INTRODUCTION — Ectopic ureter is diagnosed when the ureteral orifice is caudal to the normal insertion on the trigone of the bladder. In many instances, an ectopic ureter is not detected because the affected individual is asymptomatic. However, an ectopic ureter can produce symptoms, including urinary incontinence (only in females), urinary tract infection (UTI), or, rarely, urinary obstruction. Increasingly, ectopic ureter is detected on antenatal ultrasonography.
Ectopic ureter, including its pathophysiology, clinical presentation, diagnosis, evaluation, and management will be reviewed here. Other congenital anomalies of the kidney and urinary tract are discussed separately. (See "Overview of congenital anomalies of the kidney and urinary tract (CAKUT)" and "Evaluation of congenital anomalies of the kidney and urinary tract (CAKUT)".)
PATHOPHYSIOLOGY — An ectopic ureter forms when the origin of the ureteral bud from the mesonephric duct is abnormally high, and separation of the bud from the duct is delayed or does not occur (figure 1) . Ectopic ureters are commonly associated with a double (duplex) collecting system. In these cases, the double collecting system is thought to result from duplication of the ureteric bud. The cranial or superior ureteral bud is associated with the lower renal pole, and the caudal or inferior ureteral bud with the upper renal pole (figure 1 and picture 1). (See "Overview of congenital anomalies of the kidney and urinary tract (CAKUT)", section on 'Anomalies of the collecting system'.)
Ureteral orifice site — The ectopic orifice is always found along the pathway of the developing mesonephric system.
●Males – In males, the most common site is the posterior urethra, occurring in approximately 50 percent of cases . Other sites include the seminal vesicle, vas deferens, bladder neck, prostate to the level of the ejaculatory duct orifice, and epididymis (figure 2). The ectopic ureter in males is always above the external urinary sphincter. Therefore, males with an ectopic ureter do not have urinary incontinence.
●Females – In contrast, females with ectopic ureter that is not detected prenatally commonly present with urinary incontinence. This is because the ectopic ureters terminate at sites that bypass the urethral external sphincter. Since the upper pole kidney unit subtending the ectopic ureter is often dysplastic or poorly functioning, the amount of urine draining ectopically past the urinary sphincter is not voluminous. In addition, these patients void normally since the ipsilateral lower pole unit and the contralateral kidney drain normally into the bladder.
The following are the most common terminal sites of female ureteric ectopy, including their relative frequency  (figure 3).
•Bladder neck and upper urethra – 33 percent
•Vaginal vestibule between the urethra and vaginal opening – 33 percent (picture 2)
•Vagina – 25 percent (image 1)
•Cervix and uterus – Less than 5 percent
Only girls with a ureteral orifice site at or above the bladder neck and upper urethra will be continent.
Single versus duplex system — In published case series from the United States and Great Britain, the majority of ectopic ureters are associated with a duplex kidney, with rates that vary from 75 to 90 percent (figure 4) [1-3]. In these reports, ectopic ureters in duplex kidneys occur eight to nine times more frequently in girls than in boys.
In contrast, ectopic ureters associated with a single-kidney system appear to be more common in India and Japan [4-6]. In one study from India, 75 percent of the ectopic ureters were associated with a single-kidney system . In these case series, there was a strong female predominance. However, in reports from the United States and Great Britain, single-system ectopia is either equally or more likely to occur in males than in females [1,3,7,8]. It remains unknown why there is this geographical difference in the incidence of single-system ectopia and the sex variation . It may be related to genetic differences in the study population.
EPIDEMIOLOGY — The estimated prevalence of ectopic ureter based upon autopsy studies is approximately 5 per 10,000 individuals . The prevalence may be underestimated because many affected individuals remain asymptomatic. Ectopic ureters occur approximately six times more commonly in females than in males. Approximately 10 percent of ectopic ureters are bilateral.
Prenatal presentation — Ectopic ureter is increasingly being diagnosed by antenatal ultrasonography. In these cases, hydronephrosis is the usual presenting finding, most likely due to obstructed flow from narrowing of the ureter or bladder neck obstruction as the ectopic ureter passes through the muscle of the genitourinary diaphragm [3,8].
Postnatal presentation — Ectopic ureters present differently in toilet-trained males and females, primarily because in two-thirds of affected females, they bypass the external sphincter, resulting in incontinence, whereas the orifice of ectopic ureters in males is always proximal to the urinary sphincter.
Males — In males, an ectopic ureter usually is detected during an evaluation for anatomic abnormalities following a urinary tract infection (UTI). Rarely, if the ureter enters the genital ducts, patients may present with epididymoorchitis . Males do not present with incontinence because the ectopic ureter is always proximal to the external urethral sphincter (figure 2). (See 'Ureteral orifice site' above.)
Other presentations for boys with ectopic ureters include :
●Sense of urgency or frequency in patients with ureteric termination in the posterior urethra
●In rare cases, newborn males with bladder outlet obstruction due to a dilated prostatic ectopic ureter 
Females — UTI is also a common presentation of ectopic ureter in females, particularly among those who present in infancy. However, after toilet training, girls more commonly present with incontinence. This is because, in most cases, the site of insertion of the ectopic ureter is distal to or bypasses the external sphincter, usually ending in the vaginal vestibule or vagina (figure 3 and image 1). The incontinence is typically characterized by persistent spotting or moisture, requiring the use of a pad within their underwear. The parents/caregivers typically report that the girl has normal voiding habits, but is always wet. She may become wetter when she is sitting on the parent's lap because of urine pooling in the dilated ureter or vagina. Some patients are unaware that they have an abnormality, and think that the constant low-level moisture from the urinary incontinence is normal. (See 'Ureteral orifice site' above.)
Other presentations for girls with ectopic ureters include:
●Pyelonephritis, which tends to occur in older girls with a dysplastic kidney and dilated ectopic ureter. Infection results from urinary stasis and obstruction.
Genitourinary — The most common anomaly associated with an ectopic ureter is kidney hypoplasia or dysplasia in patients with a single collecting system, and hypoplasia/dysplasia of the affected pole of the kidney in patients with a duplex system . In one series, 25 of 33 ectopic ureters were associated with a poorly functioning or nonfunctional kidney moiety . The presence of a poorly functioning kidney moiety may impact the surgical decisions. (See 'Management' below.)
Other reported genitourinary anomalies include [2,4]:
●Hypospadias (see "Hypospadias: Pathogenesis, diagnosis, and evaluation")
●In patients with ectopy associated with duplex system, 80 percent of the contralateral system is also duplicated 
Nongenitourinary — Nongenitourinary anomalies in patients with ectopic ureters include [2,4]:
●Congenital cardiac lesions
●Conductive hearing loss
●Spinal cord defects including meningomyelocele
●Müllerian abnormalities including uterine didelphys and vaginal duplication
In particular, females with alleged unilateral kidney agenesis appear to be at risk for Müllerian abnormalities (eg, vaginal duplication with obstructed hemivagina). These abnormalities often present during puberty with an ectopic ureter from a minimally functioning hypoplastic kidney nubbin, which is associated with obstructed hemivagina [11,12]. This constellation of findings has been referred to as obstructed hemivagina and ipsilateral renal agenesis (OHVIRA) syndrome. However, cases from our center have demonstrated an ipsilateral dysplastic and atrophic kidney rather than renal agenesis, which was confirmed by the persistent excretion of dilute urine after resection of the obstructing vaginal septum (figure 5) . Atrophic kidneys may not be detected by a dimercaptosuccinic acid (DMSA) kidney scan and can also be difficult to localize on magnetic resonance imaging (MRI). As a result, increased clinical awareness of possible Müllerian abnormalities is needed in female patients with alleged renal agenesis .
DIAGNOSIS AND EVALUATION
Diagnostic tests — The diagnosis is made by imaging studies that identify the ectopic ureter.
Ultrasound of the kidneys and bladder is the initial diagnostic test (image 2 and image 1). The ureter is often dilated down to its abnormally low position. In many cases, the ureter may be followed proximally to a dysplastic or normal upper segment moiety of a duplex system. In single-system ectopia, the kidney may be dysplastic and difficult to visualize.
Computed tomography (CT) and magnetic resonance imaging (MRI) with contrast is helpful (image 1), especially in suspected cases of ectopic ureters and a normal ultrasound . For example, a nondilated ectopic ureter associated with the upper pole of a duplex system may not be visible on ultrasound. In this case, the only ultrasound finding may be a discrepancy in kidney length. In these patients, MRI and CT generally will pinpoint the location of the ureter, and confirm the diagnosis of a nondilated upper pole ureter draining ectopically.
Further evaluation — A voiding cystourethrogram (VCUG) should be performed when the diagnosis of an ectopic ureter is considered. We recommend the use of cyclic VCUG, which more reliably detects reflux into the ectopic ureter compared with a standard VCUG .
A renal scan is used to assess kidney function prior to surgery, as the function of the moiety associated with the ectopic ureter will impact surgical decisions. In patients with dysplastic kidneys that have little function, a static renal scan that uses the isotope dimercaptosuccinic acid (DMSA) (when available) may be more helpful than the dynamic scan that uses technetium-99m-mercaptoacetyltriglycine (Tc99mMAG3) for locating a poorly functioning ectopic kidney . In patients with hydronephrosis and/or dilated ureter, diuretic renography (renal scan and the administration of a diuretic) is performed to diagnose urinary obstruction. Diuretic renography is described in detail separately. (See "Evaluation of congenital anomalies of the kidney and urinary tract (CAKUT)", section on 'Dynamic renal scan' and "Evaluation of congenital anomalies of the kidney and urinary tract (CAKUT)", section on 'Static renal scan' and 'Management' below and "Fetal hydronephrosis: Postnatal management", section on 'Diuretic renography'.)
MANAGEMENT — Management consists of surgical reconstruction. The approach depends upon whether the system is duplex or single, and the extent of function of the involved kidney moiety.
Duplex system — Most cases of ectopic ureter in a duplex system are associated with a dysplastic upper pole kidney segment with minimal function (picture 3). Excision of this segment along with the ectopic ureter is usually curative.
Single system — In patients with an ectopic ureter in a single system, the affected kidney is usually small and poorly functional, and the base of the bladder (hemitrigone) is poorly developed. Management usually consists of nephrourecterectomy. If the kidney is functional, the treatment is resection of the distal ectopic ureter and reimplantation into the bladder.
OUTCOME — In children with ectopic ureters, long-term surgical outcome is excellent, with resolution of incontinence in almost all affected patients, and decreased rates of urinary tract infection (UTI) [2,4,8]. However, patients with either bladder outlet obstruction or bilateral single-system ectopic ureter may have voiding dysfunction and/or small bladders with inadequate capacity [8,17,18]. These patients are less likely to achieve continence. In some cases, bladder augmentation has been performed.
SUMMARY AND RECOMMENDATIONS
●Anatomy – Ectopic ureter refers to a ureteral orifice that is caudal to the normal insertion on the trigone of the bladder. The ectopic orifice is always found along the pathway of the developing mesonephric system. However, the anatomic site of the orifice and clinical presentation differ according to sex (see 'Ureteral orifice site' above and 'Postnatal presentation' above):
•Males – In males, the ectopic ureteral orifice is proximal to the external sphincter (figure 2). Therefore, incontinence is not seen in males.
•Females – In females, the ureteral orifice bypasses the external sphincter in two-thirds of the cases (figure 3 and picture 2). Therefore, incontinence is the predominant complaint in females.
●Associated kidney anomalies – Ectopic ureters are associated with both single and duplex (double) kidney collecting systems (picture 1). Kidney hypoplasia or dysplasia is a common finding in patients with a single collecting system, and hypoplasia/dysplasia of the affected pole of the kidney in patients with a duplex system. (See 'Single versus duplex system' above and 'Genitourinary' above.)
●Prevalence – Ectopic ureters are uncommon, occurring in approximately 5 per 10,000 individuals. They are six times more likely to occur in females than males. Approximately 10 percent are bilateral. (See 'Epidemiology' above.)
●Presentation – Increasingly, ectopic ureter is detected on antenatal ultrasonography. (See 'Prenatal presentation' above.)
For patients diagnosed postnatally, urinary tract infection (UTI) is the most common presenting sign for both sexes. After toilet training the presentation differs between males and females (see 'Clinical presentation' above):
•Males – In toilet-trained males, UTIs remain to be the most common finding, followed by flank pain, sense of urgency and/or frequency, and epididymoorchitis.
•Females – In toilet-trained females, the most common finding is urinary incontinence, which manifests as continuous wetness in a child with normal voiding habits.
•Ultrasound – The diagnosis of ectopic ureter is usually made by ultrasound (image 2). The characteristic finding is a ureter that is dilated down to its abnormally low position.
•Other tests – Other imaging studies can support the diagnosis and help guide surgical management. These may include (see 'Further evaluation' above):
-Computed tomography (CT) or magnetic resonance imaging (MRI) may be helpful (image 1), especially if the ultrasound is nondiagnostic (eg, if it shows only a discrepancy in kidney size without hydronephrosis). (See 'Diagnostic tests' above.)
-Voiding cystourethrogram (VCUG) can detect reflux. It should be performed when the diagnosis of ectopic ureter is considered.
-Renal scan is used to assess kidney function (particularly of the moiety associated with the ectopic ureter) prior to surgery
●Treatment – Ectopic ureters are managed surgically. The approach depends upon whether the renal system is duplex or single, and the extent of function of the involved kidney. (See 'Management' above.)
●Surgical outcome – Surgical outcome for ectopic ureter is excellent, with resolution of symptoms in most cases. (See 'Outcome' above.)
1 : Cooper CS, Snyder HM. The ureter. In: Adult and Pediatric Urology, 4th ed, Gillenwater JY, Grayhack JT, Howards SS, Mitchell ME (Eds), Lippincott Williams and Wilkins, Philadelphia 2002. p.2155.
9 : Epididymitis in infants and boys: underlying urogenital anomalies and efficacy of imaging modalities.
11 : [Simultaneous occurrence of an open Gartner-duct cyst, a homolateral aplasia of the kidney and a double uterus as a typical syndrome of abnormalities].
13 : Obstructed hemivagina and ipsilateral renal agenesis (OHVIRA) syndrome should be redefined as ipsilateral renal anomalies: cases of symptomatic atrophic and dysplastic kidney with ectopic ureter to obstructed hemivagina.
16 : The vagaries of proper imaging in diagnosing single-system ectopic ureter in children with continuous incontinence and outcomes of simple nephrectomy.
17 : Bilateral single ureteral ectopia: difficulty attaining continence using standard bladder neck repair.
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