Ectopic Ureterocele. images in left sagittal (A) and transverse (B) planes demonstrate an ectopic ureterocele (u) of the left upper pole ureter (lu) protruding into the lumen of the bladder base. The upper pole collecting system was hydronephrotic, but the lower pole collecting system was normal. The wall of the ureterocele (arrows) is clearly seen. A ureterocele changes in size with peristalsis of the ureter. B, bladder.