ektope Uretermündung

Infant with a
diaper that is never dry. Sagittal US of the right kidney (above left) is normal while sagittal US of the left kidney (above right) shows a parenchymal bar between the upper and lower pole collecting systems. AP image of the bladder (below left) obtained during filling of the bladder during a voiding cystourethrogram (VCUG) shows right-sided vesicoureteral reflux into a dilated collecting system with the right ureter inserting normally into the base of the bladder. AP image of the bladder (below right) obtained during the voiding phase of the VCUG shows new left-sided grade I vesicoureteral reflux with the left ureter inserting into the urethra.The diagnosis was a left duplicated kidney with an ectopic insertion of the left ureter into the urethra and right Grade III vesicoureteral reflux.
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An ectopic ureter is a congenital renal anomaly that occurs as a result of abnormal caudal migration of the ureteral bud during its insertion to the urinary bladder. Normally the ureter drains via the internal ureteral orifice at the trigone of the urinary bladder.

In females, the most common sites for ureter insertion are the bladder neck and upper urethra (33%), vaginal vestibule between the urethra and introitus (33%), vagina (25%), and cervix and uterus (<5%) .

In males, the ureter may insert into the lower urinary bladder, posterior urethra, seminal vesicle, ductus deferens, ejaculatory duct, and rarely the rectum.

Epidemiology

The incidence of ectopic ureters is 1 in 1900, but may be higher because it is often underdiagnosed when asymptomatic, especially in males. It more common in females, F:M = 10:1.

Associations
  • may be solitary or a part of complex congenital anomalies, e.g. VACTERL
  • approximately 80% associated with duplex kidneys

Clinical presentation

Patients are symptomatic when the ureter inserts beyond the external urethral sphincter.

Pathology

Failure of separation of ureteral bud from Wolffian duct results in caudal ectopia.

In the case with complete duplication, it obeys the Weigert-Meyer rule - the ureter drains the upper moiety inserts more medial and more inferior to the lower moiety ureter and liable for obstruction while the lower moiety ureter is liable for reflux.

Patients are symptomatic when the ureter inserts beyond the external urethral sphincter.

Radiographic features

Intravenous urography (IVU)

It can detect abnormal ureteral insertion and associated anomalies e.g. renal duplication. In complete duplex kidney and ureter, the ectopic ureter usually drains the upper moiety and associated with ureterocele and obstruction.

Voiding cystourethrogram

Usually, the ectopic ureter is associated with vesicoureteric reflux, which can be detected and graded with VCUG.

Ultrasound

Associations and complications such as duplex kidneys, hydronephrosis and ureterocele can be also be assessed.

CT/MR urography

With the use of heavy T2 weighted imaging, the ureter and its insertion may be visualized.

MRI is also useful in the detection of other anomalies e.g. renal duplication, ureterocele and vertebral anomalies

Treatment and prognosis

The more distal the insertion, the worse the prognosis.

Differential diagnosis

Imaging differential considerations include:

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Assoziationen und Differentialdiagnosen zu ektope Uretermündung:
ektope
Ureterozele
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Reflux bei
ektoper Uretermündung
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