Congenital Megaureter

  • Etiology:
    — Distal ureteral obstruction due to non-peristaltic segment (like a ureteral Hirschsprung)
    — Can be associated with vesicoureteral reflux = refluxing megaureter
    — 4 types: Refluxing obstructed, refluxing non-obstructed, non-refluxing obstructed, non-refluxing non-obstructed
  • Imaging:
    — Megaureter greater than 7 millimeters diameter which is not as tortuous as same dilation from reflux
    — Non-peristaltic segment involves last 0.5 centimeter to 4 centimeters of ureter which is normal caliber and which may cause obstruction
    — Vesicoureteral reflux in 5-10%
    — Varying degrees of renal parenchymal thinning and scarring
  • Imaging MAG3 scan: Look at renal function and drainage
  • DDX: Vesicoureteral reflux
  • Complications:
  • Treatment: Some resolve on their own, if there is severe obstruction leading to progressive nephropathy then surgical resection and reimplantation
  • Clinical:
    — More common in males
    — 70% resolve by 7 years of age especially if less than 8.5 millimeters at diagnosis

Radiology Cases of Congenital Megaureter

Excretory phase image from an intravenous pyelogram shows marked dilation of the left renal collecting system and marked dilation of the left ureter throughout its course when compared to the right ureter. No vesicoureteral reflux was seen on a voiding cystourethrogram.
US of congenital megaureter
Sagittal US of the left kidney (above) and left ureterovesical junction (below) show moderate hydroureteronephrosis. There was no evidence of a urinary tract stone. A subsequent voiding cystourethrogram showed no evidence of vesicoureteral reflux.

US of congenital megaureter
Sagittal US of the left kidney (above) and left ureteropelvic junction (below) show moderate hydroureteronephrosis. There was moderate hydroureter all the way to the ureterovesical junction. A subsequent voiding cystourethrogram showed no evidence of vesicoureteral reflux.