Conventional radiologic studies with retrograde contrast administration via cystoscopically inserted ureteral catheters or anterograde through percutaneous nephrostomies, both performed under fluoroscopic control, provide the most precise delineation of the collecting system. However, diagnostic retrograde studies are performed rarely in obstruction, only when renal function is impaired and other imaging modalities are inconclusive, but mainly for selective urine sample collection in suspected tumor, and prior to URS and double‐J stent placement. Therapeutically inserted PNS can be used for anterograde urography.

 Colic, Acute, Renal