Snowstorm sign (complete hydatiform mole)

Snowstorm sign in obstetric imaging is classically seen in complete hydatiform mole. It is characterized by the presence of many hydropic villi which gives the ultrasonographic appearance of a central heterogeneous mass having a solid, hyperechoic area and interspersed with a multitude of cystic areas and filling the entire uterine cavity.

A similar sign has also been described in extracapsular breast implant ruptures.