Role of routine fetal echocardiography in clinical practice: its impact on prenatal diagnosis of congenital heart disease in low risk population

Abstract

Purpose: Congenital heart disease occurs in approximately 8 of 1000 live births. Its prenatal diagnosis is important for proper perinatal and neonatal management. Basing referral for fetal echocardiography on presence of risk factors, excludes about 85% of fetuses with severe detectable heart defects from screening. The present study aims to examine the non‐selected low risk population to determine the diagnostic accuracy of fetal echocardiography in detecting cardiac anomalies.Methods: We included 39 808 low risk pregnant women who received antenatal care at the National University Hospital, Singapore between January 1986 and December 1994 and underwent routine second trimester ultrasound imaging to exclude fetal anomalies at the Antenatal Diagnostic Center. Ultrasonographers trained to do congenital abnormality scan including echocardiography (level IV scanning), performed examinations that was checked by obstetricians specially trained in obstetric ultrasonography. The duration of each scan was approximately 30 min. Equipment used were Hitachi 40,400,565A, Alokha 650 and Acuson 128XP. All subjects were followed to delivery. Postnatally, the neonates were examined by a neonatalogist for the confirmation of presence or absence of congenital anomalies. Patients who elected to terminate their pregnancies had their fetuses sent for postmortem assessment.Results: A total of 294 cases of congenital heart defects were identified prenatally by fetal echocardiography. Atrial and ventricular septal defects were the commonest anomalies identified (154), followed by left hypoplastic heart (23). In 36 subjects, abnormal cardiac sonographic findings were not confirmed postnatally on examination. On the other hand, there were 44 cases of cardiovascular anomalies that were missed by ultrasound prenatally. We obtained sensitivity of 85.4% for detection of congenital heart disease and a specificity of 99.9% to rule out any such anomalies. Our positive predictive rate was 87.7% and a negative predictive rate was 99.9%.Conclusion: We recommend routine screening by fetal echocardiography of all pregnancies for prenatal detection of cardiac anomalies, to increase the sensitivity and cost‐effectiveness of antenatal obstetric ultrasound screening and hence, to improve the perinatal management of cardiac anomalies.