Urinothorax

Last revised by Daniel J Bell on 14 Jan 2020

Citation, DOI, disclosures and article data

Citation:

Sharma R, Bell D, Hacking C, et al. Urinothorax. Reference article, Radiopaedia.org (Accessed on 19 Apr 2024) https://doi.org/10.53347/rID-52147

DOI:

https://doi.org/10.53347/rID-52147

Permalink:

https://radiopaedia.org/articles/52147

rID:

52147

Article created:

23 Mar 2017, Rohit Sharma ◉

Disclosures:

At the time the article was created Rohit Sharma had no recorded disclosures.

View Rohit Sharma's current disclosures

Last revised:

14 Jan 2020, Daniel J Bell ◉

Disclosures:

At the time the article was last revised Daniel J Bell had no recorded disclosures.

View Daniel J Bell's current disclosures

Revisions:

6 times, by 4 contributors - see full revision history and disclosures

Systems:

Chest, Urogenital, Trauma

Tags:

cases

Synonyms:

Urothorax
Urinothoraces
Urothoraces

Urinothorax (plural: urinothoraces), also known as urothorax, is a rare cause of pleural effusion due to the accumulation of urine within the pleural space.

The aetiology of urinothorax can be dichotomised as either due to obstructive uropathy or due to trauma (including iatrogenic post-surgical trauma) to the urinary system ^1-3. Urinothoraces are most often seen alongside urinoma, whereby the urine is thought to traverse the diaphragm into the pleural space ³. Although the pathophysiology of this remains unclear, there are two leading theories: either urine travels through lymphatic drainage into the pleural space, or retroperitoneal urine moves into the peritoneal cavity and then travels directly into the pleural space via a direct transdiaphragmatic passage along a pressure gradient ³.

Markers

The fluid in a urinothorax is usually a transudate but biochemically, often has a low pH and a high LDH and hence may be misclassified as being exudative as per Light's criteria ^2-4. However, the most important biochemical feature is the pleural fluid creatinine-to-serum creatinine ratio which is >1, with an average of 1.09–19.80 ^1-3.

Radiographic features

Plain radiograph

Chest radiographic appearance of a urinothorax is often indistinguishable form that of another cause of pleural effusion ¹. It is reported that urinothorax secondary to obstructive uropathy usually results in bilateral effusions, while those caused by trauma to the urinary tract lead to a unilateral effusion ¹, however, there have been numerous case-reports finding the opposite ⁵.

CT

Again, the appearance of urinothorax on chest CT is indistinguishable from another cause of pleural effusion. However, abdominal CT is useful to detect the cause of the urinothorax ^1-3. Many case reports describe later performing renal scintigraphy to confirm a urine leak ^1-3.

Treatment and prognosis

The exact management strategy will depend on underlying aetiology ^1-3. However, the urinothorax should be drained if symptomatic and a urology consult sought ^1-3.