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Ureterocele Last Updated: February 20, 2007 |
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| Synonyms and related keywords: ectopic ureterocele, orthotopic ureterocele, intravesical ureterocele, duplicated collecting system, cystitis, bladder outlet obstruction, stenotic ureterocele, sphincteric ureterocele, sphincterostenotic ureterocele, cecoureterocele, pathologic ureterocele, urinary tract infection, prolapsed ureter
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AUTHOR INFORMATION
| Section 1 of 11   |
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| Author: Eugene Minevich, MD, Assistant Professor, Department of Surgery, Division of Pediatric Urology, University of Cincinnati Coauthor(s): Leslie Tackett, MD, Fellow, Departments of Surgery and Pediatrics, Division of Pediatric Urology, Children's Hospital Medical Center at Cincinnati; Jong M Choe, MD, FACS †, Former Assistant Professor, Department of Surgery, Division of Urology, University of Cincinnati College of Medicine, Former Director of Continence and Urodynamic Center, Mount Vernon Urological Associates, LLC |
| Eugene Minevich, MD, is a member of the following medical societies:
American Academy of Pediatrics,
American College of Surgeons, and
American Urological Association |
| Editor(s): Michael Grasso, MD, Chairman, Department of Urology, Saint Vincent's Medical Center, Manhattan; Professor and Vice Chairman, Department of Urology, New York Medical College; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine;
Shlomo Raz, MD, Professor, Department of Surgery, Division of Urology, University of California at Los Angeles School of Medicine;
J Stuart Wolf, Jr, MD, FACS, David A Bloom Professor of Urology, Director, Division of Minimally Invasive Urology, Department of Urology, University of Michigan Medical Center;
and Stephen W Leslie, MD, FACS, Founder and Medical Director, Lorain Kidney Stone Research Center; Clinical Assistant Professor, Department of Urology, Medical College of Ohio; Chief Editor - eMedicine Urology |
Disclosure
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INTRODUCTION
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The ureterocele is one of the more challenging urologic anomalies facing pediatric and adult urologists today. It is a saccular out-pouching of the distal ureter into the urinary bladder. Ureteroceles pose a diagnostic and therapeutic dilemma because they manifest as a wide spectrum of anatomic abnormalities as well as perplexing clinical symptoms.
Ureteroceles arise from abnormal embryogenesis, with anomalous development of the intravesical ureter, the kidney, and the collecting system. Clinical signs and symptoms of ureteroceles range widely from recurrent cystitis to bladder outlet obstruction, but they can be asymptomatic, as well. 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. 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.
However, not all single-system ureteroceles assume an orthotopic position, and not all duplex collecting system ureteroceles position themselves 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.
Importantly, this classification does not have therapeutic relevance and is used infrequently. The characterization based upon the location of the orifice (intravesical vs ectopic) is more commonly used because it does have therapeutic implications, especially with respect to the likelihood of the development of vesicoureteral reflux following transurethral puncture of the ureterocele. 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 dilation 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 further 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. Clinical: Currently, most pediatric ureteroceles are found incidentally during routine screening antenatal ultrasound (US). Adult ureteroceles also are 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
- 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 often is 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 urinary tract infections (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 also has been reported to cause a bladder outlet obstruction in an adult male.
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 diagnosis of a prolapsing mass in children also should include urethral prolapse, sarcoma botryoides, and urethral caruncle. Prolapsing ureteroceles also can 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.
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INDICATIONS
| Section 3 of 11 |
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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
Urgent decompression with endoscopic incision, followed by a definitive bladder reconstruction, often is required in cases of urosepsis or severe azotemia. Indications for intervention in the pediatric and adult population are identical.
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RELEVANT ANATOMY AND CONTRAINDICATIONS
| Section 4 of 11 |
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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 also can 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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