Mickey Mouse sign (anencephaly)

Last revised by Reabal Najjar on 13 Nov 2022

The Mickey Mouse sign in obstetric ultrasound denotes the characteristic "floating appearance" of the fetal cerebral lobes due to the absence of the cranium due to anencephaly

Radiographic features

The sign is best seen in the coronal plane (in relation to the fetal head), where the cerebral lobes are seen floating in the amniotic fluid above the orbits (like the ears of the mouse). According to one study this sign was present in 5 out of 6 anencephalic fetuses diagnosed between 12-14 weeks of gestation 1,2

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Cases and figures

  • Case 1
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  • Case 2
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