Presentation
Persistent agonizing left flank pain.
Patient Data



Mild left hydronephrosis due to an obstructing small left upper third ureteric stone measuring 6 mm.
Water attenuation fluid (10 - 15 HU) confined in the left perirenal space, more evident around its lower pole, is compatible with a rupture of a calyceal fornix in the kidney and urine extravasation / leak.
There is an additional lower calyceal stone measuring 12 mm.
Case Discussion
Obstructed left kidney with perinephric urinoma due to renal forniceal rupture from persistent increased pressure in the collecting system upstream from the obstructing ureteric stone.
Whilst contrast extravasation into a perinephric fluid collection in delayed excretory phases after IV contrast administration can confirm a forniceal rupture with urine leak, it may not be necessary if there is a classic appearance on a noncontrast study.