Introduction
Background
A ureterocele is a submucosal cystic dilation of the terminal segment of the ureter. A ureterocele may be classified most easily as intravesical, defined by its presence entirely within the bladder, or extravesical, defined by the permanent presence of some portion of the ureterocele at the bladder neck or urethra. Other classification systems for ureteroceles are based on the location of insertion of the ureter into the bladder (simple [orthotopic] and ectopic) or based on their association with a single or duplicated system. [Also see Ureterocele, in Urology.]According to their morphology, ureteroceles may be stenotic (obstructive ureteral orifice within the bladder), sphincteric (ureteral orifice at the bladder neck), or sphincteric stenotic (obstructive ureteral orifice at the bladder neck).1 In addition, they can also be cecoureteroceles (extension of the ureterocele past the bladder neck into the urethra).
Ureteroceles are most commonly found in association with complete ureteral duplication (80%),2 but they can also be seen at the terminus of a single system. The association of a fluid-filled structure within the bladder leading to an ectopic dilated ureter and a hydronephrotic upper pole of a kidney is the sine qua non of a ureterocele associated with a duplicated system. The function of the upper pole segment is variable, depending on the relative degree of obstruction caused by the ureterocele.
A ureterocele associated with the upper-pole moiety is located medially and inferiorly to the lower-pole ureter, inserting in a more superolateral location (Weigert-Meyer rule). Intravesical single-system ureteroceles are typically associated with good renal function (>80% with excretory function), whereas extravesical single-system ureteroceles are seen with poor renal function (<30% with excretory function), dysplastic kidneys, and bladder outlet obstruction.
Increasingly, ureteroceles are detected on antenatal sonograms. Initial findings often include hydronephrosis and a fluid-filled structure within the bladder. Antenatal findings must be correlated with results of postnatal studies, including ultrasonography, cystography, and functional studies. Vesicoureteral reflux is present in 50% of ipsilateral lower-pole moieties in duplex systems and present in 10-25% of contralateral moieties in single and duplex systems.
Pathophysiology
The true etiology of ureteroceles is not known. A common etiology is unlikely in simple and ectopic ureteroceles. Several postulated theories for the etiology of ureteroceles include the incomplete dissolution of the Chwalla membrane during development, altered development of the ureteral bud, inadequate muscularization, Schistosoma haematobium infection, and trauma.
Histologically, ureteroceles contain abnormal musculature, with an incomplete patchy muscular coat. Electron microscopy shows a paucity of muscle bundles and smaller myocytes and an absence of thick myofibrils.
Clinically, ureteroceles are associated with obstructive uropathy.1 Detrusor hypertrophy is often seen if the ureterocele is associated with bladder outlet obstruction. Vesicoureteral reflux is present in 50% of ipsilateral moieties in duplex systems and 10-25% of contralateral moieties in single and duplex systems. Renal dysplasia is seen in 40% of resected duplex systems, with hydronephrotic atrophy and renal scarring also commonly seen.
Frequency
United States
The incidence varies from 1 case per 500 population to 1 case per 4000 population, based on autopsy reports.
International
Inadequate data are available regarding international populations.
Mortality/Morbidity
The morbidity of ureteroceles may be largely attributed to their ability to cause obstructive uropathy. The primary obstruction is at the level of the ureterovesical junction.1
Ipsilateral (50%) and contralateral (25%) vesicoureteral reflux is common. As a consequence, urinary tract infections are a common finding in infants with ureteroceles. Pyelonephritis and frank pustulant urosepsis may be present. Hydronephrosis is a common finding in both ipsilateral and contralateral renal units.
If left untreated, ureteroceles may progress to renal scarring or to renal failure if both kidneys are affected, with the subsequent need for dialysis and kidney allograft transplantation.
Prolapsed ureteroceles also may cause a functional bladder outlet obstruction.
Race
A predilection for ureteroceles is well documented in whites.
Sex
Females are affected more commonly than males, with a female-to-male ratio of 6:1. Interestingly, ectopic single-system ureteroceles are more common in males and are associated with additional congenital anomalies.3
Age
Two distinct groups of patients present with ureteroceles: (1) infants and children most commonly (60%) present with ectopic ureteroceles associated with a duplex system, with large ureteroceles commonly being seen in very young infants; and (2) adults are most likely to present with a simple single-system ureterocele.
Anatomy
- A ureterocele is a submucosal cystic dilation of the terminal segment of the ureter.
- Ureteroceles are most easily classified as intravesical, defined by their presence entirely within the bladder, or extravesical, defined by the permanent presence of a portion of the ureterocele at the bladder neck or urethra.
- Other classification systems for ureteroceles are based on the location of insertion of the ureter into the bladder (simple [orthotopic] and ectopic) or based on their association with a single or duplicated system.
- Ureteroceles may be stenotic (obstructive ureteral orifice within the bladder), sphincteric (ureteral orifice at the bladder neck), or sphincteric stenotic (obstructive ureteral orifice at the bladder neck). They may also be cecoureteroceles (extension of the ureterocele past the bladder neck into the urethra).
- Ureteroceles are most commonly found in association with complete ureteral duplication (80%),2 but they can also be seen at the terminus of a single system. The association of a fluid-filled structure within the bladder leading to an ectopic dilated ureter and a hydronephrotic upper pole of a kidney is the sine qua non of a ureterocele associated with a duplicated system. The function of the upper pole segment is variable, depending on the relative degree of obstruction caused by the ureterocele.
Presentation
The clinical presentation of ureteroceles is extremely variable, depending on the anatomic nature of the ureterocele. Increasingly, ureteroceles are detected on antenatal ultrasonography. The most common presentation of a ureterocele is a urinary tract infection with severe gram-negative sepsis in the first few months of life. Patients may present with hematuria, purulent urine, pyelonephritis, and abdominal pain. Urinary incontinence or retention may also be seen if the ureterocele causes an obstruction at the level of the bladder.
Ectopic drainage (outside of the trigone) in females may result in incontinence because the ureter drains beyond the bladder neck into the urethra, vagina, or uterus. However, incontinence is not seen in males because the ectopic ureter always inserts proximal to the external sphincter.
On physical examination, an abdominal mass representing the hydronephrotic kidney may be palpable. In girls, urethral prolapse may be apparent as a cystic mass in the urethral meatus. Rare instances of hemorrhagic infarction of prolapsed ureterocele and retrograde ejaculation have been reported.
Preferred Examination
Detailed history taking and physical examination should be performed in each patient with suspected or diagnosed ureterocele. The physician should assess for recurrent urinary tract infections, incontinence, abdominal mass, vulval masses, and symptoms of vesicoureteral reflux. In addition, females should undergo pelvic examination to identify vulval masses.
Radiologic evaluation of a ureterocele in an adult usually includes a kidney-bladder ultrasonography. Ultrasonography can be the initial study performed, and it can be used to detect prenatal ureteroceles. Ultrasonography noninvasively depicts anatomic changes in the kidney and bladder. Sonography should be performed with the bladder empty and with it filled to eliminate nonvisualization of ureteroceles due to either compression of the bladder or the ureterocele. Ultrasonography is the most sensitive test and often the only radiologic evaluation required for the diagnosis of ureteroceles.
Functional studies of the renal system include intravenous pyelography, CT scanning, and renal scanning. These contrast-enhanced studies help delineate the relevant renal anatomy, especially with regard to potential renal duplications. They are also useful in evaluating the differential renal function. Contrast-enhanced studies help identify ureteroceles within the bladder as a thin nonenhancing rim around contrast enhancement within the ureterocele. These functional studies often add supplemental information that is useful in the treatment of patients with ureteroceles, but they are typically not used as first-line imaging modalities for the diagnosis of suspected ureteroceles.
Limitations of Techniques
Ultrasonography is the most sensitive test for the detection of ureteroceles. Ultrasonography may cause ureteroceles to be missed if the patient's bladder is empty or fully distended, if the ureteroceles are small, or if the patient's body habitus precludes proper examination. Ultrasonographic findings are relatively specific for ureteroceles because the other etiologies of a cyst within a cyst are relatively rare.
CT scans, intravenous pyelograms, and renal scans are less sensitive for ureteroceles, but they help to more clearly delineate the functional anatomy of the kidneys.
For further discussion on the limitations of technique, see the sections below.
Differential Diagnoses
Bladder, Cystitis
Bladder, Trauma
Posterior Urethral Valve
Vesicoureteral Reflux
Other Problems to Be Considered
Hydronephrosis (any cause)
Pseudoureterocele (ectopic ureter)
Prolapsed ureter
Bladder diverticulum
Mesonephric duct cysts
Urethral polyps
More on Ureterocele |
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References
Merlini E, Lelli Chiesa P. Obstructive ureterocele-an ongoing challenge. World J Urol. Jun 2004;22(2):107-14. [Medline].
Belman AB, King LR, Kramer SA. Ureteral duplication anomalies: ectopic ureters and ureteroceles. Clin Pediatr Urol. 2002;677-735.
Schlussel RN, Retik AB. Anomalies of the ureter. In: Campbell's Urology. 1998;1814-59.
do Nascimento H, Hachul M, Macedo A Jr. Magnetic resonance in diagnosis of ureterocele. Int Braz J Urol. May-Jun 2003;29(3):248-50. [Medline].
Bader I, Akhter N, Anwar-ul-Haq, Choudhary A, Khan NU. Ectopic ureters misdiagnosed as ureterocele. J Coll Physicians Surg Pak. Jan 2004;14(1):50-2. [Medline].
Snow BW. Evolution of endoscopic management of ectopic ureterocele: a new approach. Int Braz J Urol. May-Jun 2007;33(3):452. [Medline].
Zougkas K, Kalafatis P, Ioannidis S, Katsikas V, Radopoulos D. Assessment of obstruction in adult ureterocele by means of color Doppler duplex sonography. Urol Int. 2005;75(3):239-46. [Medline].
Further Reading
Keywords
intravesical, extravesical, submucosal cystic dilation of the terminal segment of the ureter, simple ureteroceles, orthotopic ureteroceles, ectopic ureteroceles, stenotic ureteroceles, sphincteric stenotic ureteroceles, cecoureteroceles
