Parenchymal reflux in renal dysplasia.

Primitive ducts, tubules, and cysts often communicate with the pelvoccalyceal systems of dysplastic kidneys, and may sometimes be filled in retrograde fashion with radiographic contrast material. Their size, shape, and distribution provide a variable radiographic appearance that must be distinguished from other causes of intrarenal reflux. When reflux filling of dysplastic structures is incomplete, the radiographic findings do not fully represent the severity of anatomic abnormality.