Ureterocele

INTRODUCTION — 

A ureterocele is a cystic dilatation of the terminal ureter either entirely within the bladder or extending into the urethra (figure 1). It may be noted as an incidental finding on antenatal ultrasonography, or it may be identified postnatally because of symptoms due to urinary tract infection (UTI) or obstruction.

The pathogenesis, clinical presentation, diagnosis, evaluation, and management of ureteroceles will be reviewed here. Other congenital abnormalities of the 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)".)

EPIDEMIOLOGY — 

The prevalence of ureteroceles based on autopsy studies is approximately 1 in 500 individuals [1]. Ureteroceles are more frequent in females than in males [2].

CLASSIFICATION

●Intravesicular versus ectopic – Ureteroceles can be classified based on location (figure 1):

•Intravesical – Ureterocele is entirely within the bladder

•Ectopic – A portion of the ureterocele extends beyond the bladder neck into the urethra

At times, differentiating between intravesical and ectopic ureteroceles may be difficult. Historically, ectopic ureteroceles that insert beyond the bladder neck into the urethra were called cecoureteroceles.

This classification system has been adopted by the Section on Urology of the American Academy of Pediatrics [3].

●Duplex versus single collecting system – Ureteroceles also may be classified depending on the collecting system:

•Duplex (double) collecting system – Approximately 80 percent of ureteroceles are associated with a duplex collecting system, with complete ureteral duplication. In such cases, the ureterocele is associated with the upper pole collecting system and 60 percent are ectopic [4]. (See "Overview of congenital anomalies of the kidney and urinary tract (CAKUT)", section on 'Duplication'.)

•Single collecting system (ie, single ureter and kidney) – Approximately 20 percent of ureteroceles are associated with a single collecting system. These ureteroceles are more likely to be intravesicular.

●Unilateral versus bilateral – Approximately 85 percent of ureteroceles are unilateral (equally distributed on right and left sides), and 15 percent are bilateral [5].

PATHOGENESIS — 

The underlying pathogenesis of ureterocele is unknown, and it appears that a single unifying theory does not explain how all of the different types of ureteroceles are formed [4]. In many cases, ureteroceles can be considered a diverticulum of the distal ureter within the bladder, caused by a stenotic ureteral orifice. The stenotic orifice may be related to abnormal ureteral insertion at the bladder level, similar to pseudoureteroceles and ectopic ureters, which are caused by similar mechanisms.

Embryologic mechanisms resulting in ureterocele formation may include [5]:

●Incomplete breakdown of the ureteral membrane between the ureteral bud and mesonephric duct, resulting in an obstruction that causes the formation of a ureterocele. This mechanism explains the formation of the majority of stenotic ureteroceles but not those with patulous ureteral orifices in the urethra.

●Obstruction of the ureteral orifice by the bladder neck because of developmental delay in the timing of the ureteral bud insertion into the bladder.

●Abnormal induction of the bladder trigone development that results in the absence of trigonal musculature in the intravesical portion of ureteroceles.

CLINICAL PRESENTATION

Antenatal — Many ureteroceles are detected incidentally on routine antenatal ultrasonography. Common findings are:

●Ureterocele – Seen as a cystic thin-walled mass within the bladder.

●Hydronephrosis – Since the ureterocele obstructs the distal end of the affected ureter, hydroureteronephrosis is a common finding in patients with ureteroceles (figure 1 and image 1) [6]. Indeed, approximately 2 percent of cases of antenatal hydronephrosis are caused by ureteroceles.

●Duplex collecting system – Approximately 70 percent of antenatally diagnosed cases of duplex systems with upper pole hydroureteronephrosis are associated with a ureterocele [7].

Postnatal

●Typical presentation – The most common postnatal presentation is during an evaluation for urinary tract infection (UTI) in the first few months after birth [4]. (See "Urinary tract infections in neonates".)

●Less common presentations – Uncommon postnatal presentations include:

•Males and females:

-Insidious symptoms including intermittent abdominal or pelvic pain, or poor growth [2]

-Palpable abdominal mass due to obstruction of the distal ureter by the ureterocele

-Bladder outlet obstruction (in patients with bilateral ureteroceles) [4]

-Hematuria

-Kidney stones (due to stasis and infection)

-Incidental finding during imaging for other conditions (more likely in males with a single-system intravesical ureterocele)

•Females:

-Vaginal mass due to prolapse of an ectopic ureterocele

-Urinary incontinence due to laxity of the external urinary sphincter

PRENATAL MANAGEMENT — 

In general, ureteroceles identified on prenatal ultrasound should be managed expectantly until birth.

Rarely, for selected fetuses with a severely obstructive ureterocele with oligohydramnios, in utero fetal intervention can be offered, consisting of decompression of the ureterocele. This is an experimental procedure and should only be conducted in research centers with clinical expertise in fetal intervention. The decision should be made collaboratively with the parent(s) with detailed discussion of the benefits and risks of fetal intervention versus expectant management.

In a small case series of fetuses with a severely obstructive ureterocele with oligohydramnios, in utero decompression of the ureterocele was performed under ultrasound guidance and/or fetoscopy at a mean gestational age of 21.6 weeks [8]. Eight of the 10 fetuses recovered normal amniotic fluid volume, and a liveborn child with normal kidney function was born at a mean gestational age of 37.6 weeks. However, two fetuses did not survive and underwent termination of pregnancy several weeks after the fetal intervention.

INITIAL POSTNATAL MANAGEMENT — 

Initial management of the neonate with an antenatally diagnosed ureterocele involves prophylactic antibiotics, ultrasound, and voiding cystourethrogram (VCUG) (algorithm 1):

Initiate prophylactic antibiotics — If a ureterocele is identified on prenatal ultrasound, antibiotic prophylaxis should be initiated at birth, usually with amoxicillin 10 to 15 mg/kg once daily. (See "Postnatal evaluation and management of hydronephrosis", section on 'Antibiotic prophylaxis'.)

The antibiotics are continued at least until the postnatal radiologic evaluation is performed, which consists of ultrasound to confirm the diagnosis and define anatomy and VCUG to determine whether there is associated vesicoureteral reflux (VUR). Antibiotic treatment is further continued if the VCUG reveals VUR and/or the ureterocele is associated with hydroureteronephrosis, indicating obstruction. For small ureteroceles associated with a single collecting system and without hydroureter or VUR, prophylactic antibiotics may be stopped.

Ultrasound — The diagnosis of ureterocele is made by ultrasonography.

●Timing – The timing of the postnatal ultrasound depends on whether there are concerns for lower urinary tract obstruction:

•If the prenatal ultrasound suggested possible lower urinary tract obstruction (bilateral hydronephrosis with bladder dilatation), the postnatal ultrasound should be performed within 48 hours of birth. This is because lower urinary tract obstruction requires immediate decompression to protect the kidneys and to avoid bladder outlet obstruction.

•If the prenatal ultrasound showed no evidence of lower urinary tract obstruction, the postnatal ultrasound is optimally performed after the third day of life and typically within the first week of life. This is because ultrasounds performed in the first 48 hours after birth may underestimate the degree of hydronephrosis due to postnatal fluid shifts. (See "Postnatal evaluation and management of hydronephrosis", section on 'Postnatal ultrasound'.)

●Findings – On ultrasound, the ureterocele is seen as a well-defined, thin-walled cystic mass in the base of the bladder (image 2). A dilated ureter also may be seen, especially behind the bladder. Ultrasonography also determines whether there is a single or duplex (double) collecting system (figure 2). In duplex systems, there is approximately an 80 percent chance that the contralateral side will also be duplex.

Differentiating an ectopic ureterocele from an intravesical ureterocele on ultrasound can be difficult. Ectopic ureteroceles are more likely in duplex systems. The ultimate distinction between an ectopic ureterocele and intravesical ureterocele is made at the time of cystoscopic inspection during planned endoscopic decompression.

Rarely, an ectopic ureter can mimic a ureterocele (a so-called pseudoureterocele), which requires different management [9]. Expert consultation with a pediatric urologist can make this distinction.

Voiding cystourethrogram — All patients with ureterocele should be evaluated by VCUG to identify whether VUR is present.

●Timing – The timing of VCUG depends on whether there are concerns for lower urinary tract obstruction:

•The VCUG should be performed shortly after birth if there is ultrasound evidence of lower urinary tract obstruction (bilateral hydronephrosis, bilateral ureteral dilation and/or dilated bladder, or thickened bladder wall).

•Otherwise, the VCUG is typically performed at two to four weeks of age, when the baby is already home, gaining weight, and bonding with the family.

●Findings – Because the contrast material used for VCUG may obscure the ureterocele itself, it is crucial to include early images, as the bladder is filling. In infants with duplex systems, VUR occurs in the ipsilateral lower pole in approximately 50 percent of patients and occurs on the contralateral side in 25 percent [4,10,11]. (See "Clinical presentation, diagnosis, and course of primary vesicoureteral reflux", section on 'Imaging'.)

SUBSEQUENT MANAGEMENT — 

The primary goals of ureterocele management are to prevent sepsis and recurrent urinary tract infections (UTIs), which can cause kidney scarring and impair kidney function, and to facilitate future reconstruction of the urinary tract [4].

Neonates and infants <1 year — Most neonates and infants <1 year of age with ureteroceles are managed with initial endoscopic decompression, followed by continued antibiotic prophylaxis and serial monitoring (algorithm 1). A minority will require definitive surgery, which is generally performed after one year of age.

Decompression versus expectant management

●Considerations – Many neonates and infants <1 year of age are managed with initial endoscopic decompression. The goal of decompression is to reduce the risk of sepsis or kidney damage due to recurrent infection. Decompression is generally performed rather than primary reconstruction because the latter is more challenging in small infants [1,12]. Decompression also facilitates future reconstructive surgery by decreasing the caliber of the dilated ureter. Furthermore, in approximately two-thirds of cases, the ureterocele resolves with the decompression so that a second surgery is not required [13]. Resolution is more likely in infants with single collecting systems compared with duplex systems and in those with intravesicular compared with ectopic ureteroceles. On the other hand, decompression can increase the risk of iatrogenic vesicoureteral reflux (VUR).

●Decisions by risk group – Based on the above considerations, the decision to perform decompression depends on the risk of recurrent infection and/or VUR, which varies with the underlying anatomy:

•High risk – Any of these:

-Sepsis

-Single collecting system with hydroureter

-Duplex system with hydroureter and ectopic ureterocele (movie 1)

-UTI with ureterocele and hydroureter

-VUR (ipsilateral lower pole VUR or contralateral VUR)

For infants with any of these high-risk characteristics, we suggest decompression via endoscopic puncture or incision (movie 2).

•Intermediate risk – Duplex system with hydroureter and intravesicular ureterocele; no history of UTI; with or without VUR.

For this group of infants, our practice is to perform initial endoscopic decompression for the reasons outlined above. However, some other experts manage conservatively, with prophylactic antibiotics and serial ultrasounds at least until toilet training is completed.

•Low risk – Single system with intravesicular ureterocele and no hydroureter; no history of UTI; no VUR.

For low-risk infants, expectant management is appropriate, consisting of prophylactic antibiotics and periodic reassessment with ultrasound every four months for the first year of life.

Renography — Renography (radionuclide scan, ideally with Tc-99m succimer [DMSA]) should be performed for all patients with duplex systems (which is 80 percent of those with ureterocele) and also for those with severe hydronephrosis or kidney size discrepancy. The procedure is performed at approximately four to six months of age. Renography measures function in the affected kidney segment. It also provides an index of impaired urinary drainage, which is seen as a delay in the isotope washout (especially after the administration of Lasix). (See "Radiologic assessment of kidney disease", section on 'Radionuclide studies'.)

The results inform decisions about surgical intervention. For example, in patients with a duplex system, the upper kidney segment that is associated with the affected ureter may contribute little or no function and may not be worth preserving; hence, an upper pole heminephroureterectomy is indicated [4]. In contrast, if the upper pole of a duplex system exhibits good function, definitive surgery consists of lower tract reconstruction.

Antibiotics and monitoring — Regardless of whether endoscopic decompression was performed, infants and young children with ureterocele require close monitoring during the first year of life or until definitive surgical correction. Management includes:

●Prophylactic antibiotics – Continue for at least the first year of life. For those with single collecting systems and no hydroureter, antibiotics can be discontinued at one year of age (or earlier) if there is no VUR. For those with mild or moderate VUR, antibiotics should be continued until definitive surgical correction or until toilet training is complete. An exception is infants with small single-system intravesicular ureteroceles and no hydronephrosis or VUR, who do not require prophylactic antibiotics.

●Serial ultrasounds – Perform serial kidney ultrasounds every four months for the first year of life to monitor for hydronephrosis and kidney size discrepancy.

●Reevaluation – At one year of age (or earlier if concerns arise), reevaluate with a voiding cystourethrogram (VCUG) and kidney ultrasound. Some centers would defer the VCUG if the patient is clinically doing well without infections.

Reconstructive surgery (if necessary) — Among infants who were initially managed with decompression, approximately one-third ultimately require definitive reconstructive surgery (see 'Outcomes' below) [13]. The timing and surgical approach depends on multiple variables, including the child's age, anatomy of the collecting system, presence of VUR (as assessed by VCUG and serial ultrasounds), and upper pole function (as determined by renogram) [5]:

●Duplex system – Management depends on the functioning of the upper pole, as determined by renography:

•Poorly functioning affected kidney segment – If the VCUG shows no significant associated lower pole VUR in a child with a poorly functioning upper pole kidney segment, a reasonable option is upper pole partial nephrectomy to remove the nonfunctional segment (picture 1). This is usually performed at six months to one year of age. The advantage of this approach is closure for the patient and family with one operation. Some urologists advocate an upper-to-lower-pole ureteric anastomosis in lieu of a partial nephrectomy. Another option is expectant management. As an example, expectant management with antibiotic prophylaxis was successful in a series of 14 children with duplex ureterocele, poor upper renal pole function, and no significant lower pole VUR [14]. Through follow-up to a median of eight years, none of the expectantly managed children required surgery, had a UTI, or became symptomatic.

If the VCUG shows grade 2 or higher reflux into the lower pole in a child with a poorly functioning upper pole kidney segment, decisions are more complicated. An upper pole heminephrectomy solves the upper pole issue but leaves the lower reflux to be dealt with. With lower grades of reflux, simultaneous endoscopic treatment is reasonable. With higher grades of reflux, one option is to reimplant the lower pole ureter, excise the ureterocele remnant, and reconstruct the bladder neck. Another approach is to reimplant the lower pole refluxing unit along with the upper pole nonfunctional obstructed unit and excise, with excision of the ureterocele [15].

•Well-functioning upper pole kidney segment – If the renogram shows good function of the associated upper pole kidney segment, definitive surgery is typically performed at one year of age. If there is no VUR, the procedure is a ureteroureterostomy (anastomosis of the upper ectopic ureter to the normal lower pole ureter at the level of the bladder). If there is persistent VUR in the lower pole segments, or new reflux into the punctured upper pole segment, the standard approach is bladder reconstruction with excision of the ureterocele and ureteral reimplantation.

●Single system – Management depends on the size of the ureterocele and the presence of VUR:

•For large ureteroceles and/or VUR, we excise the ureterocele and reimplant the ureter.

•Patients with single-system, small ureteroceles without ureteral dilation and without symptoms can be followed expectantly. We generally stop antibiotics at one year of age if there is no evidence of UTI. If the patient develops ureteral dilation and/or UTIs at any point, intervention may be warranted.

●Sepsis – Patients who present with sepsis secondary to obstruction at any age require immediate drainage of the kidney [16], which is typically performed by endoscopic incision (movie 2). Note the purulent material coming from the excised ureterocele. Endoscopic incision of the ureterocele often relieves the obstruction [17]. Percutaneous drainage of the kidney is rarely necessary.

Older children — Children who present when older than three to four years of age usually are managed with primary total surgical reconstruction similar to the procedures described above (see 'Reconstructive surgery (if necessary)' above). This approach avoids the need for endoscopic decompression with subsequent radiographic monitoring and the potential need for reoperation.

OUTCOMES — 

Overall outcomes for appropriately managed ureteroceles are very good. The course and outcomes are partly predicted by anatomy and kidney function.

●Need for definitive surgery after initial decompression – Among infants who undergo initial endoscopic decompression, between 30 and 40 percent require a second surgery [13]. In a 2024 meta-analysis (75 studies, 3022 patients), rates of reoperation were higher among studies performed before 2010 (40 percent) compared with after 2010 (33 percent), likely suggesting improved management strategies (patient selection and/or surgical techniques).

Patient characteristics that predict the need for reoperation include:

•Ectopic versus intravesicular ureterocele (54 versus 20 percent) [13].

•Duplex system versus single system (44 versus 18 percent) [13].

•Postnatal versus prenatal diagnosis (46 versus 20 percent) [18]. In addition, urinary tract infection (UTI) is more common in infants with postnatally diagnosed ureterocele, both before (84 versus 12 percent) and after surgery (27 versus 15 percent).

•Vesicoureteral reflux (VUR) identified prior to the initial decompression (primary VUR) versus no primary VUR [19].

Reasons for reoperation may include hydroureteronephrosis (insufficient decompression of the ureterocele) or ongoing or new VUR. The likelihood of reoperation increases with the number of kidney units involved with ureterocele (eg, upper pole only < upper and lower pole < bilateral) [20]. In a duplex system, the need for additional open surgery is usually related to the presence of lower pole reflux.

●Outcomes after bladder reconstruction – For patients who require bladder neck reconstruction with removal of a ureterocele, long-term outcomes are good. In a case series of 54 patients with an ectopic ureterocele who underwent total bladder reconstruction with excision of the ureterocele and ureteral reimplantation, long-term follow-up (median of 9.6 years) demonstrated good results, with urinary continence in almost all of the patients (n = 51) [21]. Subsequent endoscopic intervention was performed in 10 patients for persistent VUR and in seven patients for obstructive voiding. There were minimal lower tract complications, including infections.

SUMMARY AND RECOMMENDATIONS

●Definition – A ureterocele is a cystic dilatation of the terminal ureter either entirely within the bladder or extending into the urethra (figure 1). (See 'Introduction' above and 'Pathogenesis' above.)

●Prevalence – The estimated prevalence of ureteroceles is approximately 1 in 500 individuals. They occur more commonly in females than in males. (See 'Epidemiology' above.)

●Classification – Ureteroceles can be classified based on location (intravesical versus ectopic) and the associated collecting system (single versus duplex) (figure 1). Most ureteroceles are associated with a duplex collecting system. (See 'Classification' above.)

●Clinical presentation – Ureteroceles may present as an incidental finding on antenatal ultrasound, particularly if the ureterocele causes obstruction of the affected ureter (eg, upper pole ureter in a duplex system). Postnatally, ureteroceles are most commonly identified during an evaluation for urinary tract infection (UTI) in the first few months of life. Other less common presentations in older children include intermittent abdominal or pelvic pain, abdominal or vaginal mass, failure to thrive, urolithiasis, urinary incontinence, and, rarely, hematuria. (See 'Clinical presentation' above.)

●Diagnosis – The diagnosis of ureterocele is made by ultrasound. Further imaging with voiding cystourethrogram (VCUG) is used to determine if there is associated vesicoureteral reflux (VUR). In patients with duplex collecting systems, severe hydronephrosis, or kidney size discrepancy, renography is used to evaluate the function of all kidney segments (algorithm 1). (See 'Initial postnatal management' above and 'Renography' above.)

●Management

•Decompression – Initial management of neonates with a ureterocele depends on the anatomy and associated risks for sepsis, recurrent UTIs, and kidney function impairment (algorithm 1). For most neonates with a ureterocele, we suggest endoscopic decompression (Grade 2C) (movie 2). An exception is the small minority of patients with single-system, small ureteroceles without ureteral dilation and without symptoms or history of UTIs who can be followed expectantly. In either case, all of these infants require close follow-up with antibiotic prophylaxis and serial ultrasounds during the first year of life. (See 'Decompression versus expectant management' above.)

Patients with sepsis or urinary obstruction caused by the ureterocele require immediate drainage (typically with endoscopic incision).

•Prophylactic antibiotics – For most patients, we suggest prophylactic antibiotic therapy while awaiting definitive surgical intervention (Grade 2C). Antibiotic prophylaxis is continued in patients with ongoing VUR. Additional details regarding prophylactic antibiotics (including agents and dosing) are provided separately. (See "Management of vesicoureteral reflux", section on 'Antibiotic prophylaxis'.)

•Reconstructive surgery – Some patients may require complete surgical reconstruction, including approximately one-third of infants who were treated with initial endoscopic decompression. Decisions regarding choice and timing of surgical intervention are complex and depend on (see 'Reconstructive surgery (if necessary)' above):

-The presentation (postnatal presentation versus incidental finding on antenatal imaging)

-Location of the ureterocele (ectopic or intravesical)

-Type of collecting system (duplex versus single)

-Presence or absence of VUR

-Function of the associated upper pole kidney segment (in duplex systems)