Background: Cardiac abnormalities are frequently not detected by routine ultrasound screening examinations. Although detailed fetal echocardiography is more sensitive in detection of congenital heart disease, it is used only for high-risk cases. The main aim of this study was to assess the prenatal detection of congenital heart disease by detailed fetal echocardiography in an unselected, consecutive group of pregnant women.
Methods: Between Jan 1, 1993, and Sept 30, 1994, all women who attended our antenatal-care unit were routinely offered a detailed fetal echocardiography examination at 18-28 weeks' gestation. 3085 consecutive women were screened: 2181 were screening cases with no known risk factor for congenital heart disease; 540 had maternal risk factors for congenital heart disease, such as a family history or coexisting maternal disease; 364 had sonographically detected abnormalities. The examination included the four-chamber view, outflow-tract scan, and colour-flow mapping; doppler and M-mode investigations were also done when appropriate.
Findings: 46 cases of congenital heart disease were detected prenatally by echocardiography-15 in the group with no risk factors, three in the group with maternal risk factors, and 28 in the group with sonographic abnormalities. Postnatal assessments found six further cases of congenital heart disease that had not been detected prenatally, but these were all minor cases. There were no false-positive diagnoses (sensitivity 85.5%, specificity 100%). The incidence of congenital heart disease in screening cases with no risk factors and in those with maternal risk factors was low (6.9% per 1000, 5.6 per 1000) and similar to the expected overall incidence of 8.0 per 1000 livebirths in the general population. In the group with sonographic abnormalities congenital heart disease was found significantly more often (79.9 per 1000).
Interpretation: Inclusion of detailed fetal echocardiography as a screening examination has a substantial effect on detection of congenital heart disease since a major proportion of prenatally detectable cases occur in a low-risk population.