Key maging findings in primary megaureter. From Merrow AC Jr. Diagnostic Imaging: Pediatrics. 3rd ed. Elsevier; 2017.

1. Primary megaureter
– imaging findings

2. functional obstruction due to aperistalsis
of the terminal 0.5-4 cm of ureter
commonly unilateral
more common on the left

3. US, IVU, MRU
dilated ureter with prevesical
transition to aperistaltic
normal caliber ureter

4. IVU, diuretic renography, MRU
delayed clearance of contrast
from dilated ureter

5. +/- hydronephrosis on US, IVU, MRU
+/- vesicoureteral reflux on VCUG

6. less common than megaureter secondary to
vesicoureteral reflux
less severe than megaureter secondary to
vesicoureteral reflux

7. if initial ureteral diameter < 8,5 mm
 likely to resolve by age 7
If initial ureteral diameter > 15 mm
 likely to persist