Due to the future lower pole ureter
separating from the Wolffian duct earlier, it migrates superiorly and laterally as the urogenital sinus grows and becomes the upper pole moiety.
This results in the upper pole ureter having an opening that is more caudal than the lower pole ureter
(Weigert Meyer Rule) .
Interestingly, and explaining the Weigert-Meyer rule, the future lower pole ureter
separates from the Wolffian duct earlier and migrates superiorly and laterally as the urogenital sinus grows.
All patients undergo cystoscopic evaluation with retrograde ureteropyelogram and open-ended ureteral catheter placement into the lower pole ureter
prior to robotic intervention.
Classically, the ureterocele of the upper pole ureter results in obstruction, while abnormal insertion of the lower pole ureter
results in vesicoureteral reflux (Weigert-Meyer rule).