In complete ureteral duplication with each segment having its own ureteral orifice in the bladder, the Weigert-Meyer rule applies.
- Upper Pole Moiety
- Inserts medial and inferiorly to the lower pole moiety
- frequently ends in a ureterocele
- Lower Pole Moiety
- Inserts lateral and superiorly to the ureter draining the upper pole
- reflux typically occurs
- A mnemonic tool for remembering this rule is UMILO: The Upper pole moeity inserts Medially and Inferiorly while the Lower pole moeity inserts Orthotopically. "Weigert and Meyer had a baby named Umilo."
-  - Teresa Berrocal, Pedro López-Pereira, Antonia Arjonilla, and Julia Gutiérrez Anomalies of the Distal Ureter, Bladder, and Urethra in Children: Embryologic, Radiologic, and Pathologic Features RadioGraphics 2002; 22: 1139.
-  - SK Fernbach, KA Feinstein, K Spencer, and CA Lindstrom Ureteral duplication and its complications RadioGraphics 1997; 17: 109.
- Edward Iuliano Chief resident educational conversation St. Barnabas Radiology Department Bronx, N.Y. 2003.