No renal calculus on the non-contrast study. Left hydronephrosis secondary to a high-grade PUJ obstruction with no excreted contrast seen in the left ureter and distal to the obstruction.
The left kidney is atrophic with cortical thinning, and its bipolar length measuring 10 cm compared to 13 cm on the right. Reduced parenchymal enhancement left kidney in keeping with poor function.
The single left renal artery arises from the posterior wall of the abdominal aorta. A small branch arises posteriorly coursing into the lower pole crossing the PUJ at the level of obstruction. The single left renal vein arises from the lower pole and drains into the IVC passing anterior to the aorta.
Incidental bifid right ureters fuse at the level of the pelvic brim. Right kidney is normal. The bladder is unremarkable.