Presence of 2 separate pelvicalyceal collecting systems draining 1 kidney, which may join above bladder (partial), drain into bladder separately (complete), or beyond bladder

Asymmetric renal enlargement, 20% are bilateral

2 central echogenic renal sinuses with intervening bridging renal parenchyma

2 distinct renal pelves or 2 exiting ureters in single kidney

Weigert-Meyer rule: Upper moiety ureter inserts inferior and medial to lower moiety ureter

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  Upper pole tends to obstruct

  
  
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  Lower pole tends to have vesicoureteral reflux

Look for ureterocele (cystic structure) in bladder

Column of Bertin

Segmental multicystic dysplastic kidney

Hydrosalpinx (dilated ureter in pelvis)

Abnormal bifurcation of ureteral bud

Increased incidence of ureteropelvic obstruction; genital anomalies found in 50% of affected females

Symptoms include infection from reflux/stasis, hematuria, abdominal/flank pain from obstruction or calculi

Most often diagnosed on antenatal ultrasound or as incidental postnatal finding

Longstanding obstruction, reflux and infection can lead to secondary hypertension and renal insufficiency/failure

Ectopic insertion in females: Incontinence due to insertion below bladder sphincter

Ectopic insertion in males: Prostatitis, epididymitis

Young females with recurrent urinary tract infections

US, IVP or CT/MR urography are imaging modalities of choice

VCUG to exclude reflux

Color Doppler can be useful to distinguish collecting system from vessel in renal pelvis

Ureteral jets can be helpful to identify vesicoureteral junction of both upper and lower moieties