Fetal echocardiographic diagnosis of isolated ductus arteriosus aneurysm: a longitudinal study from 32 weeks of gestation to term.

OBJECTIVE: To investigate the echocardiographic characteristics of isolated fetal ductus arteriosus aneurysm (DAA) and the factors influencing its development. METHODS: Fetal echocardiograms for 509 low-risk singleton pregnancies were performed longitudinally from 32 weeks of gestation. The ventricular outflow tracts and great vessels were visualized, focusing on changes in the ductus arteriosus (DA), and fetuses with DAA or ductus arteriosus dilatation (DAD) were identified. Prenatal and perinatal findings were compared between those infants diagnosed postnatally with and those without neonatal DAA. RESULTS: Forty-one of the 509 fetuses (8.1%) studied had neonatal DAA; 2.2% (11/509) had DAA and 5.9% (30/509) DAD before delivery. The mean gestational age at the time of diagnosis of fetal DAA/DAD was 36.9 +/- 1.7 weeks. The mean maximal internal diameter of DAA/DAD was 8.0 +/- 0.8 mm at initial diagnosis, increasing to 10.8 +/- 1.6 mm before delivery. All cases originated from the aortic end of the DA. Compared with fetuses without neonatal DAA, the affected cases had a markedly more curved DA prior to diagnosis, and higher peak velocities at the aortic end of the DA (P < 0.05). Newborns with fetal DAA/DAD had a larger placental weight to birth body weight (BBW) ratio and were less likely to have a BBW appropriate for gestational age (P < 0.05). All cases of fetal DAA/DAD regressed spontaneously. CONCLUSION: Isolated neonatal DAA is a continuity of fetal DAA/DAD. The development of fetal DAA/DAD is likely to be related to the higher peak velocities in the more markedly curved DA occurring in the latter part of the third trimester. Fetal DAA/DAD usually initiates at the aortic end of the DA, followed by progression towards the pulmonary end.