Ultrasound demonstrates hyperechogenic foci with posterior acoustic shadowing consistent with renal calculi. The pyramids are diffusely echogenic, but without shadowing, suggestive of medullary nephrocalcinosis. Although nephrocalcinosis may eventually progress to involve most of the pyramid, acoustic shadowing is rarely seen even in this situation.

Acoustic shadowing may be appreciated only in rare cases of extreme involvement of the pyramids or if there is the development of associated calculi in the adjacent calices, like in this case.