Ectopic Ureter
An ectopic ureter is one whose orifice lies outside the normal position at the trigone of the bladder. It arises from abnormal development of the ureteric bud, which separates late from the mesonephric duct, so that the ureter drains into a more caudal structure. Incidence is about 1 in 2,000 to 1 in 20,000.
80 percent are associated with a duplex collecting system. The ureter from the upper pole inserts ectopically, in accordance with the Weigert-Meyer rule: the upper pole ureter inserts inferior and medial to the lower pole ureter.
In females (female-to-male ratio of 6:1 in duplex systems), the ectopic orifice is in the:
- Urethra (33 percent).
- Vestibule (33 percent).
- Vagina (25 percent).
- Uterus and cervix (5 percent).
This produces continuous incontinence in spite of a normal voiding pattern.
In males, the ureter always inserts above the external urethral sphincter (bladder neck, posterior urethra, seminal vesicle, vas deferens or ejaculatory duct). Incontinence therefore does not occur, and presentation is by infection, epididymitis, and pain.
Single system ectopic ureters, in 20 percent, are usually associated with renal dysplasia or hypoplasia and are more often bilateral.
