Spot the diagnosis in the following IVU study?

Note the bilaterally dilated distal ureters, and comparatively the PC system, upper and mid ureters are normal - findings suggest megaureter. Congenital megaureter is a rare oddity that may be bilateral and associated with other congenital anomalies. Functional obstruction at the lower end of the ureter ends in progressive dilatation and infection. The ureteric orifice appears normal and a ureteric catheter passes easily. Reflux is not a feature of the untreated condition but occurs if the ureteric orifice is opened endoscopically. Spontaneous improvement occurs but infection or deteriorating function will require refashioning and reimplantation of the affected ureter.