Non-contrast CT scan shows left upper third ureteric stone measuring ~0.5 x 0.4 cm. This is associated with a dilated collecting system (grade II hydronephrosis) and proximal hydroureter down to the stone level with associated ureteric mural thickening and permeation of the periureteric fat.
The delayed scans showed extravasation of the excreted contrast around the left ureter creating a non-walled retroperitoneal collection with feathery irregularities along the ventral surface of the renal pelvis, with tracking of the contrast from the perirenal space, along the anterior border of left psoas muscle until it reaches the left side of the pelvis.