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                                  By Stephen D. Confer, MD, Dominic Frimberger, MD, and Bradley P. Kropp, MD

                                                                  While dilated ureters are usually identified
             FREE       CME ONLINE                                in adults when they present with sympto-
 To earn CME credit for this activity, participants should read   matic complaints, in children, identification
 the article and log onto,
 where they must pass a post-test. After completing the test      is most likely due to aggressive screening
 and online evaluation, a CME letter will be emailed to them.
 The release date for this activity is June 1, 2006. The          with perinatal ultrasonography (US). Urologists who primarily
 expiration date is June 1, 2007.                                 treat adults should be familiar with the principles of evaluation
 Accreditation                                                    and management options for adult, pediatric, and fetal popula-
 This activity has been planned and implemented in                tions as they may be asked to consult on a newborn or fetus with
 accordance with the Essential Areas and policies of the          a dilated ureter. See “Embryology,” page 45, for a brief review of
 Accreditation Council for Continuing Medical Education           ureteral development.
 (ACCME) through the joint sponsorship of Thomson                    A variety of terms have been applied to ureters of abnormal
 American Health Consultants (AHC) and Contemporary
 Urology. AHC is accredited by the ACCME to provide
                                                                  caliber, including megaloureter, megaureter, dilatation of the
 continuing medical education for physicians.                     ureter, and widened ureter. King has suggested the term mega-
    AHC designates this educational activity for a maximum        ureter to describe any ureter that is found to be dilated.1 This
 of 1 AMA PRA Category 1 Credit(s)™. Physicians should            broad term is defined further by 3 etiologic categories: obstructed
 only claim credit commensurate with the extent of their          megaureter, refluxing megaureter, and nonrefluxing nonobstruct-
 participation in the activity.
                                                                  ed megaureter (Table 1). Each category is further classified into
 Target audience                                                  primary and secondary subgroupings. This article focuses on di-
 This activity is designated for urologists.                      agnosis and management of primary obstructed megaureter.
 Educational objectives
 After completing the following CME activity, the reader          ETIOLOGY AND PRESENTATION
 should be able to:                                               Primary obstructed megaureter occurs in both pediatric and
 • Outline the basic embryologic development of the ureter.       adult populations.2 Rather than being caused by a lumenal ob-
 • Classify the adult and pediatric patient with a megaureter
                                                                  struction, the condition is due to an intrinsic abnormality or an
   based on the etiology of the condition.
 • Utilize imaging and clinical signs and symptoms to
                                                                  adynamic segment of the distal ureter that leads to a functional
   identify patients with primary obsructed megaureter who        obstruction. In the past, the functional obstruction was thought
   may be candidates for surveillance.                            to be similar to that seen in Hirschsprung’s disease of the colon.
 • List 3 indications that should prompt consideration of         However, this has been disproven as excised samples demon-
   repair of the primary obstructed megaureter.                   strated the presence of neural plexuses.3,4
 Faculty disclosures                                                 Approximately two thirds of reported patients are males;
 The authors (Stephen D. Confer, MD, Dominic Frimberger,          however, 1 series displayed a female predominance.5 The abnor-
 MD, and Bradley P. Kropp, MD), reviewers of CME content          mality is unilateral in approximately two thirds of cases.5 The
 (Culley C. Carson, MD and Stephen E. Strup, MD) and staff
 editors (Nancy Lucas, Editor and Beverly Lucas, Senior
 Editor) report no relationships with companies having ties to
 this field of study.

                                                                  Dr. Confer is a Resident in Urology; Dr. Frimberger is Assistant
                                                                  Professor, Section of Pediatric Urology; and Dr. Kropp is Professor
                                                                  and Chief of Pediatric Urology, Section of Urology, and Vice
                                                                  Chairman of the Department of Urology; University of Oklahoma
                                                                  Health Sciences Center, Oklahoma City.

              The most important aspect in the management of the dilated ureter in adults and
            children is identification of patients who will need and benefit from surgical repair.

presence of other anomalies, such as contralateral ureteropelvic
junction (UPJ) obstruction, renal agenesis or ectopia, and
ureteral duplication associated with primary obstructed mega-
ureters, may be seen in up to 40% of affected patients.5
   In adults, primary obstructed megaureter is usually detected                 ® Primary obstructed megaureter is
when patients present with pain or other symptoms from uri-                          caused by an intrinsic abnormality
nary tract infection (UTI), calculi, or decreased renal function.2
                                                                                     or an adynamic segment of the
In mild cases, however, patients are typically asymptomatic, and
                                                                                     distal ureter that leads to a
the condition is found during an unrelated workup.
                                                                                     functional obstruction.
   In the pediatric population, routine perinatal US has dra-
matically increased the likelihood of detection of the dilated                  ® While adults typically present with
ureter.6 The megaureter can be dilated up to 3 cm and thus is                        hematuria or symptomatic
easily identified on US as a hypoechoic cystic-appearing mass in                     complaints from UTI or stone
the retroperitoneum that may extend from the UPJ to the                              disease, most cases in children are
ureterovesical junction (UVJ).7 In a 5-year series in which US
                                                                                     detected antenatally.
was performed on 3,856 fetuses after 28 weeks of gestation, the
prevalence of primary megaureter at the level of the UVJ was
approximately 1 in 2,000.8

Several different grading systems have been promulgated, but
none is useful in predicting which patients will require surgery
and which will benefit from observation. The earliest classifica-
tion system, devised in 1978 by Pfister and Hendren, categorizes


   T   he development of the ureter begins around the fifth
       week of gestation. A diverticulum arises from the
   posteriomedial aspect of the lower portion of the bilateral
                                                                    lumen by a membrane. This membrane, known as the
                                                                    Chwalle’s membrane, disappears by the middle of
                                                                    the eighth week. At approximately the ninth week of
   mesonephric ducts. It then elongates posteriorly to meet the     gestation, muscularization is induced by the passing of
   metanephric blastema, thus inducing nephrogenesis. The tip       the first excreted urine. At 18 weeks, normal physiologic
   of the ureteric bud dilates to form the collecting system from   narrowing can be discerned at the ureteropelvic junction
   the ureterovesical junction (UVJ ) to the level of the           (UPJ) and the UVJ. It is at this time that dilation of the
   collecting duct. During the sixth through the ninth weeks,       ureter may be observed. After 19 weeks, the ureter
   the embryonic kidney ascends from its pelvic position.           continues to grow; however, the normal ureteral
     During the ascent of the kidneys, the ureters elongate.        diameter in the fetal population rarely exceeds 5 mm.1
   The lumen of the forming ureter develops from the
   midureter cranially and caudally until the eighth week.
                                                                    1. Cussen LJ. The morphology of congenital dilatation of the ureter: intrinsic le-
   The urogenital sinus remains separated from the ureteric         sions. Aust NZ J Surg. 1971;441:185-194.

                                                                                             JUNE 2006 CONTEMPORARY UROLOGY 45

     TABLE 1                                                                            ting of the renal complex. In grade 2,
     Differential diagnosis of megaureter                                               the pelvis is dilated but the calyces are
                                                                                        not dilated. In grade 3, the pelvis is
     OBSTRUCTED MEGAURETER                                                              markedly split and the calyces are uni-
                                                                                        formly dilated but the renal parenchy-
     Primary: This condition is due to an intrinsic abnormality or an adynamic
                                                                                        ma is normal. Grade 4 shares the char-
     segment of the distal ureter that leads to a functional obstruction.
                                                                                        acteristics of grade 3, but there is thin-
     Secondary: Any cause of ureteral obstruction not due to an adynamic                ning of the renal parenchyma.
     segment. Etiologies include congenital lesions (ureteropelvic junction
     obstruction, ectopic ureterocele), inflammatory conditions (tuberculosis,          EVALUATION OF PRENATALLY
     schistosomiasis, Crohn’s disease, pelvic inflammatory disease, pelvic              DIAGNOSED MEGAURETER
     abscess), trauma, tumors, lower urinary tract conditions, neurogenic               While US is highly sensitive for the de-
     bladder, benign prostatic hypertrophy, pelvic lipomatosis, and urethral            tection of a dilated ureter, it lacks speci-
     obstruction.                                                                       ficity for diseases that will actually re-
                                                                                        quire intervention. Classification of
     REFLUXING MEGAURETER                                                               megaureters based on the etiology of
     Primary: This condition occurs most often in children and describes a wide         the dilation allows the clinician to better
     ureter secondary to vesicoureteral reflux (VUR), when an abnormality of            inform patients about the treatment op-
     the ureteral orifice (or tunnel length) is the cause of the reflux.                tions and their risks and benefits. Thus,
     Secondary: Reflux due to high bladder pressures from a neurogenic                  at our institution, we recommend that
     bladder or bladder outlet obstruction.                                             newborns with prenatally diagnosed
                                                                                        megaureters undergo US and voiding
     NONREFLUXING, NONOBSTRUCTED MEGAURETER                                             cystourethrography (VCUG) within 48
                                                                                        hours of birth. If reflux is ruled out on
     Primary: Dilation not due to obstruction or reflux (prune-belly syndrome.)
                                                                                        VCUG, we proceed to DTPA diuresis
     Secondary: In this condition, ureters remain dilated after the correction of       renography to better evaluate renal
     initial pathology.                                                                 function and to determine the degree of
                                                                                        ureteral obstruction (Figure 1).

         primary obstructive megaureter in children and adults          MANAGEMENT IN ADULTS
         according to the degree of dilatation of the proximal          Adults with primary obstructed megaureter typically
         ureter.5 In grade 1, the dilatation is limited to the distal   present with pain, infection, or hematuria. Radiologic
         ureteral segment. In grade 2, the dilation extends into        evaluation (Figure 1) usually reveals pathology in the
         the proximal ureter and there may be mild caliectasis.         distal ureter. Therefore, aggressive surgical manage-
         In grade 3, the entire ureter is dilated proximal to the       ment has been recommended for adults.
         adynamic segment and there is moderate to severe                  Hemal and colleagues identified 53 of 55 adult pri-
         caliectasis. One drawback to Pfister and Hendren’s             mary obstructed megaureters on the basis of studies ob-
         grading system is that excretory urography, which is           tained to evaluate symptoms.2 While the authors advo-
         rarely necessary today, is required.                           cated surgical management in most instances, they
            The most commonly used classification for neonates,         found it unrewarding in patients with bilateral disease
                                             which is now stan-         who have advanced renal failure. Of 5 patients with bi-
                                             dard in adults, was        lateral primary obstructed megaureter and uremia, 3
  UROlogic                                   devised by the Society
                                             for Fetal Urology
                                                                        underwent ureteral reimplantation. Of that group, only
                                                                        1 improved with adequate drainage, and the other 2 pa-
                                             (SFU). It assigns a        tients died.2
® While US is highly sensitive in            grade from 0 to 4
  detecting dilated ureters, it lacks                                   MANAGEMENT IN CHILDREN
                                             based on the degree
  specificity for diseases that require
                                             of upper urinary tract     While surgery is the first-line therapy for primary ob-
  intervention. We recommend US              dilation. In grade 0,      structed megaureter in adults, the approach in children
  and VCUG within 48 hours of birth          the central renal com-     is evolving. Several studies have compared surgical
  in antenatally diagnosed infants.          plex is intact. In grade   outcomes with conservative management, but all are
                                             1, there is mild split-    retrospective and involve a considerable selection

                                             FIGURE 1
                                             Initial radiographic evaluation of suspected urologic
bias.7,9,10Nevertheless, these studies
document a shift from the traditional
approach of surgical management to
                                                                SUSPECTED UROLOGIC ABNORMALITY
the current trend of surveillance.
                                                                     (prenatal US or symptoms)
   Between 1981 and 1987, Keating
and colleagues assessed 44 renal units
in 35 neonates with primary obstruct-
ed megaureter.7 Infants with ureters                                      US shows dilation
dilated down to the UVJ with varying
degrees of hydronephrosis were in-
cluded in the study. Infants with sec-                                     Perform VCUG
ondary obstructed megaureters were
eliminated from the analysis. Antena-
tal diagnosis was made by US in 23 of
44 units. Of the 23 units, 87% were
managed nonoperatively. Diagnoses                        Reflux                              No reflux
for the remaining 21 units were made
on the basis of symptomatic com-
plaints due to UTI or the presence of a
                                                     Vesicoureteral                    Perform DTPA diuresis
flank mass, or they were incidentally                    reflux                             renography
discovered. Only 12 of the 21 sympto-
matic units were managed conserva-
tively. Subsequently, surgery was per-
formed on 2 of the 12 conservatively
managed units because of increased                                            Obstruction               No obstruction
obstruction on DTPA diuresis reno-
gram and increased dilation on US.
The authors suggested that a decision
                                                                              Obstructed                Nonobstructing,
to manage asymptomatic patients                                               megaureter                 nonrefluxing
conservatively should be based on an                                                                      megaureter
estimate of absolute renal function as
determined by diuresis renography.7
   In 1994, Baskin and associates 9
provided a long-term follow up of Keating and col- dian follow-up was 25.8 months. A total of 69 units
leagues’7 carefully selected group and found that 10 of were confirmed postnatally using various imaging
the original 35 neonates with 44 renal units ultimately modalities. Antibiotic prophylaxis was continued until
underwent surgery. The remaining 25 were observed the children were between the ages of 9 and 12 months,
and managed with serial urinary tract imaging using depending on physician’s preference. No child had a
DTPA diuresis renography, intravenous pyelography culture-documented UTI.
(IVP), and/or renal US. Seventeen of the 25 were diag-           Resolution, defined as a decrease in hydronephrosis to
nosed antenatally, 2 were identified due to infection, SFU grade 1 without hydroureter or minimal residual
and 6 incidentally diagnosed. Mean follow-up was 7.3 hydroureter, occurred in 39 (72%) patients.10 Five pa-
years for 24 patients. One patient was lost to follow-up tients (9%) had no resolution during the surveillance pe-
after 1.5 years. The conservatively managed patients riod, and 10 (19%)
demonstrated no decline of renal function on DTPA underwent surgery.
diuresis renography during the observation period. The presenting grade
The authors concluded that conservatively managed of hydronephrosis ap-
patients should be monitored closely as indications for peared to be an im-
surgical repair may arise.9                                   portant predictor of        ® Aggressive surgical management is
                                                                                             recommended for most adults with
   McLellan and co-workers evaluated the records of the resolution rate.
54 newborns who were prenatally diagnosed with pri- SFU hydronephrosis                       primary obstructed megaureter.
mary obstructed megaureter from 1993 to 1998.      10 Me-     grades 1 to 3 were

                                                                                 JUNE 2006 CONTEMPORARY UROLOGY 47

                                                                       SURGICAL METHODS OF REPAIR
                                                                        In uncomplicated nondilated ureters, reported suc-
    “Parents of children with primary obstructed                        cess rates for the various open reimplantation tech-
                                                                        niques are well over 95% in children 1 year of age or
     megaureter should be reassured that the                            older.14 However, for large dilated ureters requiring
     condition is likely to resolve spontaneously.”                     plication or tapering in addition to the usual intra-
                                                                        vesical reimplant, no conclusive data have been pub-
                                                                           Glassberg and associates reported a 99% success
         more likely to resolve within 12 to 36 months. Increasing   rate with tapering using a transverse ureteral advance-
         or severe hydronephrosis, decreasing renal function,        ment technique of ureteroneocystostomy (Cohen
         and/or retrovesical ureteral diameter greater than 1 cm     reimplant) in 7 primary obstructed megaureters.14
         seemed to correlate with the need for surgical repair.      They noted that megaureters measuring 8 to 12 mm in
            Multiple reports support conservative management         width, regardless of etiology, can be reimplanted suc-
         for primary obstructed megaureter detected in asymp-        cessfully without tapering.
         tomatic neonates.6,7,9,10 We follow these patients with        Hospitalization following reimplantation usually
         serial US and DTPA diuresis renography if increased         only requires an overnight stay. A double-pigtail
         dilation is observed on US (Figure 2). Once vesico-         ureteral stent is routinely placed and is removed at
         ureteral reflux has been excluded by VCUG, antibiotic       1 month. Ureteral reimplantation in the neonatal peri-
         prophylaxis can be discontinued.                            od can be difficult due to the discrepancy in size be-
                                                                     tween the megaureter and the small neonatal bladder.
         INDICATIONS FOR SURGERY                                        Should surgery become necessary in the neonatal
          The absolute indications for surgical intervention have    period, we recommend that a cutaneous ureterostomy
          yet to be determined. Indications for surgery suggested    be performed. This procedure is followed in the first
          by Simoni and associates include significant impair-       year of life by open intravesical reimplantation with or
          ment of urine flow on renal scan, worsening renal          without the tapering. The need for surgery is based on
          function during observation, and recurrent UTI in          initial poor renal function tests, a 10% reduction in se-
          spite of adequate antibiotic prophylaxis.11                rial renal function tests, worsening serial US findings,
             Stehr and colleagues proposed 3 indications for         and/or the presence of breakthrough infections.
          surgery using US, VCUG, IVP, and MAG-3 renal scan:
          initial impaired renal function with an obstructive pat-   CONCLUSION
          tern, normal function and at least an equivocal urinary    The most important aspect in the management of the
          drainage pattern with no improvement, or deteriora-        dilated ureter is identification of patients who will need
          tion of the urinary drainage and/or function during fol-   and benefit from surgical repair. Historically, patients
          low-up. Using these criteria, only 5 (9.6%) of 42 pa-      with dilated ureters presented with symptomatic com-
          tients were managed surgically.12                          plaints, and diagnosis preceded surgical correction.
             Liu and co-workers studied 67 units with pathology      Today, antenatal US screening identifies most cases in
                                            at the UVJ.13 Eleven     children. The antenatal diagnosis of a dilated ureter
                                            (17%) patients failed    with or without hydronephrosis warrants postnatal
  UROlogic                                  conservative therapy
                                            and required surgical
                                                                     confirmation by US and institution of antibiotic pro-
                                                                     phylaxis. Ominous signs include bilaterally dilated sys-
                                            repair—3 due to          tems, anuria, maternal oligohydramnios, or poor renal
® In most antenatally diagnosed             breakthrough infec-      function, and necessitate more aggressive evaluation
  children, the condition resolves          tions and 8 because      within the first 48 hours of life.
  spontaneously. Consequently,              of deteriorating func-      Most patients with primary obstructed megaureter
  asymptomatic patients can be              tion.8 The remaining     detected antenatally can be followed conservatively
  followed conservatively with US.          56 (83%) patients        with US. DTPA diuresis renography may be performed
  If dilation increases on US, DTPA         were managed con-        after identification of increased dilation on US. Follow-
  diuresis renography should be             servatively by period-   ing antenatal diagnosis of primary obstructed mega-
  performed.                                ic followup with US      ureter, 72% resolve spontaneously, 19% will need op-
                                            and DTPA diuresis        erative repair, and 9% will have persistent dilation on
                                            renography.              imaging without symptoms or deterioration of func-

    FIGURE 2
    Management of primary megaureter

                                                           US, VCUG, and DTPA diuresis renography

                                                                        Primary megaureter

                                                        Low- to mid-grade ureteral                                                   High-grade ureteral
                                                               obstruction                                                               obstruction

                      Perform serial US                       Worsening renal                         Infection or pain
                           imaging                               function

                                                                                                                                        Surgical repair

        Improvement or                     Resolution of                    Increased dilation                                      Decreased function
          no change                         obstruction                                                                            ( >10%) or increased

                                             No further                         DTPA diuresis
                                              imaging                            renography

tion.13 Predictors for the need for surgical management                           5. Pfister RC, Hendren WH. Primary megaureter in children and adults. Clini-
                                                                                 cal and pathophysiologic features of 150 ureters. Urology. 1978;12(2):
include severe or worsening hydronephrosis, ureteral                             160-176.
dilation greater than 1 cm in diameter, and worsening                             6. Manzoni C. Megaureter. Rays. 2002;27(2):83-85.
renal function.10                                                                 7. Keating MA, Escala J, Snyder HM et al. Changing concepts in management
                                                                                 of primary obstructive megaureter. J Urol. 1989;142(2 pt 2):636-640.
   While aggressive surgical management is usually
                                                                                  8. Gunn TR, Mora JD, Pease P. Antenatal diagnosis of urinary tract abnormali-
recommended for adults with primary obstructed                                   ties by ultrasonography after 28 weeks’ gestation: incidence and outcome.
megaureter, parents of children with the condition                               Am J Obstet Gynecol. 1995;172(2 pt 1):479-486.
                                                                                  9. Baskin LS, Zderic SA, Snyder HM, et al. Primary dilated megaureter: long
should be reassured that it is likely to resolve sponta-                         term followup. J Urol. 1994;152(2 pt 2):618-621.
neously. However, surgical management, when indi-                                10. McLellan DL, Retik AB, Bauer SB, et al. Rate and predictors of sponta-
cated, is usually successful.                        CU                          neous resolution of prenatally diagnosed primary nonrefluxing megaureter.
                                                                                 J Urol. 2002;168(5):2177-2180.
                                                                                 11. Simoni F, Vino L, Pizzini C, et al. Megaureter: classification, pathophysiolo-
REFERENCES                                                                       gy, and management. Pediatr Med Chir. 2000;22(1):15-24.
 1. King LR. Megaloureter: definition, diagnosis and management. J Urol.         12. Stehr M, Metzger R, Schuster T, et al. Management of the primary ob-
1980;123(2):222-223.                                                             structed megaureter (POM) and indications for operative treatment. Eur J Pe-
 2. Hemal AK, Ansari MS, Doddamani D, et al. Symptomatic and complicated         diatr Surg. 2002;12(1):32-37.
adult and adolescent primary obstructive megaureter—indications for surgery:     13. Liu HY, Dhillon HK, Yeung CK, et al. Clinical outcome and management
analysis, outcome, and follow-up. Urology. 2003;61(4):703-707.                   of prenatally diagnosed primary megaureters. J Urol. 1994;152(2 pt 2):614-
 3. Dunnick NR, McCallum RW, Sandler CM. Textbook of Uroradiology. 1st           617.
ed. Baltimore, Md: Williams & Wilkins; 1991.                                     14. Glassberg KI, Laungani G, Wasnick RJ, et al. Transverse ureteral advance-
 4. Leibowitz S, Bodian M. A study of the vesical ganglia in children and the    ment technique of ureteroneocystostomy (Cohen reimplant) and a modifica-
relationship to the megaureter megacystis syndrome and Hirschsprung’s dis-       tion for difficult case (experience with 121 ureters). J Urol. 1985; 134(2):
ease. J Clin Pathol. 1963;16:342-350.                                            304-307.

                                                                                                                 JUNE 2006 CONTEMPORARY UROLOGY 49

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