Urinomas (or uriniferous fluid collections) are usually found in  the retroperitoneum, most commonly in the perirenal space.

As urine extravasates into the retroperitoneum, it can cause lipolysis of the surrounding fat with resultant encapsulation of urine, forming a urinoma.

Urinomas most often due to urinary obstruction secondary to 2-3:

Urinomas also may be due to:

Location and morphology
  • cystic mass in perirenal space: localized perirenal urinoma (most common)
  • cystic mass filling entire perirenal space: diffuse perirenal urinoma
  • sickle-shaped collection: subcapsular urinoma
  • encapsulated expanding intrarenal cystic mass separating renal tissue fragments: intrarenal urinoma 3
CT and MRI

On CT and MRI, a urinoma  shows water attenuation, low  signal intensity on T1-weighted imaging, and  very high  signal intensity on T2-weighted imaging, similar to simple fluid elsewhere in the body.

Urine leakage is usually directly demonstrated on contrast-enhanced CT or T1-weighted imaging, seen as enhancement of the fluid during the excretory phase of enhancement due to contrast extravasation from the lumen of the genitourinary system 2.

IVU

Contrast extravasates outside of the collecting system, into the surrounding retroperitoneal tissues.

  • small urinomas: usually treated conservatively
  • larger, persistent or symptomatic urinomas: percutaneous drainage is often used with treatment of the underlying cause of urine leakage
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Article Information

rID: 21472
System: Urogenital
Section: Pathology
Tag: urinoma
Synonyms or Alternate Spellings:
  • Urinomas
  • Uriniferous fluid collections

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    Case 4: post traumatic urinoma
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