since there are many defects that evolve over time which are best assessed later in gestation. [ABSTRACT FROM AUTHOR]