Early screening for fetal cardiac anomalies by transvaginal echocardiography in an unselected population: the role of operator experience.
OBJECTIVES: To examine the accuracy of early transvaginal fetal echocardiography performed in an unselected population by operators with different levels of experience and to compare the results with those obtained from a referral population. DESIGN: Prospective study. METHODS: A series of 4785 unselected fetuses and 221 referred fetuses were screened at 13-15 weeks' gestational age by transvaginal echocardiography. For each fetus, visualization of the four-chamber view plus the origin of the great arteries was attempted. Color Doppler imaging was only performed in cases of cardiac malformations already identified by two-dimensional echocardiography. The scans were performed by seven operators with different levels of experience. Reliability was assessed by conventional transabdominal echocardiography at 20-22 weeks, by postnatal follow-up in the first 3 months of life, and/or by autopsy in all cases of termination or fetal death. RESULTS: The rate of complete visualization (four-chamber view plus great arteries) was 47.5% in the unselected population, and 76.9% in the referral population. There were four (0.08%) true positives among the unselected fetuses, and five (2.3%) among referrals, mostly with enlarged nuchal translucency or other malformations. Among the unselected fetuses, nine false negatives were detected by transabdominal echocardiography. Improvement in the operators' ability to recognize cardiac anomalies in unselected population was disappointing and was influenced more by individual approach than by the number of examinations performed. CONCLUSIONS: Early screening for cardiac anomalies among unselected fetuses is ill-advisable. The usefulness of an early approach is confirmed in high risk fetuses or in the presence of enlarged nuchal translucency when performed by expert operators.