Importance of "Guidelines for performing fetal cardiac scan" in prenatal screening for fetal congenital heart disease

Abstract

To investigate the application of "Guidelines for performing fetal cardiac scan", issued by the International Society of Ultrasound in Obstetrics and Gynecology in 2006, in prenatal screening of fetal congenital heart disease (CHD). Totally, 5000 singleton pregnancies presented at the Maternal-Fetal Medical Center of the Affiliated Drum Tower Hospital of Nanjing University Medical School from September 2006 to July 2007, for prenatal screening were included in this study, with the median maternal age of 28 (range, 18 approximately 48) and the median gestation of 27 (range, 18 approximately 40) weeks. Ultrasound screenings were performed on each fetal heart according to "Guidelines for performing fetal cardiac scan" via the four-chamber and outflow tracts & three-vessel views and fetal echocardiographies were further conducted for suspected cases. Once congenital heart disease was confirmed, amniocentesis or cordocentesis was suggested for fetal karyotyping for ongoing pregnancies and autopsy was performed when the pregnancy was terminated after formal consent. Born babies were followed up at 2 approximately 6 months of age using echocardiography. The four-chamber views were successfully obtained in 97.64% (4882/5000) of all the pregnancies, among which the left ventricular and right ventricular outflow tracts and three-vessel views were obtained in 87.69% (4281/4882), 82.51% (4028/4882) and 96.29% (4701/4882), respectively. Higher successful rate was found in the second trimester than the third trimester in obtaining the standard views (P < 0.05). Finally, 73 (1.50%) among the 4882 cases were diagnosed as CHD. Fifty of them were diagnosed prenatally (24 cases in the second trimester and 26 cases in the third trimester) and 23 were missed and 1 misdiagnosed by prenatal ultrasound. Eighteen cases were found with extracardiac malformations. Autopsy was performed in 19 CHD which diagnosed prenatally, and all autopsy reports were consistent with ultrasound foundings. Twelve babies received postnatal echocardiography among which 11 were unanimous, and 1 baby diagnosed as tricuspid insufficiency prenatally was confirmed normal after birth. Abnormal karyotype was found in 7 out of the 23 who had karyotyping performed. Altogether, 28 cases were diagnosed by four chamber view only and 50 cases by combining other views, giving the sensitivity, specificity, false negative rate and false positive rate of 69% (50/73), 99.98% (4808/4809), 0.48% (23/4831) and 2% (1/51), respectively. The "Guidelines for performing fetal cardiac scan" is practical and easy to abide by. The optimal time for fetal cardiac examination is at 18 approximately 27 weeks of gestation. Four-chamber view together with the outflow tracts and three-vessel views examination can detect 69% of CHD in utero.