Figure 3. A 46-year-old female patient with Crohn's disease presenting with acute right flank pain. (a) MR urogram shows a level of obstruction at the mid/distal third of the right ureter, and axial CT confirmed a distal ureteric calculus. (b) Retrograde pyelography demonstrates a calculus (arrow) above a distal ureteric stricture, and removed at ureteroscopy.