Beak sign (arterial dissection)

Last revised by Ammar Haouimi on 25 Jun 2020

The beak sign of arterial dissection is the acute angle formed at the edge of the false lumen in aortic dissection in axial cross-section. It is formed by the borders of the outer aortic wall and the intimal flap, and may be partially thrombosed (blunted beak). It is a reliable characteristic that helps in distinguishing from the true lumen.

The acute "beak" angulation represents the transverse limit of the dissection, where false lumen propagation is occurring along with a tear in the media.


The term bird's beak sign is used in a number of other contexts: see bird beak sign (disambiguation)

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Cases and figures

  • Figure 1: annotated image
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