Diagnostic Ultrasound - Abdomen and Pelvis

Ureteral Duplication
TERMINOLOGY
Synonyms
• Ureteropelvic duplication, duplicated kidney, duplex or bifid
collecting system
Definitions
• Presence of 2 separate pelvicalyceal collecting systems
draining 1 kidney, which may join above bladder (partial),
drain into bladder separately (complete), or beyond bladder
IMAGING
General Features
• Best diagnostic clue
○ 2 distinct renal pelves or 2 exiting ureters in single kidney
○ 2 central echogenic renal sinuses with intervening
bridging renal parenchyma
• Other general features
○ Weigert-Meyer rule: Upper moiety ureter inserts inferior
and medial to lower moiety ureter (85%)
○ Result of Weigert-Meyer rule
– Upper pole tends to obstruct
– Lower pole tends to have vesicoureteral reflux
○ Upper moiety ureteral insertion is by definition ectopic,
and often associated with ureterocele
○ Lower moiety subjected to reflux due to its shortened
ureteric tunnel at bladder insertion
○ Kidney and ureter may be normal, except duplicated
○ 20% are bilateral
○ 40% have complete duplication
○ 60% have bifid ureter
Ultrasonographic Findings
• Grayscale ultrasound
○ Asymmetric renal enlargement
○ 2 central echogenic renal sinuses with intervening
bridging renal parenchyma
○ 2 distinct renal pelves or 2 exiting proximal ureters
○ Upper moiety commonly hydronephrotic due to
obstruction
○ Lower moiety collecting system may also be dilated due
to vesicoureteral reflux
○ With longstanding obstruction and reflux, cortical
thinning/scarring with dysplastic cystic change
○ Look for presence of ureterocele (cystic structure) in
bladder
• 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
Fluoroscopic Findings
• Voiding cystourethrogram
○ Early filling defect in bladder may reflect presence of
ureterocele
○ Look for reflux, usually occurring more often in lower
pole than upper pole
○ Drooping lily sign: Hydronephrotic upper moiety exerts
mass effect and can inferiorly displace lower pole
Nuclear Medicine Findings
• Assess relative function, drainage, and scarring, which is
important for surgical planning
Radiographic Findings
• IVP (or CT/MR urography)
○ Presence of two ureters in single kidney
– Fewer calyces & infundibula of lower pole collecting
system; shortened upper pole infundibulum
○ Poor or no excretion by upper pole moiety when
obstructed
○ Drooping lily sign: hydronephrotic upper moiety exerts
mass effect and can inferiorly displace lower pole
○ Calyceal clubbing, thin overlying parenchyma ± scarring
in lower pole
CT Findings
• "Faceless kidney": Absence of the renal sinus between
upper & lower pole
• Contrast enhancement useful to detect course of ureters
MR Findings
• T2WI
○ High signal intensity fluid within collecting system
○ Maximum-intensity projection (MIP) image and coronal
thick slab series helpful to demonstrate relative positions
of upper and lower moiety ureters
• T1 C+
○ Poor or little excretion of upper moiety when obstructed
○ Delayed images can demonstrate whole course of nondilated
ureter
Imaging Recommendations
• Best imaging tool
○ Ultrasound, IVP, or CT/MR urography
○ VCUG to exclude vesicoureteral reflux
DIFFERENTIAL DIAGNOSIS
Column of Bertin
• Prominent band of tissue does not completely divide
kidney
• Only 1 exiting ureter
Segmental Multicystic Dysplastic Kidney
• May mimic obstructed upper pole
Upper Pole Mass
• Can mimic drooping lily sign due to mass effect
Ureterocele
• Can be isolated finding
PATHOLOGY
General Features
• Etiology
○ Abnormal bifurcation of ureteral bud or 2 separate
ureteral buds arising from mesonephric duct
○ Not inherited although some familial tendency reported
• Associated abnormalities
○ Increased incidence of ureteropelvic obstruction
○ Genital anomalies found in 50% of affected females
Diagnoses: Urinary Tract
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