Aberrant location of kidney

Separated into multiple categories, of which simple renal ectopia (RE) and crossed-fused ectopia (CFE) are most common

Absence of kidney in expected renal fossa

RE can range in location from pelvic (most common) to thoracic (rare)

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  Kidney is 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

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  Kidney located contralateral to its ureteral insertion

  
  
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  Left kidney more commonly ectopic than right

CECT and CEMR with urography can better delineate ureteral course and presence of crossing vessels

Renal transplant (iatrogenic ectopia)

Horseshoe kidney

Ptotic kidney

Acquired renal displacement

Arrested migration during embryologic development

Other genitourinary abnormalities in ~ 1/2 of cases

RE

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  Vesicoureteral reflux (most common associated abnormality)

  
  
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  Contralateral renal abnormalities in up to 50% of RE, such as renal agenesis

  
  
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  Absent or hypoplastic vagina

CFE

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  Megaureter, cryptorchidism, urethral valves, multicystic dysplasia

Occurs in conjunction with anomalies in other organs in ~ 1/3 of cases

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  Skeletal (up to 50%)

  
  
  
  
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    Rib and vertebral anomalies; scoliosis may impact renal ascent

    
    
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    Absence of radius

  
  
  
  
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  Cardiovascular (40%)

  
  
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  Gastrointestinal (33%)

  
  
  
  
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    Anorectal malformations such as imperforate anus

  
  
  
  
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  Ears, lips, palate (33%)

CFE is 2nd most common fusion abnormality

Associated with anomalies in genitourinary tract in ~ 1/2 of cases and other organ systems in up to 1/3

Most common coincident urological abnormality in RE is vesicoureteral reflux

Commonly asymptomatic, incidental finding

~ 50% have complications related to vesicoureteral reflux, hydronephrosis, stones, and infection

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  May have increased susceptibility to trauma

Contralateral renal abnormalities in RE up to 50%

Treat complications with no need to separate fused components

When renal fossa is empty, look for ectopic kidney