Last updated: December 1, 2022

Summarytoggle arrow icon

Megaureter is defined as ureteral dilation > 7 mm. Primary megaureter is due to obstructed or refluxing vesicoureteral junction, while secondary megaureter is caused by bladder outlet obstruction. Although rare, primary megaureter is responsible for up to 20% of hydronephrosis cases in neonates. About half of the patients with megaureter are asymptomatic. The other half may present with a urinary tract infection, abdominal pain, or features of uremia. Ultrasound (prenatal and postnatal) shows ureteral dilation, which may be accompanied by hydronephrosis. CT or MR urography shows a constricted terminal ureter with proximal dilation, while voiding cystogram detects vesicoureteral reflux in refluxing megaureter. Prophylactic antibiotics and regular follow-ups are sufficient in patients with primary megaureter and preserved renal function. Surgery (terminal ureter resection and reimplantation into the bladder) is indicated in patients with deteriorating renal parameters. Patients with secondary megaureter require treatment of the underlying cause. Those who do not receive treatment can develop recurrent urinary tract infections, hydronephrosis, and obstructive nephropathy with permanent kidney damage.

Definitiontoggle arrow icon

  • Ureteral dilation > 7 mm in children [1]

Epidemiologytoggle arrow icon

Epidemiological data refers to the US, unless otherwise specified.

Etiologytoggle arrow icon

Primary megaureter

  • Primary obstructed megaureter
    1. Congenital developmental defect of the muscular layer of the terminal ureter
    2. Distal aperistaltic segment of ureter causing functional obstruction
    3. Increased intraureteral pressure in dilation
  • Primary refluxing megaureter: dilation of the ureter secondary to primary vesicoureteral reflux (VUR)

Secondary megaureter


Clinical featurestoggle arrow icon

Diagnosticstoggle arrow icon

Treatmenttoggle arrow icon

Primary megaureter

  • Conservative therapy
    • Indicated in children with preserved renal function
    • Prophylactic antibiotics
    • Regular follow-up
  • Surgery
    • Indicated in children with deteriorating renal function
    • Procedure: resection of the distal segment of the ureter and re-implantation into the bladder (ureteroneocystostomy)

Secondary megaureter

  • Treatment of the underlying disease

Complicationstoggle arrow icon

We list the most important complications. The selection is not exhaustive.

Referencestoggle arrow icon

  1. Cussen LJ. Dimensions of the normal ureter in infancy and childhood.. Invest Urol. 1967; 5 (2): p.164-78.
  2. Stoll C, Alembik Y, Roth MP, Dott B, Sauvage P. Risk factors in internal urinary system malformations.. Pediatr Nephrol. 1990; 4 (4): p.319-23.doi: 10.1007/BF00862508 . | Open in Read by QxMD
  3. Gimpel C, Masioniene L, Djakovic N, et al. Complications and long-term outcome of primary obstructive megaureter in childhood.. Pediatr Nephrol. 2010; 25 (9): p.1679-86.doi: 10.1007/s00467-010-1523-0 . | Open in Read by QxMD
  4. Megaureter. Updated: November 28, 2016. Accessed: April 7, 2017.
  5. Shokeir AA, Nijman RJM. Primary megaureter: current trends in diagnosis and treatment. BJU Int. 2001; 86 (7): p.861-868.doi: 10.1046/j.1464-410x.2000.00922.x . | Open in Read by QxMD

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 Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer