BACKGROUND: The aim of this study was to determine the feasibility of performing complete early fetal echocardiography (FE) at <17 weeks of gestation with comparison with standard FE in the midtrimester (17-23 weeks). METHODS: Fetal echocardiograms obtained in pregnancies studied at <17 weeks at the University of California, San Francisco, over a 5-year period were retrospectively reviewed. FE was considered complete if anatomic details could be assessed (systemic and pulmonary venous connections and atrial, ventricular, and septal [four-chamber sweeps], outflow and great artery, branch pulmonary artery, and arch anatomy) and if color and pulsed Doppler evaluations of the inferior vena cava, pulmonary veins, ventricular inflows and outflows, umbilical artery and vein, and ductus venosus were demonstrated. RESULTS: One hundred thirty-nine pregnancies were assessed by early FE at <17 weeks transabdominally during the study period (median gestational age, 14.0 weeks; range, 12-0/7-16-6/7 weeks). Additional transvaginal imaging was performed in 14 of 139 (10%) of early fetal echocardiographic studies. One hundred thirteen pregnancies were assessed using both early and later, standard (>17 weeks) FE. Of these, complete fetal echocardiograms were obtained in 27 early (24%; 95% confidence interval [CI], 17%-33%) and 76 later (67%; 95% CI, 58%-75%) exams. In most early exams, color and pulsed Doppler interrogation of the pulmonary veins was unsuccessful. If pulmonary vein Doppler assessment was excluded, complete studies were performed in 80 early exams (71%; 95% CI, 62%-78%) and 97 standard midtrimester exams (86%; 95% CI, 78%-91%). On early FE, heart disease was suspected in 20 pregnancies, and although no major congenital heart disease was missed, in four pregnancies, ventricular septal defects were found only on later FE or after birth. CONCLUSIONS: Early FE yields nearly complete information (exclusive of pulmonary venous interrogation) in the majority of patients.