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Key Points

  • Ectopic ureteroceles are associated with duplex collecting systems and are more common in females.

  • An ectopic ureterocele can be stenotic or refluxing.

  • Ectopic ureteocele can result in dysplastic changes in the superior pole of ipsilateral kidney.

  • Ectopic ureteroceles can be challenging to diagnose as they intermittently decompress.

  • Ectopic ureteroceles are a rare cause of bladder outlet obstruction.


A ureterocele is a cystic dilatation that occurs at the distal end of the ureter at its junction with the bladder. Simple ureteroceles are those that are located in the normal location of the ureteral orifice in the trigone of the bladder. Simple ureteroceles are more commonly detected in adults and usually are associated with a single collecting system. Simple ureteroceles are rarely associated with the upper pole ureter of a complete duplication of the collecting system. Simple ureteroceles may be associated with a varying degree of obstruction, but this is not significant in most patients. In contrast, with an ectopic ureterocele the ureteral orifice is located in an ectopic position, usually distal to the trigone, and this form is typically associated with a duplex collecting system. Ectopic ureterocele is also associated with an increased incidence of duplication in the contralateral kidney. The ureterocele may vary in size, from a tiny cystic lesion within the submucosal ureter, to that of a large cystic balloonlike structure that fills the bladder. The size of the ureterocele may fluctuate from one examination to the next. Histologically, the ureterocele is covered by the mucosa of the bladder and lined by the mucosa of the ureter, with varying degrees of attenuated smooth muscle bundles and connective tissue between the two layers of mucosa.

Several theories have been proposed to account for the embryonic development of a ureterocele. In one theory, a membrane covering the ureteral orifice persists for a long period, leading to the development of the ureterocele (Chwalle, 1927). In another theory, a ureterocele forms as a result of a stimulus to an expansion that transforms the bladder into a globular cap, creating an expanded thin-walled distal ureter (Stephens, 1971). Lastly, a localized embryonic arrest has been hypothesized as the cause of the ureterocele (Tokunaka et al., 1981).

Ectopic ureterocele has been classified anatomically by Stephens (1958, 1983). In this classification scheme, stenotic ectopic ureterocele is characterized by a small stenotic orifice and accounts for approximately 40% of cases. In sphincteric ectopic ureterocele, the orifice of the ureterocele is within the internal sphincter and accounts for an additional 40% of cases. In sphincteric ectopic ureterocele the ureteral orifice may be of normal caliber or may be enlarged and may open either in the posterior urethra in males or distal to the external sphincter in females. Sphincterostenotic ectopic ureterocele accounts for approximately 5% of cases. The stenotic orifice of this type of ectopic ...

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