Fetal diagnosis of interrupted aortic arch.

To determine the frequency of prenatal detection among liveborn patients with an interrupted aortic arch (IAA), the accuracy of prenatal diagnosis, and the anatomic features associated with IAA in the fetus. The prenatal diagnosis of an IAA is challenging. The data on the features and outcomes of fetal IAA are limited. This was a retrospective review of the fetuses and neonates diagnosed with IAA at the Children's Hospital Boston. From 1988 to 2009, 26 fetuses were diagnosed with an IAA. Of these, 21 were live born, and 5 pregnancies were terminated. Of these 21 patients, 18 were confirmed to have an IAA after birth and 3 had severe aortic coarctation. Of the 56 patients diagnosed with an IAA as neonates, 3 had a prenatal echocardiogram that did not include the correct diagnosis. Among the liveborn patients with a postnatally confirmed IAA, 24% were diagnosed prenatally, which increased from 11% during the first 7-year period to 43% more recently. Also, 15% of the prenatally diagnosed patients with IAA had a family history of structural or genetic anomalies. In fetuses with an IAA, echocardiographic Z-scores for the aortic valve and ascending aorta were significantly lower than in normal fetuses, but the left ventricular dimensions were normal. Aortopulmonary diameter ratios were abnormally low. In conclusion, although the identification of IAA on a prenatal echocardiogram can be challenging, a number of anatomic features can facilitate the diagnosis. In particular, a low aortopulmonary diameter ratio in the absence of a ventricular size discrepancy should prompt consideration of this diagnosis. Despite the diagnostic challenges, the frequency of prenatal diagnosis of the IAA is increasing.