Changes

Large stones filling the entire collecting system are called coral stones or staghorn calculi and are easily visualized with US (Figure 3).

Stones in the ureters are usually not visualized with US due to the air-filled intestines obscuring the insonation window. However, ureteral stones near the ostium can be visualized with a scan position over the bladder. An exam of the ureteric orifices and the excretion of urine to the bladder can be performed by inspecting the ureteric jets in the bladder with color Doppler US (Figure 4.).

File:Ultrasonography of left hydroureter with ureteric jet.jpg|Figure 4. Left hydroureter with ureteric jet. No stone is visible. The red color in the color box represents motion towards the transducer as defined by the color bar.<ref name=Hansen2015/>