When complete ureter duplication is present:
- The ureter which emanates from the superior aspect of the kidney, inserts more inferomedially into the bladder. This is referred to as the ectopic orifice.
- The other ureter, emanating from the inferior aspect of the kidney, inserts into the bladder more laterally and chephaloid (orthoptic). This ureter is more in keeping with normal ureteric insertion.
Weigert (1877) and later Meyer (1907) recognized that the disposition of the ectopic orifice to lie caudal and medial to the orthoptic orifice was almost universal in cases of ureteral duplication. This was subsequently termed the Weigert-Meyer Law.
The duplication arises during the duplication of the uteric buds, arising from the Wolffian duct (mesonephric duct). The ureters rise superiorly with the formation of the kidney
Kidneys with a double ureter system have been shown to be prone to potential complications, such as collecting system obstruction, ureterocele, lithiasis and vesicoureteral reflux.
1877 Weigert In general an ectopic orifice will lie caudal to the orthotopic orifice
1907 Meyer further described
1946 Meyer claimed that the position of the two orifices was so constant that he formulated a law, the Weigert-R. Meyer law
The situation of the two orifices is generally characteristic insofar as the upper ureter nearly always ends more caudally (Weigert, 1877), and medially (Meyer, 1907), than the lower ureter. This is known as the “Weigert-R. Meyer law.” The upper ureter opens more medially even when both ureteral orifices lie at the same level in the bladder. Since there exist few exceptions to this situation, one should call it a rule instead of a law. The importance of the exceptions is evident but they are so rare that they seemingly stress the rule.Meyer, Anatomical Record 1946
- Weigert-Meyer law
- Weigert-R. Meyer law
- Stephens law: Description of a selected number of cases which do not follow the Weigert-Meyer ‘law’ [ANZ Journal of Surgery. 1958]
- Weigert C. Über einige Bildungsfehler der Ureteren. Archiv für pathologische Anatomie und Physiologie und für klinische Medizin. 1877;70: 490-501.
- Meyer R. Zur Anatomie und Entwicklungsgeschichte der Ureterverdoppelung. Virchows Archiv für pathologische Anatomie und Physiologie und für klinische Medizin. 1907;187: 408-434.
- Meyer R. Normal and abnormal development of the ureter in the human embryo—a mechanistic consideration. The Anatomical Record. 1946;96(4):355-371
- Stephens FD. Anatomical vagaries of double Ureters. ANZ Journal of Surgery. 1958;28(1):27-33
- Haddad FS, EE Griffin. The Weigert-Meyer Law Demystified. Journal of the Islamic Medical Association of North America 1996;28(1):16-19
- Kerr AT. Complete double ureter in man. The Anatomical Record. 1911;5(2): 55-69
- Mills JC. Complete unilateral duplication of the ureter with analysis of the literature. The Urologic and cutaneous review. 1939;43: 444-447
- Lund AJ. Uncrossed double ureter with rare intravesical orifice relationship: case report with review of literature. The Journal of urology. 1949; 62(1): 22-29.
- Dougherty J. Duplication of the upper part of the urinary tract. The Journal of the International College of Surgeons 1954;21: 160-166 [PMID 13143236]
- Prakash et al. Double ureter and duplex system: a cadaver and radiological study. Urol J. 2011 Spring;8(2):145-8. [PMID 21656475]