Urinothorax – Etiology, Clinical features and Management

Urinothorax refers to presence of urine within the pleural space

Etiology:

• Urinothorax occurs secondary to obstructive uropathy (blockage to flow of urine)
  • Urinary stones
  • Blunt trauma
  • Urinary tract surgeries

Mechanism of development of urinothorax:

• Blockage to urine flow results in leakage of urine into the retroperitoneal space forming a urinoma
• Urine then passes through the diaphragmatic lymphatics or defects in the diaphragm into the pleural space

Clinical features:

• Urinothorax causes accumulation of urine in the pleural space
• The side affected will correspond to the side where urinary obstruction is present – bilateral cases are rare
• But the classical features of pleural effusion may not be present
• Clinical examination reveals decreased respiratory movements, stony dullness on percussion and decreased/absent breath sounds

Investigations:

• Pleural fluid aspiration shows a straw coloured fluid
• Light’s criteria for transudate is fulfilled
• Confirmation is by finding a pleural fluid to serum creatinine ratio more than 1 (usually it is more than 10)

Treatment:

• Urinothorax usually resolves after the cause of urinary obstruction is removed