Abstract 15868: Title: Accuracy of Fetal Echocardiography in the Antenatal Diagnosis of Three Common Conotruncal Defects

Abstract

Introduction: The prenatal diagnosis of conotruncal defects (CTDs) has improved over the past decade, particularly with inclusion of outflow tract imaging at routine ultrasound. Appropriate prenatal counseling for CTDs demands an accurate diagnosis, as even more subtle cardiac pathology could complicate clinical outcomes. We sought to determine the anatomical accuracy of fetal echocardiography in evaluating common CTDs and factors that contribute to accuracy. Methods: All cases of tetralogy of Fallot(TOF), double outlet right ventricle(DORV) and truncus arteriosus(TA) encountered in our institution from 2007-2018 were reviewed. Discrepancies in anatomical findings between prenatal (most accurate exam) and postnatal (echo/surgery) or autopsy exams were categorized as: C1) no difference C2) minor difference with no impact on outcome (e.g.aberrant right subclavian artery), C3) minor difference that could make a minor difference to the delivery plan or surgery (e.g.branch pulmonary artery stenosis), C4) major difference that changes the course of the pregnancy, delivery or surgical planning (e.g.ductal dependency). Results: Of the 255 CTD cases, 162 had prenatal and postnatal and/or autopsy data available. Of the 162, 107(65.6%) fit C1, 35(21.5%) C2, 12(7.4%) C3, and 8(5.5%) C4. The greatest accuracy was observed in TOF, with 69/71(97.2%) in C1 and C2 versus 56/69(81.2%) in DORV and 16/22(72.7%) in TA(p=0.003). Excluding 5 cases at 10-16weeks, there was a tendency towards a greater proportion in C1 and C2 when examined at 17-23 weeks (60/64, 93.4%) versus 24-32 weeks (50/57, 87.7%) and >32 weeks (28/36, 77.8%) (p=0.06). Era of assessment also revealed a difference with 43/55(78.2%) of studies performed from 2007-2011 in C1 and C2 versus 99/107(92.5%) from 2012-2018 (p=0.01).When we compared pregnancies with one versus serial exams, we observed a lower proportion of C4 cases from 9.6% to 2.7%, respectively. In those with serial exams, 20% had achieved C1 or C2 only at serial exam. Conclusions: The diagnostic accuracy of fetal echocardiography in CTDs is generally high, especially for TOF and when performed at 17-24weeks. There has been significant improvement in accuracy since 2011. Serial exams potentially improve diagnostic accuracy.