Q: When is CT urography indicated for hematuria? show answer
Ectopic kidney (sacral kidney)
Patient presented with gross hematuria. No fever or WBC on urinalysis.
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The right kidney has not ascended to its normal position in the right upper quadrant, and instead has only risen as high as the lower lumbar spine and sacrum ( closer to a "sacral kidney" than a "pelvic kidney").
The collecting system is oriented anteriorly, which is the normal orientation as a kidney ascends. As a kidney ascends, it rotates medially into its normal position.
The ectopic kidney receives arterial supply from the distal aorta, but its renal vein crosses behind the kidney to drain into the ipsilateral proximal common iliac vein.
This was an isolated finding, and the study was otherwise normal: no other abnormality in the kidneys, ureter, or bladder.
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The term "renal ectopia" encompasses a wide variety of developmentally malpositioned kidneys. The kidneys originate in the fetal pelvis and rise to their normal position early in gestation. The most common type of malpositioning is a "pelvic kidney", in which a kidney fails to rise to its normal position.
Renal ectopia is associated with other abnormalities of development, but in itself is not pathologic. Depending of the nature of the malpositioning, the kidney may be at increased risk for
- obstruction (through compression of the upper collecting system by adjacent structures)
- reflux (abnormal relationship with the ureterovesicular junction (UVJ))
In this case, no ureteral stone, mass, or blood clot is present in the urinary system and the gross hematuria was considered to be due to some occult stress on the pelvic kidney.