Duplicated Kidney

  • Etiology: congenital
  • Weigert Meyer rule
  • — Ureter draining upper pole inserts ectopically (abnormally) medial + inferior to lower pole moiety ureter and frequently ends in ureterocele which can cause ureteral obstruction + upper pole hydronephrosis + may insert into urethra or vagina
  • — Ureter draining lower pole inserts in orthotopic (normal) trigonal position + is prone to reflux
  • Imaging: drooping lily sign – obstructed nonfunctional upper pole moiety in duplex system displaces the functional opacified lower pole moiety inferolaterally
  • US: interruption of central echogenic fat surrounding collecting system

Cases of Duplicated Kidney

US of duplicated kidney with ectopic ureterocele and hydroureteropyonephrosis
Sagittal US of the right kidney (upper left) shows a duplicated renal collecting system with the upper pole replaced by a round structure filled with echogenic material. Sagittal US of the right upper pole ureter (upper right) shows a tortuous ureter filled with echogenic material. Transverse US of the bladder (lower left) shows a round structure in the right side of the bladder that has echogenic material in its inferior portion and anechoic material in its superior portion. Sagittal US of the right ureter and bladder (lower right) shows the tortuous right ureter filled with echogenic material on the left side of the image and the rounded structure with the fluid-fluid level in the right side of the bladder.