Diagnostic Ultrasound - Abdomen and Pelvis

Renal Ectopia
Diagnoses: Urinary Tract
TERMINOLOGY
• Renal ectopia (RE), crossed fused ectopia (CFE)
• Separated into multiple categories, of which simple RE and
CFE represent most common forms
IMAGING
• Best diagnostic clue: Absence of kidney in expected renal
fossa
• RE can range in location from pelvic (most common) to
thoracic (rare)
• Simple RE: Kidney located ipsilateral to its ureteral insertion
• CFE: Ectopic kidney is malrotated; usually fusion of upper
pole of ectopic kidney to lower pole of normally positioned
kidney
○ Kidney located contralateral to its ureteral insertion
○ Left kidney more commonly ectopic than right
• CECT and CEMR with urography can better delineate
ureteral course and presence of crossing vessels
KEY FACTS
TOP DIFFERENTIAL DIAGNOSES
• Renal transplant (iatrogenic ectopia)
• Horseshoe kidney
• Ptotic kidney
• Acquired renal displacement
PATHOLOGY
• Most common coincident urological abnormality in RE is
vesicoureteral reflux
• Contralateral renal abnormalities in RE up to 50%
• Abnormalities in other organ systems in up to 1/3
CLINICAL ISSUES
• Treat complications
• No need to separate fused components
(Left) Graphic shows inferior
crossed fused renal ectopia.
Note the left ureter inserts on
the opposite side, in its normal
location. (Right) Grayscale
ultrasound image
demonstrates crossed fused
renal ectopia on the right.
Note the anterior orientation
of the renal pelvis .
(Left) Grayscale ultrasound
image demonstrates ectopic
location of the left kidney ,
which is situated within the
pelvis. (Right) Voiding
cystourethrogram performed
in the same patient
demonstrates grade 2 reflux
into the ectopic left kidney .
428