AUTHOR AND EDITOR INFORMATION

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INTRODUCTION

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Background

Ureteral abnormalities represent a complex and often confusing subset of urological anomalies that manifest in many ways. However, in the current era, hydronephrosis that is evident on fetal ultrasonography often heralds a ureteral abnormality.

Ureteral duplication is the most common renal abnormality, occurring in approximately 1% of the population and 10% of children who are diagnosed with urinary tract infections. Incomplete ureteral duplication, in which one common ureter enters the bladder, is rarely clinically significant. Alternatively, complete ureteral duplication, in which 2 ureters ipsilaterally enter the bladder, has a propensity for vesicoureteral reflux into the lower pole and obstruction of the upper pole, which can be problematic.

The upper pole ureter may be ectopic in its insertion into the bladder or may end in a ureterocele. Both conditions are more common in duplicated collecting systems but may also be seen in single systems.

A ureterocele is a cystic dilatation of the terminal intravesical ureter. Ureteroceles that are entirely contained within the bladder are considered intravesical. A ureterocele is considered ectopic if any portion is permanently situated at the bladder neck or the urethra, regardless of the position of the orifice.

A solitary collecting system is referred to as a single-system ureterocele. The orifice of a ureterocele may be stenotic, normal in size, or, occasionally, patulous. It may be located intravesically or extravesically. Ureteroceles widely vary in size, from ones that are difficult to visualize to ones that fill the entire bladder. Ureteroceles can often be obstructive if the orifice is stenotic or ectopically located and can also reflux if poorly supported with a gaping orifice.

Pathophysiology

Ureteral embryology is fundamental in understanding abnormal development of the ureter.

Ureteral development begins as early as 4 weeks' gestation. The ureteral bud branches off of the mesonephric (or Wolffian) duct and eventually extends into the nephrogenic blastema, an area of undifferentiated mesenchyma. The ureteral bud is responsible for the formation of the entire renal collecting system, from the ureteral orifice to the collecting ducts of the kidney. At the distal aspect of the ureteral bud, the mesonephric duct is incorporated into the developing bladder, and the ureteral orifice is superolaterally carried to its normal position on the trigone. The more distal segment of the mesonephric duct is carried inferomedially and is incorporated into the bladder neck. In the male fetus, it also develops into the seminal vesical, vas deferens, and epididymis. In females, it becomes the Gartner duct, which is located between the vagina and urethra.

In cases of urteral duplication where the ureteral bud arises twice, the lower pole ureter integrates with the bladder earlier than expected and, as a result, is carried into a more superolateral position. Thus, the distal ureter is poorly supported by the trigone and has a shorter intramural tunnel, both of which situations increase the likelihood of vesicoureteral reflux. The upper pole ureter then integrates with the bladder later than usual and is inferomedially carried. This may result in a ureteral orifice that is low on the trigone or is ectopically located at the bladder neck, ejaculatory duct, seminal vesical, or vas deferens in males.

In females, the ureter may end in a Gartner duct, which can eventually erode into the nearby vagina or the urethra, inferior to the urinary sphincter. This may be the cause of continuous urinary incontinence in females. In boys, all of the Wolffian structures are located above the external urinary sphincter, and incontinence does not occur.

Ureteral ectopia can occur without duplication and is believed to result from the delayed incorporation of the distal ureter into the developing bladder, as described above.

The embryology of the ureterocele is debatable. Some believe that failure of the Chwalla membrane to break down at the distal ureter during development results in obstruction and saccular dilation. Others argue that aberrant signaling from the expanding urogenital sinus results in dilation of the distal ureter.

Frequency

United States

In autopsy series, the incidence of ureteral duplication is estimated at slightly less than 1%. In studies of young children with urinary tract infections, the incidence of duplication rises to 8%. The incidence of ureteroceles has been reported to be between 1 per 5,000-12,000 population. Approximately 10% are bilateral, 60-80% are ectopic, and 80% are associated with an upper pole ureter of a duplex kidney. Single-system ectopic ureteroceles are rare, usually occur in males, and may be associated, in rare cases, with cardiac and genital anomalies. When ureteroceles arise from the upper pole of a duplicated kidney, the upper pole is frequently dysplastic.

Race

Ureteroceles are more common in whites than in blacks.

Sex

Ureteral duplication, ectopia, and ureteroceles are all more common in females. This may reflect the higher likelihood of urinary tract infections in females, resulting in subsequent detection of the duplication.

Age

Prenatally, ureteral duplication is commonly suggested by hydronephrosis when the upper pole ureter is associated with obstruction or when the lower pole is associated with high-grade reflux. The duplication may present in early childhood or later in life, when urinary tract infection prompts evaluation.

Prenatally, ureteral ectopia is commonly detected when hydronephrosis is present because of obstruction. Ectopic ureters that enter below the urethral sphincter present at school age or later in girls who have failed to toilet train or who have had continuous drip incontinence.

Prenatally, ureteroceles are most commonly diagnosed when associated with hydronephrosis or in childhood when associated with urinary tract infection. When found in adults, they are usually intravesical, are associated with a single collecting system, are less likely to alter the function of the involved kidney, and may not be of clinical concern.

CLINICAL

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History

Ureteral duplication and ectopic and nonectopic ureterocele tend to present early in life, even prenatally.

• Prenatal presentation: Prenatal maternal ultrasonography has led to earlier and increased detection of ureteral abnormalities. Hydronephrosis that is identified prenatally warrants postnatal follow-up imaging.
• Neonatal presentation: Urinary tract infection in the first few months of life remains the most common presentation. An infected obstructed system may lead to life-threatening urosepsis. Infants may also exhibit failure to thrive or nonspecific GI symptoms.
• Older childhood presentation
• • Urinary tract infection is a common presentation at any age. Ureteral duplication and ectopic ureters can be associated with both reflux and obstruction, predisposing to urinary tract infection. Hematuria or pain in the abdomen or flank may also occur.
  • Ureteral ectopia in females can present as continuous drip incontinence in cases in which the ureteral orifice is located in the vagina, septum, or the urethra, below the sphincter mechanism. Persistently damp underwear (day and night) is a typical history finding.
  • Girls can present with prolapse of the ureterocele through the urethra, which may lead to bladder outlet obstruction. This is the most common cause of urethral obstruction in girls. Ureteroceles may be seen upon careful physical examination of the genitalia.
  • Ureteroceles in boys may prolapse and occasionally obstruct the urethra, but this is very rare.

Physical

• A hydronephrotic kidney is the most common palpable abdominal mass in the newborn and suggests an obstructed kidney, possibly due to an ectopic ureter or ureterocele.
• Occasionally, urine that drips from the meatus of an ectopic ureter at the urethrovaginal septum can be detected. Close inspection of the genitalia in a female with urinary retention may reveal a prolapsing ureterocele.

DIFFERENTIALS

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WORKUP

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Lab Studies

• Rarely, bilateral renal dysplasia or significant renal scarring may be present, resulting in impaired renal function. In this scenario, renal function and electrolyte levels must be monitored. These patients must also be assessed for hypertension.

Imaging Studies

• Ultrasonography
• • Abdominal ultrasonography is the best initial screening study.
  • Renal measurements in duplicated collecting systems are often longer than those of a contralateral nonduplicated system.
  • Disparate hydronephrosis in the upper and lower pole of a kidney suggests ureteral duplication, especially with upper pole dilation associated with an obstructed or ectopic ureter or with a ureterocele.
  • A ureterocele can usually be seen at the bladder level and appears as a well-defined cystic intravesical mass that can be proximally followed into a dilated ureter. If the bladder is decompressed, visualization of a ureterocele is more difficult.
  • Ultrasonography provides imaging for gross evaluation of the renal parenchyma. Increased echogenicity and renal cysts are sonographic signs that suggest renal dysplasia.
• Intravenous urography
• • Intravenous pyelography (IVP) is not commonly used. IVP generally reveals duplicated collecting systems and their level of confluence. In young girls with persistent incontinence, IVP may be helpful in defining ureteral anatomy and the level at which an ectopic ureter may be found.
  • Typically, a ureterocele has been described as having a "cobra head" or " spring onion" configuration at the bladder level.
  • Stones that collect in the ureterocele may be visible on the scout film.
  • Because duplicated systems generally have poorly functioning renal moieties associated with ectopia or ureteroceles, these distinct images are usually observed with single-system intravesical ureteroceles. Delayed images are helpful in identifying poorly functioning renal units.
• Voiding cystourethrography
• • Duplicated collecting systems with lower pole reflux can be visualized using voiding cystourethrography (VCUG). The configuration of the kidney lacks opacification of the nonrefluxing upper pole, giving it the appearance of a "drooping lily."
  • Ectopic ureters generally do not reflux unless they are ectopic to the bladder neck. In this case, the refluxing unit opacifies only during voiding, when the bladder neck is open. Occasionally, the radiologist may inadvertently pass a catheter transurethrally up the ectopic ureter. The initial films then opacify only that collecting system and not the bladder.
  • Ureteroceles are best imaged at initial filling and appear as a filling defect in the bladder base. Identifying which side large ureteroceles are associated with can be difficult. Reflux of the ipsilateral lower pole is observed in approximately 50% of cases. Contralateral reflux may be observed in 25% of cases, and reflux into the ureterocele may be observed in 10% of cases.
• Renal scintigraphy
• • Mercaptotriglycylglycine (MAG-3) renal scintigraphy is the most commonly obtained renal scan used to evaluate relative renal function and drainage. It provides information on segmental renal function, allowing comparison of the upper pole moiety to the lower. It may aid in the determination of salvageability and selection of operative technique. MAG-3 Lasix renography may also quantitate the degree of obstruction in moieties with preserved function.
  • Technetium-99m (Tc99m) diethylenetriaminepentaacetic acid (DTPA) is similar to MAG-3 but is less efficacious in patients who have kidneys with poor function and in newborns because of their relatively impaired glomerular filtration rates. Radiation exposure is fairly high with this compound.
  • Tc99m dimercaptosuccinic acid (DMSA) is an agent that is taken up by the renal tubular cells and is used for renal scintigraphy.¹ DMSA resting can be used reliably to assess renal function but is not useful in evaluating urinary drainage of the upper urinary tract because it is secreted slowly into the urine.
• Axial Imaging
• • Axial imaging using CT scanning or MRI is rarely the initial study of choice.
  • Gadolinium-enhanced MRI may be valuable in opacifying an ectopic ureter that causes incontinence in a female, whereas other studies may not be diagnostic.
  • In one study, contrast CT scanning was the most reliable study in demonstrating the poorly functioning upper pole renal moiety and the associated ectopic ureter causing continuous drip incontinence.²

Procedures

• Although sometimes used as an investigative modality, cystoscopy is usually performed during surgical intervention to verify the diagnosis.
• The search for the orifice of an ectopic ureter may be extremely difficult. Tedious probing of any small dimple along the urethra or anterior vaginal wall with a whistle-tip catheter may be rewarded with visual confirmation of the offending moiety upon the retrograde injection of contrast. The use of indigo carmine or methylene blue injected intravenously may help in locating an ectopic ureteral orifice at the time of cystoscopy.
• Findings with large or ectopic ureteroceles, which can distort and obscure the entire field of vision, can be confusing. Finding the ureterocele orifice may be challenging.
• Small ureteroceles may not be evident, especially when the bladder is distended, which causes the ureterocele to flatten or evert. When associated with duplication, large ureteroceles may obscure visualization of any ipsilateral ureteral orifice.
• Retrograde pyelography can define the ureteral anatomy, and puncture of the ureterocele with instillation of contrast may aid in defining the origin of the lesion.

TREATMENT

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Medical Care

• Antibiotic suppression is usually warranted in newborns with hydronephrosis or in patients who present with urinary tract infection until the diagnosis is made and reflux is ruled out.
• For vesicoureteral reflux, antibiotics are generally continued until the reflux spontaneously resolves or is surgically treated or until the patient is toilet trained and has a considerable infection-free interval.
• Antibiotic prophylaxis is often continued in patients with obstructed systems and in infants with dilated nonobstructed systems.

Surgical Care

Various surgical options are available to treat ureteral duplication, especially with ureteral ectopia or ureterocele. The decision to surgically treat ureteral duplication requires the consideration of multiple elements, including the following:

• Age of patient
• • Duplicated collecting systems with reflux are expectantly managed with antibiotic suppression until the reflux spontaneously resolves or until the child is older (aged 6-12 mo) when surgery may be accomplished easier.
  • In infants, the small bladder can limit surgical reconstruction with regard to creating an adequately long ureteral tunnel to prevent recurrent reflux. Ureteral reimplants in small infants with breakthrough infections are possible but can be difficult and are associated with increased complications and failures.
  • In infants with duplicated systems and a well-functioning but obstructed upper pole moiety or an obstructed ectopic single-system ureter, urinary diversion may be the treatment of choice until the bladder is bigger and a ureteral reimplant with or without ureteral tailoring is more feasible.
  • A cutaneous ureterostomy allows for decompression of the system and may obviate the need for tailoring of the ureter at subsequent reimplant. However, it does commit the child to a second operation.
  • If the system is duplicated and no reflux is present in the lower pole system, a ureteroureterostomy is an attractive approach because it is a single-staged operation with relatively low risk.
  • Even in infancy, small instrumentation allows ureteroceles that are associated with good function to be endoscopically decompressed with incision. However, this carries the risk of subsequent reflux into that moiety. Incising a ureterocele that is associated with poor function provides little gain. The exception is an infant with urosepsis, but this may be best treated with percutaneous drainage and subsequent reconstruction, depending on the stability of the patient.
• Amount of functioning parenchyma: The upper pole system that serves a duplicated ureterocele typically makes up less than 30% of the unilateral renal function, and preservation of this function is usually not critical. If this poorly functioning moiety is not associated with reflux in other moieties, the best approach is often removal. Conversely, a poorly functioning renal unit that serves a decompressed ureterocele with no reflux has little or no indication for removal.
• Intravesical versus extravesical ureterocele: More than 90% of intravesical ureteroceles can be decompressed with endoscopic incision without the need for subsequent surgery for reflux. In endoscopic incision of extravesical ureteroceles, 50% of the cases require secondary surgery.³
• Detrusor backing: A poorly supported ureterocele that everts during voiding and becomes a bladder diverticulum may be more likely to require secondary reconstruction of the trigone than one that is well supported.
• Degree of ureteral dilation: If the ureter that is associated with ectopia or the ureterocele is massively dilated, attempts at reimplantation may be associated with a higher complication rate, such as obstruction and persistent reflux.
• Vesicoureteral reflux: Associated vesicoureteral reflux may be the single most important predictor of the need for open surgery. Reflux is the major factor that leads to the need for subsequent surgery after upper pole partial nephrectomy to decompress a ureterocele. If high-grade reflux is associated with a ureterocele, primary endoscopic incision decompresses the ureterocele and facilitates subsequent bladder-level surgery. If no reflux occurs, a simplified approach that consists of only an upper pole partial nephrectomy may be indicated.
• Number of renal moieties involved: Each ureter subtends a separate renal moiety. If only one moiety is involved and is poorly functioning, a single-stage nephrectomy or heminephrectomy is usually curative. The likelihood that this upper-tract approach will be curative diminishes as the number of other moieties involved with either reflux or obstruction increases. In this case, a lower-tract approach in which all problematic ureters can be simultaneously treated is a better option.
• Surgical approach
• • Endoscopic decompression: For intravesical ureteroceles associated with good renal function and associated with either a single or a duplex renal unit, a primary endoscopic approach may be used. A small incision low on the ureterocele is made, creating a flap valve to avoid reflux. Some series have reported that up to 90% of patients are adequately treated with endoscopic incision alone. A duplex renal system, ectopic ureterocele location, or preoperative reflux suggest trigonal anatomical distortion, increasing the likelihood of a secondary operation after puncture.⁴  
  • Open reconstruction at the bladder level (lower-tract approach): The ureter is reimplanted into the bladder with an adequate tunnel length to prevent reflux. Any obstructive elements can be excised; if the bladder base is attenuated, it can be reconstructed to provide the ureteral tunnel good detrusor backing. After tailoring, duplicated ureters can be tunneled in a common sheath or side-by-side, if indicated, or a ureteroureterostomy can be performed cephalad to the intramural tunnel. Although this approach may leave a poorly functioning or dysplastic renal moiety in place, this rarely causes a problem that requires reoperation in the absence of reflux or obstruction.
  • Open reconstruction at the renal level (upper-tract approach): When a ureterocele is associated with the upper pole of a duplex kidney, the upper pole often demonstrates poor function. Partial nephrectomy and partial ureterectomy may be performed. This approach is favorable if no reflux occurs because it potentially avoids bladder level surgery. This procedure is usually performed laparoscopically. This is also the procedure of choice for treating an incontinent girl with poorly functioning renal moiety that drains to an ectopic ureter.
  • Open reconstruction at the renal and bladder level (combined approach): Some authors still champion this approach, but the procedures require separate incisions and are associated with increased operative time and morbidity. When patients are carefully selected, an upper- or lower-end approach usually suffices and carries minimal risk of requiring further intervention.
  • Laparoscopic reconstruction: Laparoscopy is becoming more frequently used to perform ureteroureterostomy and ureteropyelostomy, in addition to more traditional uses such as partial nephrectomy where indicated ⁵.

Consultations

Early consultation, even prenatally, with a pediatric urologist is suggested in all cases.

MEDICATION

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Medication is not a component of care in this condition (see Treatment).

FOLLOW-UP

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Further Outpatient Care

• Postoperative radiographic imaging with ultrasonography and voiding cystourethrography (VCUG) is warranted to ensure the successful treatment of reflux and the absence of any obstructive element.
• Postoperative residual hydronephrosis that may persist for years, even in the absence of obstruction, is common. Imaging is usually repeated serially until the hydronephrosis resolves or stabilizes.
• Patients with renal scarring or dysplasia should be observed by their primary care physician with annual blood pressure assessment and urinalysis to rule out proteinuria.

Complications

• Short-term complications include urinary tract infection, hematuria, and, rarely, significant blood loss.
• Long-term complications include recurrence of reflux and, more rarely, ureteral obstruction.
• Heminephrectomy carries some risk of devascularization of the adjacent lower pole moiety, with loss of some or all of its function. Fortunately, this is uncommon.

Prognosis

• The ultimate prognosis of duplicated ureter, ureteral ectopia, or ureterocele is excellent.

MISCELLANEOUS

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Medical/Legal Pitfalls

• Surgical treatment of ureteroceles may require a staged approach. The family must be aware of the possible need for multiple surgeries.

Special Concerns

• Ectopic ureteroceles that involve the bladder neck carry a risk of injury to the urinary sphincter during repair, and incontinence must be discussed preoperatively with parents and patient.
• Patients with bilateral ureteral ectopia (a rare condition) that subtend single systems are at high risk for primary bladder dysfunction or maldevelopment, which warrants preoperative counseling.
• An ectopic ureter with a thin overlying bladder wall may be mistaken for a ureterocele. Endoscopic puncture in this setting creates a ureterovesical fistula. This can result in reflux or incontinence if the ureter ectopically ends below the urinary sphincter in females.

MULTIMEDIA

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Media file 1:  Ectopic ureter. Cystoscopic view of an ectopic ureter entering the bladder neck.
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Media type:  Photo

Media file 2:  Single-system ectopic ureter. A retrograde pyelogram of the ectopic ureter opacifies the dilated system. The ureter is obstructed when the sphincter is closed but opens to drain when the sphincter opens during voiding. Same patient pictured in Media file 1.
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Media type:  Radiograph

Media file 3:  Ectopic ureter to urethrovaginal septum. This patient presented with continuous drip incontinence. The blue catheter is positioned in the urethra. The gray catheter is positioned in the orifice of the ectopic ureter.
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Media type:  Photo

Media file 4:  Duplicated ectopic ureter to the urethrovaginal septum. Retrograde injection of contrast into the orthotopic lower pole (white arrow) ureteral orifice and ectopic upper pole (black arrow) orifice simultaneously opacifies both systems. Same patient pictured in Media file 3.
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Media type:  Radiograph

Media file 5:  A large ureterocele is seen as a filling defect on the early filling images of this cystogram.
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Media type:  Radiograph

Media file 6:  Bilateral single-system ureteroceles. The collecting systems and their associated ureteroceles are opacified on intravenous pyelography (IVP). Multiple stones in the ureteroceles may be discerned within the ureteroceles (white arrows) as filling defects.
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Media type:  Radiograph

Media file 7:  Bilateral ureteroceles with stones. This ultrasonogram at the bladder level depicts thin-walled, bilateral ureteroceles. Echogenic stone material can be seen in the left ureterocele. Same patient pictured in Media file 6.
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Media type:  Ultrasound

Media file 8:  Left duplicated kidney with upper pole ureterocele. This renal scan shows the typical findings of an upper pole duplicated system subtended by a ureterocele. The left upper pole (black arrow) shows minimal uptake when compared with the left lower pole or right kidney.
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Media type:  Radiograph

Media file 9:  Renal duplication. Marked upper pole hydronephrosis with minimal dilation of lower pole, indicative of a duplicated collecting system.
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Media type:  Radiograph

Media file 10:  Reflux into lower pole: A voiding cystourethrography (VCUG) that demonstrates reflux into the lower pole ureter with classic "drooping lily" configuration.
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Media type:  Radiograph

Media file 11:  Female infant with acute pyelonephritis. The ultrasonography findings are notable for left hydronephrosis.
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Media type:  Ultrasound

REFERENCES

Section 11 of 11

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1. Gill B. Ureteric ectopy in children. Br J Urol. 1980;52:257-63. [Medline].
2. Hanson GR, Gatti JM, Gittes KG. Diagnosis of ectopic ureter as a cause of urinary incontinence. J Ped Urol. February 2007;3(1):53-7.
3. Blyth B, Passerini-Glazel G, Camuffo C, et al. Endoscopic incision of ureteroceles: intravesical versus ectopic. J Urol. Mar 1993;149(3):556-9; discussion 560. [Medline].
4. Byun E, Merguerian PA. A meta-analysis of surgical practice patterns in the endoscopic management of ureteroceles. J Urol. Oct 2006;176(4 Pt 2):1871-7; discussion 1877. [Medline].
5. Lowe GJ, Canon SJ, Jayanthi VR. Laparoscopic reconstructive options for obstruction in children with duplex renal anomalies. BJU Int. Jan 2008;101(2):227-30. [Medline].
6. Caldamone AA, Snyder HM 3d, Duckett JW. Ureteroceles in children: followup of management with upper tract approach. J Urol. Jun 1984;131(6):1130-2. [Medline].
7. Coplen DE, Duckett JW. The modern approach to ureteroceles. J Urol. Jan 1995;153(1):166-71. [Medline].
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9. Gran CD, Kropp BP, Cheng EY, Kropp KA. Primary lower urinary tract reconstruction for nonfunctioning renal moieties associated with obstructing ureteroceles. J Urol. 2005;173:198-201. [Medline].
10. Husmann D, Strand B, Ewalt D, et al. Management of ectopic ureterocele associated with renal duplication: a comparison of partial nephrectomy and endoscopic decompression. J Urol. 1999;162:1406-9. [Medline].
11. Husmann DA, Ewalt DH, Glenski WJ, Bernier PA. Ureterocele associated with ureteral duplication and a nonfunctioning upper pole segment: management by partial nephroureterectomy alone. J Urol. Aug 1995;154(2 Pt 2):723-6. [Medline].
12. Johnson DK, Perlmutter AD. Single system ectopic ureteroceles with anomalies of the heart, testis and vas deferens. J Urol. Jan 1980;123(1):81-3. [Medline].
13. Klauber GT, Crawford DB. Prolapse of ectopic ureterocele and bladder trigone. Urology. Feb 1980;15(2):164-6. [Medline].
14. Malek RS, Kelalis PP, Burke EC, Stickler GB. Simple and ectopic ureterocele in infancy and childhood. Surg Gynecol Obstet. Apr 1972;134(4):611-6. [Medline].
15. Mandell J, Colodny AH, Lebowitz R, et al. Ureteroceles in infants and children. J Urol. Jun 1980;123(6):921-6. [Medline].
16. Siomou E, Papadopoulou F, Kollios KD, et al. Duplex collecting system diagnosed during the first 6 years of life after a first urinary tract infection: a study of 63 children. J Urol. 2006;175:678-81; discussion 681-2. [Medline].
17. Smith C, Gosalbez R, Parrott TS, et al. Transurethral puncture of ectopic ureteroceles in neonates and infants. J Urol. Dec 1994;152(6 Pt 1):2110-2. [Medline].

Article Last Updated: Sep 29, 2008