Figure 4.

Patient has a left percutaneous internal/external nephroureteral (PCNU) stent that is to be changed to a double-J stent. (A) A contrast study shows ureteropelvic junction obstruction. (B) A catheter has been successfully manipulated down the ureter into the urinary bladder. The catheter position is confirmed by contrast injection. (C) Final image after a double-J stent insertion showing a proximal loop formed within the renal pelvis. The small arrow indicates a tractogram that clearly identifies a well-formed tract between the kidney and the skin. (D) The distal loop is adequately formed within the urinary bladder.