Monday July 12, 2010

Q: What is urinothorax?


Answer: Presence of urine in pleural cavity is called Urinothorax. Urinothorax can occur from urinary tract injury or obstruction - and leakage of urine from the peritoneal and retroperitoneal space into the pleural space.

Urinothorax usually causes a rapidly accumulating pleural effusion. Most cases of urinothorax are due to obstruction, secondary to tumor/metastasis, or trauma of the ureter. In other cases, retroperitoneal fibrosis, shock wave lithotripsy, and removal/blockage of nephrostomy tubes may result in the formation of an urioma. Nephropleural fistula may form, allowing urine to enter the pleural cavity. Accidental placement of nephrostomy tubes too cephalically in the thorax may cause urinthorax too.


Diagnosis: Urinothorax should be suspected if the sample is straw colored or has a urine-like odor. Measurement of pleural creatinine to serum creatinine has been found to be the most reliable laboratory value and should be the definitive evaluation of urinothorax. Pleural fluid/serum creatinine ratio higher than 1 is diagnostic in association with other features. Moreover urinothorax may be both transudative and acidic (lower than 7.30).