You are in: eMedicine Specialties > Urology > Hydronephrosis and Ureter Disorders UreteroceleArticle Last Updated: Jan 27, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 13
  Author: Eugene Minevich, MD, Assistant Professor, Department of Surgery, Division of Pediatric Urology, University of Cincinnati Eugene Minevich is a member of the following medical societies: American Academy of Pediatrics, American College of Surgeons, and American Urological Association Coauthor(s): Leslie Tackett, MD, Fellow, Departments of Surgery and Pediatrics, Division of Pediatric Urology, Children's Hospital Medical Center at Cincinnati Editors: Michael Grasso, MD, Chairman, Department of Urology, Saint Vincent's Medical Center; 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; Stephen W Leslie, MD, FACS, Founder and Medical Director, Lorain Kidney Stone Research Center; Clinical Assistant Professor, Department of Urology, University of Toledo Author and Editor Disclosure Synonyms and related 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 INTRODUCTIONSection 2 of 13
  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.ProblemA 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:
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:
FrequencyUreteroceles 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.EtiologyThe 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.PathophysiologyIt 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.ClinicalCurrently, 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:
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. INDICATIONSSection 3 of 13
Treatment of the ureterocele is indicated to relieve obstruction and to preserve renal function. Indications for surgical intervention include the following:
RELEVANT ANATOMYSection 4 of 13
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:
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:
CONTRAINDICATIONSSection 5 of 13
A contraindication for correction of a ureterocele is a small, asymptomatic ureterocele not causing any dilatation of the collecting system. WORKUPSection 6 of 13
Lab Studies
Imaging Studies
Other Tests
Diagnostic Procedures
Histologic FindingsUsually, the walls of ureteroceles demonstrate loss of muscle and collagen. It appears that incomplete muscularization of the distal ureter may be responsible for expansion of the ureterocele out of proportion to the rest of the normal ureter. However, the walls of stenotic ureteroceles appear to have greater muscle composition than other types of ureteroceles. TREATMENTSection 7 of 13
Medical therapyObservation alone is rarely a good option in symptomatic ureteroceles. The physician must rapidly initiate aggressive antibiotic therapy. Antibiotics should be instituted during the initial diagnostic evaluation and during surgical intervention for both pediatric and adult ureteroceles. Surgical therapyIndications for surgical treatment for both pediatric and adult ureteroceles depend on the site of the ureterocele, the clinical situation, associated renal anomalies, and the size of the ureterocele. Goals of treatment include the following:
Surgical approach is selected based on the following:
Surgical therapy for both pediatric and adult ureteroceles may include endoscopic incision or transurethral unroofing of the ureterocele in the adult patient, upper pole heminephrectomy and partial ureterectomy with ureterocele decompression, ureteropyelostomy, excision of ureterocele and ureteral reimplantation, and nephroureterectomy. Endoscopic incision is the least invasive method for decompressing the ureterocele. This is an ideal method for dealing with a neonate with ureterocele-induced obstructive uropathy and sepsis. It may also be performed safely in an adult female with symptomatic ureterocele. Other indications are a single system intravesical ureterocele with obstruction or a duplex system ureterocele with indeterminate function of the affected renal moiety. Performed via the cystoscope, a small puncture is created at the base of the ureterocele. In addition to its therapeutic value, this technique may be used when the contribution of the associated renal moiety to overall renal function is indeterminate. Improvement in renal function after an incision indicates that reconstruction is favorable, if necessary, and poor function indicates that excision of the upper pole moiety is preferable. This procedure also allows palliative decompression in children at high risk (secondary to concurrent medical illness), so that definitive reconstruction can be delayed until an adequate healing period has occurred. This is the definitive therapy in only 10-40% of patients with ectopic ureteroceles, compared to 90% of the patients with a single system intravesical ureterocele. This may also be used as the definitive therapy in adults with symptomatic ureteroceles. Transurethral unroofing of a ureterocele in an adult reliably achieves decompression and allows effective treatment of infection and calculi in symptomatic ureteroceles. Low transverse incision of the ureterocele creates a "flap-valve" effect and minimizes the reflux. The actual incidence of reflux after endoscopic unroofing in ureteroceles in adults is not known since a large prospective adult series on ureteroceles is lacking. However, several case reports have alluded to the fact that the incidence of reflux appears to be proportional to the type of incision made. When a transverse (ie, smiley face) incision has been made at the base of the ureterocele, as opposed to a vertical incision, the risk of reflux is minimized. Furthermore, vesicoureteral reflux in adults has not shown higher risk for renal insufficiency or pyelonephritis. Thus, vesicoureteral reflux in adults is not routinely treated with ureteral reimplantation. Rather, these patients are monitored expectantly, and the need for reimplantation is tailored to the individual. Data on the use of bulking agents for treatment of adult vesicoureteral reflux in these situations are lacking. The potential for vesicoureteral reflux limits the use of endoscopic unroofing in children. Upper pole heminephrectomy and partial ureterectomy Upper pole heminephrectomy and partial ureterectomy with ureterocele decompression involves removal of the upper pole of the kidney, as well as the affected proximal ureter to the level of iliac vessels. The remaining distal ureterocele is not excised but rather is decompressed. This is the definitive treatment in patients with an obstructed ectopic ureterocele and a dysplastic upper pole, but without associated vesicoureteral reflux. If reflux was present preoperatively, the distal ureterocele should be ligated rather than allowing it to remain decompressed. Upper pole heminephrectomy and partial ureterectomy with ureterocele decompression is a reasonable alternative for adults in whom transurethral ureterocele unroofing has failed due to technical or anatomical difficulties. This operation has been noted to cause spontaneous resolution of ipsilateral vesicoureteral reflux and contralateral reflux and/or obstruction. Upper pole heminephrectomy and partial ureterectomy with ureterocele decompression has been reported to cause spontaneous resolution of grade I and II vesicoureteral reflux in 60% of cases, while higher grades of reflux necessitated bladder reconstruction in 96% of cases. While upper pole heminephrectomy provides effective decompression, the risk for subsequent bladder surgery may be significant, especially if reflux is already present. Factors that may predict the likelihood of future surgical intervention include the following:
Therefore, upper pole heminephrectomy is an excellent first-line procedure for the child with a ureterocele that affects only the ipsilateral upper pole. It is a good choice in the child with a ureterocele with only ipsilateral renal involvement (which may include upper pole obstruction and lower pole reflux, for example). In any case, the patient and family should be counseled about the potential need for further surgical procedures. Ureteropyelostomy is an operation that joins the upper pole ureter to the lower pole renal pelvis. This is preferred if the affected renal unit demonstrates significant function. Alternatively, a high ureteroureterostomy may also be performed. This is true for both pediatric and adult populations. Excision of the ureterocele and ureteral reimplantation Excision and ureteral reimplantation is indicated as a primary procedure if the patient has significant vesicoureteral reflux in the lower pole moiety and a well-functioning upper pole moiety and/or significant contralateral vesicoureteral reflux. Both ipsilateral ureters may be reimplanted within a common sheath or via ureteroureterostomy. Note that common sheath reimplantation has a distinct disadvantage of reimplanting a very dilated distal ureter into the small bladder of an infant. The decision whether to taper the ureters must be made on an individual basis. This operation is commonly delayed until the child is older (aged approximately 2 y). However, this operation should be performed before the child is toilet trained since it is rather extensive surgery. This operation is not commonly used in adults since most patients respond favorably to endoscopic unroofing of the ureterocele. Again, the necessity of this operation should be individualized. In the pediatric population, the excision and reimplantation procedure commonly is used as a secondary procedure (after previous heminephrectomy or endoscopic incision of a ureterocele) because of UTI, voiding disturbance, persistent vesicoureteral reflux, or obstruction. Significant vesicoureteral reflux on initial VCUG usually indicates that lower-tract reconstruction will be necessary. Of note, if this procedure is selected as the first-line treatment in the appropriate patient, the rate of secondary surgery is low. Nephroureterectomy is performed in patients with single system ureterocele and a nonfunctioning kidney. The traditional method of correcting an ectopic ureterocele in a duplex system has been to perform a total reconstruction. This involved a bladder surgery, followed by renal surgery. The bladder surgery required excision of a ureterocele, reconstruction of the detrusor, and reimplantation of the ipsilateral ureter. This was followed by a flank incision and upper pole heminephrectomy. Since most ureteroceles typically present in young children (often <1 y), total reconstruction was technically challenging, and complications were common. Briefly, a functional classification of the ectopic ureterocele by Churchill et al can be used to guide therapeutic considerations in children:2
Another consideration, in addition to the functional classification, is patient age. In the neonate or infant, transurethral puncture of the ureterocele or an upper tract approach (eg, heminephrectomy) would be the most feasible options, while excision of the ureterocele with bladder reconstruction or total reconstruction, including heminephrectomy, may be added to the therapeutic armamentarium in the older child (>2 y). In the adult, transurethral unroofing of the ureterocele is a reasonable first-line approach, because the development of postoperative vesicoureteral reflux is less problematic than in the child. Treatment of the ureterocele is individualized based on the patient age, clinical situation, functional characteristics of the ureterocele, and surgeon preference.Preoperative detailsThe goals of the preoperative evaluation of the ureterocele are as follows:
Intraoperative detailsWhen an upper tract approach is planned, preoperative function of the involved moiety and appearance of the renal parenchyma intraoperatively contribute to the decision whether to perform heminephrectomy or renal-sparing surgery (eg, ureteroureterostomy or ureteropyelostomy). The principles of successful ureteral reimplantation, with or without ureteral remodeling and bladder reconstruction, are as follows:
Endoscopic incision of ureterocele This is the least invasive technique. The patient is placed in dorsolithotomy position. Incision of the ureterocele is performed via the cystoscope. Using a small Bugbee electrode (3F) and a cutting current, create a small puncture at the lowest point just above the base of the ureterocele. Upper pole heminephrectomy, partial ureterectomy with ureterocele decompression Place the patient in a flank position. Insert a Foley catheter. Make a flank incision off the 12th rib. Mobilize the kidney and the proximal ureter. There is no need to dissect out the renal hilum. Remove the upper pole of the kidney. Manual compression of the kidney provides adequate vascular control. Next, excise the upper pole ureter to the level of the iliac vessels. Dissect on the upper pole ureter to avoid injury to the lower pole ureter. Use a catheter to decompress the distal ureterocele. If there is no reflux into the ureterocele, the stump is left open. If reflux is present, the ureterocele should be ligated. Irrigate the wound and leave a small drain in the pelvis. Ureteropyelostomy Place the patient in a supine position. Insert a Foley catheter. Make an anterior subcostal incision. Stay extraperitoneal. Dissect out both ureters. Incise the upper pole ureter laterally and incise the lower pole renal pelvis medially. Anastomose the upper pole ureter to lower pole renal pelvis. Insertion of a double J stent or a feeding tube is optional. Excision of ureterocele with ureteral reimplantation Place a patient in a supine position. Make a transverse lower abdominal incision. Open the bladder and identify the ureteral orifice and the ureterocele. Intubate both ureteral orifices with an infant feeding tube. Circumscribe out the distal ureterocele as for ureteroneocystostomy. Close the defect in the detrusor. Amputate the ureterocele. Ureters may be reimplanted within the common sheath or via ureteroureterostomy, with or without tapering of the ureter. Nephroureterectomy This procedure involves the excision of the ureterocele, the ureter, and the ipsilateral renal moiety. This is followed by reimplantation of the lower pole ureter. This technique requires 2 separate incisions (flank and lower abdominal) and is associated with fairly high morbidity. This type of total reconstruction is not commonly used today.Postoperative detailsIntravenous antibiotics are continued until the patient is discharged from the hospital. Urethral catheters are removed when urine is clear. Depending on the operation, hospital stay ranges 1-4 days. If an internal stent has been placed, it is removed 3-6 weeks after surgery. Postoperative imaging studies such as renal ultrasonography and VCUG are usually obtained at 3-4 months after surgery or sooner as dictated by individual clinical scenario or postoperative complications. Follow-upFollow-up care consists of serial monitoring of renal function, periodic evaluation of voiding symptoms and bladder function, and interval radiologic studies to assess renal growth, hydroureteronephrosis, and vesicoureteral reflux. For excellent patient education resources, visit eMedicine's Kidneys and Urinary System Center. Also, see eMedicine's patient education article Intravenous Pyelogram.COMPLICATIONSSection 8 of 13
OUTCOME AND PROGNOSISSection 9 of 13
Clearly, no single approach is appropriate for all patients with ureteroceles; therefore, each case must be tailored to the individual. An experienced surgeon must be armed with various surgical techniques (as discussed above) that can be tailored to effectively treat different types of ureterocele malformations. When an appropriate operation is used to correct a specific abnormality, the outcomes remain excellent in both pediatric and adult patients. FUTURE AND CONTROVERSIESSection 10 of 13
Although different surgical philosophies exist in managing adult and pediatric ureteroceles, the following principles may apply:
ACKNOWLEDGMENTSSection 11 of 13
The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Jong M. Choe, MD, FACS, to the development and writing of this article. MULTIMEDIASection 12 of 13
REFERENCESSection 13 of 13
Article Last Updated: Jan 27, 2008 | |||||||
