Complete Title: The added value of screening fetal echocardiography after normal cardiac views on a detailed ultrasound.

Objective Evaluate fetal echocardiography's ability to detect critical (lesions requiring immediate neonatal intensive care) congenital heart disease (CHD) after normal anatomic cardiac views on detailed ultrasound. Methods Singletons with both a detailed ultrasound at 18 + 0 to 22 + 6 weeks and echocardiogram performed at least 14 days later and at 20 + 0 to 24 + 6 weeks. Cases with cardiac pathology on detailed ultrasound were excluded. Different combinations of cardiac views were described: Basic (four-chamber, outflow tracts), Expanded (plus three-vessel view), and Complete (plus ductal/aortic arches). "Normal" was defined on either 2D gray scale or color Doppler. Primary outcome was rates of critical CHD missed on ultrasound but seen on fetal echocardiogram. Results One thousand two hundred twenty-three women had normal Basic cardiac views. One thousand one hundred ninety (97.3%) were confirmed normal on echocardiogram. Twenty-one (1.71%) total CHDs were missed, and three were critical (0.25%; 95% CI, 0.03%-0.53%). Of the 1,223 women, 763 had Complete views. Ten (1.31%) total CHDs were missed and one (0.13%; 95% CI, 0.13%-0.36%) was confirmed critical. Conclusion Fetal echocardiography can increase CHD detection despite normal cardiac anatomy on detailed ultrasound; however, CHDs missed are rarely critical. Approximately 750 fetal echocardiograms need to be performed to detect one critical CHD with Complete normal cardiac views on detailed ultrasound.