Are the collecting systems and ureters dilated in a duplicated system?
The appearance depends on whether there is reflux into the lower pole ureter and the exact site of the ectopically inserting upper pole ureter. In the typical situation, which is often bilateral, the distal ureters are contained within a common sheath and either come together or insert separately, but are close together in the trigone of the bladder. If the upper pole ureter is associated with a ureterocele (a localized dilation of the distal ureter), the ureterocele can protrude through the bladder to the urethra and manifests as a perineal mass. If a ureterocele is present, the upper pole of the kidney may be obstructed (leading to a “drooping lily” appearance of the lower pole collecting system due to inferolateral displacement caused by mass effect) or may be small and dysplastic, causing little or no effect on the lower pole. If a ureterocele is not present, the ureter from the upper pole moiety may insert in an ectopic location and have a stenotic insertion, causing obstruction (boys and girls), or may manifest with urinary dribbling or constant wetting (girls only) owing to an ectopic insertion into the urethra, vagina, or perineum.