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Pediatrics
Diagnosis
Genitourinary
Congenital Urinary Tract Abnormalities
Primary Megaureter
Primary Megaureter
Steven J. Kraus, MD
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KEY FACTS

  • Terminology

    • Imaging

      • Clinical Issues

        TERMINOLOGY

        • Synonyms

          • Congenital megaureter, ureteral achalasia

        • Definitions

          • Megaureter: Ureteral diameter ≥ 7 mm
          • 4 types classified by presence of vesicoureteral reflux (VUR) &/or obstruction
            • Nonrefluxing obstructed (NR, O)
            • Refluxing obstructed (R, O)
            • Refluxing nonobstructed (R, NO)
            • Nonrefluxing nonobstructed (NR, NO)
          • Primary obstructive megaureter: Congenital functional obstruction at juxtavesical segment of ureter
            • Presumably due to absent peristalsis in normal-caliber distal segment, though exact etiology is unclear

        IMAGING

        • General Features

          • Radiographic Findings

            • Ultrasonographic Findings

              • Fluoroscopic Findings

                • Nuclear Medicine Findings

                  • MR Findings

                    • Imaging Recommendations

                      DIFFERENTIAL DIAGNOSIS

                        PATHOLOGY

                        • General Features

                          • Microscopic Features

                            CLINICAL ISSUES

                            • Presentation

                              • Demographics

                                • Natural History & Prognosis

                                  • Treatment

                                    Selected References

                                    1. Torino G et al: High-pressure balloon dilatation for the treatment of primary obstructive megaureter: is it the first line of treatment in children and infants? Swiss Med Wkly. 151:w20513, 2021
                                    2. Dekirmendjian A et al: Primary non-refluxing megaureter: analysis of risk factors for spontaneous resolution and surgical intervention. Front Pediatr. 7:126, 2019
                                    3. Teklali Y et al: Endoscopic management of primary obstructive megaureter in pediatrics. J Pediatr Urol. 14(5):382-7, 2018
                                    4. Babu R: 'Mini reimplantation' for the management of primary obstructed megaureter. J Pediatr Urol. 12(2):103.e1-4, 2016
                                    5. Emad-Eldin S et al: Diagnostic value of combined static-excretory MR Urography in children with hydronephrosis. J Adv Res. 6(2):145-53, 2015
                                    6. Kart Y et al: Altered expression of interstitial cells of Cajal in primary obstructive megaureter. J Pediatr Urol. 9(6 Pt B):1028-31, 2013
                                    7. Wildbrett P et al: Impact of magnetic resonance urography and ultrasonography on diagnosis and management of hydronephrosis and megaureter in paediatric patients. Afr J Paediatr Surg. 9(2):122-7, 2012
                                    8. Gimpel C et al: Complications and long-term outcome of primary obstructive megaureter in childhood. Pediatr Nephrol. 25(9):1679-86, 2010
                                    9. Hodges SJ et al: Megaureter. ScientificWorldJournal. 10:603-12, 2010
                                    10. Khrichenko D et al: Functional analysis in MR urography - made simple. Pediatr Radiol. 40(2):182-99, 2010
                                    11. Neulander EZ et al: Upper pole multicystic dysplasia and ureteropelvic junction obstruction associated with obstructive-refluxing megaureter in a neonate with a single kidney. Can J Urol. 17(6):5472-4, 2010
                                    12. Vlad M et al: Morphological study of congenital megaureter. Rom J Morphol Embryol. 48(4):381-90, 2007
                                    13. Kocaoglu M et al: Intravenous contrast-enhanced dynamic MR urography: diagnosis of vesicoureteral reflux during bladder filling with time-signal intensity curves. J Magn Reson Imaging. 24(2):349-55, 2006
                                    14. Merlini E et al: Primary non-refluxing megaureters. J Pediatr Urol. 1(6):409-17, 2005
                                    15. Shukla AR et al: Prenatally detected primary megaureter: a role for extended followup. J Urol. 173(4):1353-6, 2005
                                    16. McLellan DL et al: Rate and predictors of spontaneous resolution of prenatally diagnosed primary nonrefluxing megaureter. J Urol. 168(5):2177-80; discussion 2180, 2002
                                    17. Shokeir AA et al: Primary megaureter: current trends in diagnosis and treatment. BJU Int. 86(7):861-8, 2000
                                    18. Simoni F et al: Megaureter: classification, pathophysiology, and management. Pediatr Med Chir. 22(1):15-24, 2000
                                    19. Meyer JS et al: Primary megaureter in infants and children: a review. Urol Radiol. 14(4):296-305, 1992
                                    20. Blickman JG et al: The coexistence of primary megaureter and reflux. AJR Am J Roentgenol. 143(5):1053-7, 1984
                                    21. UpToDate: Primary megaureter in infants and children. Published July 2, 2019. Reviewed July 2021. Accessed July 26, 2021. http://www.uptodate.com/contents/primary-megaureter-in-infants-and-children
                                    22. Orphanet: Congenital primary megaureter . Published May 2010. Accessed July 26, 2021. http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=617
                                    23. RSNA RadioGraphics: Pediatric MR Urography: Indications, Techniques, and Approach to Review. Published July 14, 2015. Accessed July 26, 2021. http://dx.doi.org/10.1148/rg.2015140223
                                    Related Anatomy
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                                    Related Differential Diagnoses
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                                    References
                                    Tables

                                    Tables

                                    KEY FACTS

                                    • Terminology

                                      • Imaging

                                        • Clinical Issues

                                          TERMINOLOGY

                                          • Synonyms

                                            • Congenital megaureter, ureteral achalasia

                                          • Definitions

                                            • Megaureter: Ureteral diameter ≥ 7 mm
                                            • 4 types classified by presence of vesicoureteral reflux (VUR) &/or obstruction
                                              • Nonrefluxing obstructed (NR, O)
                                              • Refluxing obstructed (R, O)
                                              • Refluxing nonobstructed (R, NO)
                                              • Nonrefluxing nonobstructed (NR, NO)
                                            • Primary obstructive megaureter: Congenital functional obstruction at juxtavesical segment of ureter
                                              • Presumably due to absent peristalsis in normal-caliber distal segment, though exact etiology is unclear

                                          IMAGING

                                          • General Features

                                            • Radiographic Findings

                                              • Ultrasonographic Findings

                                                • Fluoroscopic Findings

                                                  • Nuclear Medicine Findings

                                                    • MR Findings

                                                      • Imaging Recommendations

                                                        DIFFERENTIAL DIAGNOSIS

                                                          PATHOLOGY

                                                          • General Features

                                                            • Microscopic Features

                                                              CLINICAL ISSUES

                                                              • Presentation

                                                                • Demographics

                                                                  • Natural History & Prognosis

                                                                    • Treatment

                                                                      Selected References

                                                                      1. Torino G et al: High-pressure balloon dilatation for the treatment of primary obstructive megaureter: is it the first line of treatment in children and infants? Swiss Med Wkly. 151:w20513, 2021
                                                                      2. Dekirmendjian A et al: Primary non-refluxing megaureter: analysis of risk factors for spontaneous resolution and surgical intervention. Front Pediatr. 7:126, 2019
                                                                      3. Teklali Y et al: Endoscopic management of primary obstructive megaureter in pediatrics. J Pediatr Urol. 14(5):382-7, 2018
                                                                      4. Babu R: 'Mini reimplantation' for the management of primary obstructed megaureter. J Pediatr Urol. 12(2):103.e1-4, 2016
                                                                      5. Emad-Eldin S et al: Diagnostic value of combined static-excretory MR Urography in children with hydronephrosis. J Adv Res. 6(2):145-53, 2015
                                                                      6. Kart Y et al: Altered expression of interstitial cells of Cajal in primary obstructive megaureter. J Pediatr Urol. 9(6 Pt B):1028-31, 2013
                                                                      7. Wildbrett P et al: Impact of magnetic resonance urography and ultrasonography on diagnosis and management of hydronephrosis and megaureter in paediatric patients. Afr J Paediatr Surg. 9(2):122-7, 2012
                                                                      8. Gimpel C et al: Complications and long-term outcome of primary obstructive megaureter in childhood. Pediatr Nephrol. 25(9):1679-86, 2010
                                                                      9. Hodges SJ et al: Megaureter. ScientificWorldJournal. 10:603-12, 2010
                                                                      10. Khrichenko D et al: Functional analysis in MR urography - made simple. Pediatr Radiol. 40(2):182-99, 2010
                                                                      11. Neulander EZ et al: Upper pole multicystic dysplasia and ureteropelvic junction obstruction associated with obstructive-refluxing megaureter in a neonate with a single kidney. Can J Urol. 17(6):5472-4, 2010
                                                                      12. Vlad M et al: Morphological study of congenital megaureter. Rom J Morphol Embryol. 48(4):381-90, 2007
                                                                      13. Kocaoglu M et al: Intravenous contrast-enhanced dynamic MR urography: diagnosis of vesicoureteral reflux during bladder filling with time-signal intensity curves. J Magn Reson Imaging. 24(2):349-55, 2006
                                                                      14. Merlini E et al: Primary non-refluxing megaureters. J Pediatr Urol. 1(6):409-17, 2005
                                                                      15. Shukla AR et al: Prenatally detected primary megaureter: a role for extended followup. J Urol. 173(4):1353-6, 2005
                                                                      16. McLellan DL et al: Rate and predictors of spontaneous resolution of prenatally diagnosed primary nonrefluxing megaureter. J Urol. 168(5):2177-80; discussion 2180, 2002
                                                                      17. Shokeir AA et al: Primary megaureter: current trends in diagnosis and treatment. BJU Int. 86(7):861-8, 2000
                                                                      18. Simoni F et al: Megaureter: classification, pathophysiology, and management. Pediatr Med Chir. 22(1):15-24, 2000
                                                                      19. Meyer JS et al: Primary megaureter in infants and children: a review. Urol Radiol. 14(4):296-305, 1992
                                                                      20. Blickman JG et al: The coexistence of primary megaureter and reflux. AJR Am J Roentgenol. 143(5):1053-7, 1984
                                                                      21. UpToDate: Primary megaureter in infants and children. Published July 2, 2019. Reviewed July 2021. Accessed July 26, 2021. http://www.uptodate.com/contents/primary-megaureter-in-infants-and-children
                                                                      22. Orphanet: Congenital primary megaureter . Published May 2010. Accessed July 26, 2021. http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=617
                                                                      23. RSNA RadioGraphics: Pediatric MR Urography: Indications, Techniques, and Approach to Review. Published July 14, 2015. Accessed July 26, 2021. http://dx.doi.org/10.1148/rg.2015140223