Solution: Ureterocele

The CT flank pain examination shows a rounded filling defect within the bladder at the level of the right ureteral orifice. This is associated with a dilated right ureter and no discrete evidence on this examination for renal collecting system duplication. These findings are consistent with a "simple" or orthotopic ureterocele, which is a congenital prolapse of dilated distal ureter with its orifice into the bladder lumen at the usual location of the trigone. It can be an incidental finding, but can also be symptomatic due to obstructive symptoms. The classic finding is a "cobra-head" deformity of the distal ureter on contrast studies as you can see on these nephrostogram images from this patient.







An ectopic ureterocele is a ureteral bud arising in an abnormal location related to duplication of the collecting system the majority of the time. The insertion is distal to the trigone and usually affects the upper pole moiety of a duplicated kidney (Weigert-Meyer rule).