Objective: To examine the feasibility of diagnosing congenital cardiac defects between 11 and 14 weeks' gestation in a high-risk population.
Methods: Fetal echocardiography was first offered at 11 to 14 weeks' gestation to all patients at risk for congenital heart defects. Echocardiography performed at 11 to 14 weeks with normal results was repeated at 14 to 16 and 20 to 24 weeks. Final diagnoses of cardiac anomalies that had been observed at 11 to 14 weeks were established at 14 to 16 weeks or later Fetal echocardiography performed at 14 to 16 weeks with normal results was repeated at 20 to 24 weeks. Ascertainment of cardiac anomalies was obtained by postnatal echocardiography or pathologic examination of the fetal heart after termination of pregnancy. Most of the examinations were performed transvaginally until 16 weeks. The transabdominal approach was used at this stage only when patients refused the transvaginal examination or because of technical difficulties. Three hundred ninety-two fetal echocardiographic examinations were performed between 11 and 14 weeks' gestation; 438 examinations were performed between 14 and 16 weeks; and 777 examinations were performed between 20 and 24 weeks. The major indications for fetal echocardiography at 11 to 14 weeks were maternal diabetes and previous pregnancy with congenital heart defects.
Results: Six of 7 major fetal cardiac anomalies were detected. The only major cardiac anomaly that was not detected between 11 and 14 weeks was correctly diagnosed at 22 weeks. Only 1 of 5 minor fetal cardiac anomalies was detected between 11 and 14 weeks. Another 2 minor fetal cardiac anomalies were detected at 23 weeks. Four incorrect diagnoses of minor cardiac anomalies were excluded on repeated fetal echocardiography between 20 and 24 weeks.
Conclusions: The initial attempt to diagnose congenital heart defects should be offered at 11 to 14 weeks' gestation.