Fig. 1.

Simple cyst (A): US shows a mass which appears well-circumscribed, with anechoic contents, thin echogenic exterior capsule, enhanced through-transmission, subtle acoustic shadowing at the edges. Complicated cyst (B): US shows that the content is not purely anechoic (like a simple cyst), but there are diffused echoes of low amplitude. Complex cyst (C): US shows a well-circumscribed anechoic mass containing solid components. Cysts with sediment (D): US shows an anechoic mass with sharp margins and posterior hyperechoic sediment.