Screening for congenital heart disease prenatally. Results of a 2½‐year study in the South East Thames Region

OBJECTIVE: To assess the efficacy of four chamber view examination, during routine obstetric scanning, in the prenatal detection of fetuses with congenital heart disease. DESIGN: Prospective observational study. SETTING: Ten obstetric ultrasound units in the South East Thames Region. SUBJECTS: All pregnant women attending for routine obstetric ultrasound examination. INTERVENTION: Ultrasonographers performing routine ultrasound examinations were taught to obtain, and correctly interpret, the four chamber view of the fetal heart. When this view could not be achieved adequately, an attempt was made to identify a reason for failure and, if possible, to arrange a repeat scan. All suspected abnormalities were referred to a specialized unit. MAIN OUTCOME MEASURES: Numbers of true abnormalities detected or overlooked, and the number in whom abnormality was suspected incorrectly. RESULTS: Over a 2.5-year period, 69% of the known number of cardiac lesions associated with an abnormality of the four chamber view were detected prenatally during the routine obstetric scan, 10% were identified as a result of referal for other high-risk factors and 21% were overlooked. The overall positive predictive value in the 10 obstetric units was 36%. CONCLUSIONS: Prenatal screening for some forms of major congenital heart disease is possible by including examination of the four chamber view of the fetal heart in routine obstetric scans. However, there are important limiting factors that will influence the success of abnormality detection and must be taken into account if screening is to be effective nationwide.