Purpose or Case Report: Prenatal screening and diagnosis of fetal anomalies rely upon ultrasound studies (US). US is generally considered safe during pregnancy. It is estimated that 1% of all neonates are born with a congenital heart defect that makes careful standardized examination of the fetal heart a mandatory step during all fetal US exams. US examination of the fetal heart requires at least analysis of the fetal situs, the four-chamber (4CH) view and the three-vessel view (3V). In the evaluation of the fetal heart, it is now worldwide accepted that the three-vessel trachea (3VT) view should be obtained, if technically feasible, in supplement of the other classical fetal cardiac views (4CH, 3V).

The relevance of adding the 3VT view is that some congenital cardiovascular abnormalities, potentially significant for fetal outcome, can only be diagnosed with this view; these malformations include vascular rings and right aortic arches.
Methods & Materials: We conducted a retrospective review of prenatal US and cardiac US data of fetuses with abnormal 3VT view, with correlation with postnatal imaging (CTA) and outcome. The most frequent abnormalities detectable will be illustrated and discussed: right aortic arch with retroesophageal diverticulum of Kommerell, mirror-image right aortic arch, right aortic arch with aberrant left subclavian artery, right circumflex aorta, double aortic arch and left aortic arch with aberrant right subclavian artery.

The goals of this exhibit are:

- To review the normal appearance of the fetal 3VT view;
- To review the embryological development of aortic arches explaining the malformations that can be observed;
- To understand the significance of abnormal appearance of the fetal 3VT view by correlation with postnatal CT-scan imaging;
- To propose a practical algorithm and work-up regarding detection of an abnormal 3VT view in a foetus;
- To help radiologists provide appropriate counselling to parents when discovering an abnormal 3VT view in routine fetal screening.
Results:
Conclusions: