Stones can be found in all the areas listed, but the ureterovesical junction is the most common site of impaction because of its smaller diameter compared with the other 4 locations listed. For a stone to become impacted, it must have at least one diameter that is 2 mm or greater. Stones can also be impacted at the ureteropelvic junction, at the bifurcation of the iliac vessels, and over the pelvic brim.
