eMedicine Specialties > Urology > Hydronephrosis and Ureter Disorders
Ureterocele
Updated: Jan 27, 2008
Introduction
Ureterocele is a saccular out-pouching of the distal ureter into the urinary bladder. It is one of the more challenging urologic anomalies that face pediatric and adult urologists. Ureteroceles pose a diagnostic and therapeutic dilemma because they manifest as a wide spectrum of anatomic abnormalities and can produce perplexing clinical symptoms.
Ureteroceles arise from abnormal embryogenesis, with anomalous development of the intravesical ureter, the kidney, and the collecting system. Ureteroceles may be asymptomatic or may cause a wide range of clinical signs and symptoms, from recurrent cystitis to bladder outlet obstruction. Because of the chronic obstructive nature of the ureterocele, the activity of the affected renal unit also ranges widely from a normal, well-functioning kidney to a nonfunctioning, dysplastic renal segment. However, with proper diagnosis and treatment, the outcome remains excellent.
For information on pediatric ureterocele, see the article Ureteral Duplication, Ureteral Ectopia, and Ureterocele in the Pediatric: General Medicine volume.Problem
A ureterocele is a congenital saccular dilatation of the terminal portion of the ureter. A ureterocele may be categorized based on its relationship with the renal unit or based on its distal ureteral configuration and location.
The following are the different types of ureteroceles classified by their association with the renal unit:
- Single-system ureteroceles are those associated with a single kidney, a single collecting system, and a solitary ureter.
- Duplex-system ureteroceles are associated with kidneys that have a completely duplicated collecting system and 2 ureters.
- Orthotopic ureterocele is a term used for a ureterocele whose orifice is located in a normal anatomic (orthotopic) position within the bladder. The orthotopic ureterocele usually arises from a single renal unit with one collecting system and is more common in adults.
- Ectopic ureterocele refers to those ureteroceles whose orifices are located in an ectopic position, such as the bladder neck or urethra. They typically arise from the upper pole moiety of a duplicated collecting system and are more common in the pediatric population.
Keep in mind that not all single-system ureteroceles assume an orthotopic position and that not all duplex collecting system ureteroceles are positioned in an ectopic location.
Another method of classifying ureterocele is based on its location and configuration. Thus, Stephens has proposed a classification based on the features of the affected ureteral orifice, as follows:
- Stenotic ureteroceles are defined as ureteroceles that are located inside the bladder with an obstructing orifice.
- Sphincteric ureterocele refers to those that lie distal to the internal sphincter. The ureterocele orifice may be normal or patulous, but the distal ureter leading to it becomes obstructed by the activity of the internal sphincter.
- Sphincterostenotic ureteroceles have characteristics of both stenotic and sphincteric ureteroceles.
- Cecoureteroceles are elongated beyond the ureterocele orifice by tunneling under the trigone and the urethra.
Frequency
Ureteroceles occur in approximately 1 in every 4000 children and occur most commonly in white persons. Females are affected 4-7 times more often than males. Although a slight left-sided preponderance appears to exist, approximately 10% of ureteroceles occur bilaterally. In the adult population, ureteroceles also occur more frequently in females, and 17-35% of ureteroceles occur in an orthotopic form.
In contrast to intravesical ureteroceles, the incidence of ectopic ureteroceles has been reported to be approximately 80% in most pediatric series. Similarly, approximately 80% of ureteroceles are associated with the upper pole moiety of a duplex system. When ectopic ureteroceles are associated with duplicated collecting systems, the upper pole moiety may be dysplastic or poorly functioning. Single-system ectopic ureteroceles are uncommon and are most often found in males.Etiology
The precise embryologic etiology of the ureterocele has been greatly debated. Several theories exist, including obstruction of the ureteral orifice, incomplete muscularization of the intramural ureter, and excessive dilatation of the intramural ureter during the development of the bladder and trigone.
The most commonly accepted theory behind ureterocele formation is the obstruction of the ureteral orifice during embryogenesis, with incomplete dissolution of the Chwalla membrane. (The Chwalla membrane is a primitive thin membrane that separates the ureteral bud from the developing urogenital sinus.) Failure of this membrane to completely perforate during development of the ureteral orifice is thought to explain the occurrence of a ureterocele.Pathophysiology
It is important to make a distinction between orthotopic and ectopic ureteroceles since therapeutic options and outcomes differ between these two clinical entities. The development of an ectopic ureterocele is best explained by reviewing the embryogenesis of the kidney and ureter.
Embryogenesis of the kidney and ureter
A ureteral bud, the primitive analog of the ureter, branches off the caudal portion of the Wolffian (mesonephric) duct during the first 4-6 weeks of gestation. The cranial portion of the ureteral bud joins with the metanephric blastema, a primitive analog of the kidney, and begins to induce nephron formation. The ureteral bud subsequently branches into the renal pelvis and the calyces and induces nephron formation. Caudally, the mesonephric duct and the ureteral bud are incorporated into the cloaca (urogenital sinus) as it forms the bladder trigone. At this point, the Chwalla membrane perforates to allow the formation of a normal ureteral orifice. If the membrane does not completely perforate, an orthotopic ureterocele results.
Importantly, alterations in the number of ureteral buds also result in ureteral anomalies. Before the mesonephric duct is absorbed into the urogenital sinus, it gives off a single ureteral bud. Complete ureteral duplication occurs when the mesonephric duct gives off a second ureteral bud. The ureteral bud closest to the urogenital sinus becomes the lower pole ureter, and the bud farther away becomes the upper pole ureter. As the common excretory duct is absorbed, the lower pole ureteral orifice migrates cephalad and laterally; however, the upper pole ureteral orifice migrates caudally and medially. This is known as the Meyer-Weigert law.
Because the lower pole ureteral bud is absorbed more rapidly, the detrusor submucosal tunnel becomes short. This short submucosal tunnel predisposes the lower pole ureter to reflux. In contrast, the upper pole ureteral bud is absorbed slowly, resulting in a long submucosal tunnel. At this point, the Chwalla membrane must perforate to allow the formation of a normal ureteral orifice. This results in an ectopic ureter. If the Chwalla membrane does not perforate completely, a ureterocele results, most likely in an ectopic location.Presentation
Currently, most pediatric ureteroceles are found incidentally during routine screening antenatal ultrasound. Adult ureteroceles are also found incidentally during imaging studies for urologic complaints of usually unrelated symptomatology. Ureteroceles are interesting radiologic curiosities that often do not have clinical sequelae in the adult population. However, when problems arise, presenting clinical symptoms of ureteroceles may include the following:
- Urinary tract infection (UTI)
- Urosepsis
- Obstructive voiding symptoms
- Urinary retention
- Failure to thrive
- Hematuria
- Cyclic abdominal pain
- Ureteral calculus
Pathologic ureteroceles most often affect the pediatric population. In young infants, failure to thrive may be the first sign of a symptomatic ureterocele. Complications of ureteroceles in both pediatric and adult populations occur because of the obstructive nature of the ureterocele and its anatomic location. Because of the distal ureteral obstruction, the ipsilateral renal moiety is often hydronephrotic or dysplastic. The degree of hydronephrosis may wax and wane depending on the amount of urine produced by the renal moiety. Cyclical expansion and decompression of the renal pelvis manifests as intermittent abdominal pain in older children and adults.
In the setting of untreated UTIs and hydronephrosis, affected older children and adults may reveal signs and symptoms of pyonephrosis and/or frank urosepsis. The dilated ureterocele may cause urinary stasis and is a risk factor for ureteral stone formation within its saccular cavity. When distal ureteral stones develop, they cannot pass spontaneously because of the obstructing ureterocele orifice. Presence of stones within a ureterocele is exclusive to the adult population. A prolapsing ureterocele in a female patient may cause physical obstruction of the bladder neck. Anatomic obstruction of the bladder neck by the cystic ureterocele may incite obstructive voiding symptoms or may precipitate acute urinary retention in both pediatric and adult populations. Intravesical ureterocele has also been reported to cause bladder outlet obstruction in an adult male.1
During the physical examination, particular attention should be paid to the abdomen and the genitalia. This is true for both pediatric and adult populations. Symptomatic ureteroceles with hydronephrosis manifest as signs of abdominal tenderness to palpation. An abdominal mass due to a large hydronephrotic kidney may be appreciated in the upper abdominal quadrant in thin adults and young children. Flank tenderness often accompanies the abdominal findings. In infants, an abdominal mass due to hydronephrosis may be noted by transillumination in a dark room.
During a female genital examination, a prolapsing cystic mass may be seen emerging from the external meatus in young girls or older women. This is a sign of a prolapsing ureterocele. However, the differential diagnoses of a prolapsing mass in children should also include urethral prolapse, sarcoma botryoides, and urethral caruncle. Prolapsing ureteroceles can also occur in boys, but they are much less common. Duplex systems are more likely to cause urethral obstruction in males, although they occasionally can occur with just a single system. A minority of ureteroceles are discovered incidentally during ureteral reimplantation for vesicoureteral reflux.
Indications
Treatment of the ureterocele is indicated to relieve obstruction and to preserve renal function. Indications for surgical intervention include the following:
- Recurrent UTI
- Urosepsis
- Ureteral calculi
- Intractable pain
- Renal compromise
Relevant Anatomy
Ureters are paired muscular tubes running from the renal pelvis to the bladder. They travel through retroperitoneal connective tissue in a serpentine fashion. In the adult, the ureter is approximately 30 cm long but varies with body habitus. The ureter is a urinary conduit composed of inner longitudinal smooth muscle fibers and an outer layer of circular and oblique smooth muscle cells. The inner and longitudinal muscle layers are enveloped by a thin layer of adventitia that contains an extensive plexus of ureteral blood vessels and lymphatics that course parallel to the ureter. In a normal state, urine is actively propelled from the renal pelvis down to the bladder via active contractions of the ureter.
The ureter receives numerous sources of blood supply as it courses down the bladder. The segment of the ureter from the renal pelvis to the common iliac artery is referred to as the abdominal ureter. The blood supply of the abdominal ureter includes the renal artery, the aorta, the gonadal artery, and the common iliac artery. The blood supply of the abdominal ureter enters medial to the ureter. The segment of the ureter from the common iliac artery to the urinary bladder is called the pelvic ureter. The blood supply of the pelvic ureter includes the internal iliac artery, vesical artery, uterine artery, and the middle rectal and vaginal arteries. The blood supply of the pelvic ureter enters laterally. The gonadal vessels run parallel to the ureter in the retroperitoneum until it courses obliquely from medial to lateral as it enters the pelvis.
The ureter can also be subdivided into upper, middle, and lower segments. The upper ureter courses from the renal pelvis to the upper border of the sacrum. The middle ureter runs from the upper sacrum to the lower sacrum, corresponding to the area of the common iliac artery. The lower ureter (pelvic ureter) extends from the lower border of the sacrum to the bladder.
During their course, the ureters encounter 3 natural areas of narrowing, as follows:
- Ureteropelvic junction
- Crossing of the iliac vessels
- Ureterovesical junction
The ureter is most narrow at the ureterovesical junction, followed by the ureteropelvic junction, and then at the crossing of the iliac vessels.
The ureterovesical junction may be divided into 3 sections, as follows:
- Terminal portion (juxtavesical ureter)
- Intramural portion
- Submucosal portion (lying under the mucosa of the bladder)
Contraindications
A contraindication for correction of a ureterocele is a small, asymptomatic ureterocele not causing any dilatation of the collecting system.
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References
Sekine H, Kojima S, Mine M, Yokokawa M. Intravesical ureterocele presenting bladder outlet obstruction in an adult male. Int J Urol. Jan 1996;3(1):74-6. [Medline].
Churchill BM, Sheldon CA, McLorie GA. The ectopic ureterocele: a proposed practical classification based on renal unit jeopardy. J Pediatr Surg. Apr 1992;27(4):497-500. [Medline].
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].
Coplen DE. Current Management of Ureteroceles. AUA Update Series. 1998;30.
DeFoor W, Minevich E, Tackett L, Yasar U, Wacksman J, Sheldon C. Ectopic ureterocele: clinical application of classification based on renal unit jeopardy. J Urol. Mar 2003;169(3):1092-4. [Medline].
Direnna T, Leonard MP. Watchful waiting for prenatally detected ureteroceles. J Urol. Apr 2006;175(4):1493-5; discussion 1495. [Medline].
Glassberg KI, Braren V, Duckett JW, et al. Suggested terminology for duplex systems, ectopic ureters and ureteroceles. J Urol. Dec 1984;132(6):1153-4. [Medline].
Gotta SF, Haillot O, Barat D, Lessourd B, Lanson Y. [Classification and treatment of ureteroceles in the adult]. Ann Urol (Paris). 1998;32(5):300-7. [Medline].
Husmann D. Ureteral Ectopy, Ureteroceles and Other Anomalies of the Distal Ureter. In: Gonzales ET, Bauer SB, eds. Pediatric Urology Practice. 1999:295.
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].
Mikuma N, Adachi H, Takatsuka K, et al. Ectopic ureterocele with a horseshoe kidney in an adult. Int J Urol. May 1996;3(3):243-4. [Medline].
Minoda K. [Ectopic ureterocele in a male adult: a case report]. Hinyokika Kiyo. Mar 1995;41(3):223-5. [Medline].
Nishimura H, Takeuchi T, Tahara H, Oshima K. Strangulated prolapsed ureterocele: a solid vulval mass in a woman. Int J Urol. May 1996;3(3):240-2. [Medline].
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].
Snyder HM, Johnston JH. Orthotopic ureteroceles in children. J Urol. Apr 1978;119(4):543-6. [Medline].
van den Hoek J, Montagne GJ, Newling DW. Bilateral intravesical duplex system ureteroceles with multiple calculi in an adult patient. Scand J Urol Nephrol. Jun 1995;29(2):223-4. [Medline].
Further Reading
Keywords
ureterocele, ectopic ureterocele, orthotopic ureterocele, intravesical ureterocele, duplicated collecting system, cystitis, bladder outlet obstruction, stenotic ureterocele, sphincteric ureterocele, sphincterostenotic ureterocele, cecoureterocele, pathologic ureterocele, single-system ureterocele, duplex-system ureterocele, urinary tract infection, prolapsed urete
