To investigate the methodology and image characteristics of transabdominal echocardiography in diagnosing fetal congenital heart diseases in the first trimester.

Total 1288 pregnancies with high risk factor underwent transabdominal echocardiography and were diagnosed as congenital heart diseases during the 13th week of gestation from June 2012 to April 2015. We analyzed manifestation and classification feature in echocardiography of fetal congenital heart disease, and followed entire pregnancy and clinical outcome of all pregnant women selected.

Sixteen (1.2%, 16/1288) cases were diagnosed as congenital heart disease by echocardiography and were confirmed by clinic. Eleven cases were complex congenital heart diseases and 5 cases were single congenital heart diseases. Manifestations in echocardiography of fetal congenital heart disease were as followed in the first trimester: (1) Two cases of tetralogy of Fallot showed: slightly widened aorta without typical aortic riding sign, ventricular septal defect and pulmonary stenosis without branch. (2) Two cases of hypoplastic left heart syndrome showed: significant small left heart, enlarged right heart, mitral valve atresia, ventricular septal defect, slightly stenosed aorta with increased blood flow rate and pulmonary artery dilation. (3) Two cases of truncus arteriosus-I showed: only one large vessel in heart bottom without branch and ventricular septal defect. (4) Four cases of complele atrioventricular septal defect showed: no endocardial cross structure and common atrioventricular valve. (5) One case of single ventricle showed: single ventricle without ventricular septum. (6) One case of aortic coarctation showed: left ventricular smaller than normal and aortic isthmus stenosis in 16 week of gestation which were normal in the 13th week of gestation. (7) Four cases of ventricular septal defect showed: interruption of ventricular septal continuity and increased echogenicity of broken ends margin. One case of small ventricular septal defect was misdiagnosised. One case of ventricular septal defect and one case of forever left vena cava were missed. Eleven cases of pregnancy were interrupted and 5 cases delivered after diagnosised, of which the results of transabdominal ultrasound were confirmed with follow-up.

Transabdominal echocardiography can diagnose majority fetal congenital heart diseases, especially abnormality in four chamber view, but it is difficult to show the origination, branch or trend of the aorta. Transabdominal echocardiography is an important method in the early diagnosis of fetal congenital heart diseases.