A 35-year-old woman with recurrent urinary tract infections undergoes intravenous urography. The pelvicalyceal system of the right kidney is duplex, with two separate collecting systems joining to form a single ureter at the mid-ureter. The upper pole moiety drains into the bladder at an ectopic location medially and inferiorly to the normal ureteral orifice. Which rule describes the relative orifice positions of a duplex system?
- A Meyer-Weigert rule
- B Batson rule
- C Weigert-Meyer rule ✓
- D Bergman rule
Correct answer: C. Weigert-Meyer rule
Explanation
The Weigert-Meyer rule states that in a duplex kidney, the upper pole ureter inserts ectopically into the bladder at a position medial and inferior to the normal trigonal position, while the lower pole ureter inserts at the normal trigonal position. The upper pole ureter is prone to an ectopic ureterocele and obstruction, while the lower pole ureter is prone to vesicoureteric reflux due to its shorter intramural tunnel. This rule is fundamental to understanding the complications of duplex collecting systems in urological radiology.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.