Changes

With ultrasonography, larger stones (>5–7 mm) within the kidney, i.e., in the calyces, the pelvis and the pyeloureteric junction, can be differentiated, especially in the cases with accompanying hydronephrosis (Figure 1 and Figure 2). Hyperechoic stones are seen with accompanying posterior shadowing. Additional twinkling artifacts below the stone can often be seen using Doppler US. 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 renal stone located at the pyeloureteric junction.jpg|Figure 1. Renal stone located at the pyeloureteric junction with accompanying hydronephrosis.<ref name="Hansen2015" />File:Ultrasonography of centrally-located stone with posterior shadowing.jpg|Figure 2. Centrally-located stone with posterior shadowing. No hydronephrosis is present. Measurement of kidney length on the US image is illustrated by ‘+’ and a dashed line.<ref name=Hansen2015/></gallery> [[File:Ultrasonography of staghorn calculi filling the entire collecting system.jpg|Figure 3. thumb|Staghorn calculi filling the entire collecting system and creating pronounced shadowing.<ref name=Hansen2015/>]]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.). <gallery>