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Renal duplication with obstructed upper renal moiety (Weigert-Meyer rule)

Case contributed by Dr Mohammad A. ElBeialy


Recurrent urinary infection.

Patient Data

Age: 4 months
Gender: Female
  • The right kidney is enlarged and malrotated with renal duplication. The upper renal moiety shows moderate hydronephrosis and drained by a moderately dilated tortuous ureter that ends in an ectopic location within the infero-medial aspect of the urinary bladder near the bladder neck by a small about 12 X 12 X 10 mm intra-vesical ureterocele. The lower renal moiety shows no hydronephrotic changes and drained by the orthotropic ureter which is of normal course and caliber (Weigert-Meyer rule).

  • Normal left kidney. No left hydronephrosis or hydroureter.
  • The urinary bladder is seen distended with smooth regular wall.

Case Discussion

Duplex right kidney with obstructed upper moiety as well as mild right hydronephrosis and hydroureter with intra-vesical ureterocele as described. 

Weigert-Meyer Rule: with duplex kidney and complete ureteral duplication, the upper renal and lower renal moiety have their own ureters with each ureter having its own ureteral orifice in the bladder. The upper renal moiety has ectopic insertion medial and inferior to the lower pole moiety ureter and frequently ends in a ureterocele. The lower renal moiety has orthotopic insertion lateral and superior to the ureter draining the upper pole and reflux typically occurs.


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