[The double aorta--rarity or artifact of ultrasound].

The double aorta is very rare. Only two cases are described in the literature. More frequent is a duplication artifact which is misinterpreted as being the image of a double aorta. This is caused by a refraction artifact which results from the difference in the velocity of sound between muscle tissue and fat tissue. Furthermore, a fat depot between parts of the rectus abdominis muscle has a prism-like effect. In most cases, this artifact can be avoided by lateral shifting of the transducer.