Urinothorax is the presence of urine in the pleural space. It can occur at any age and is more common in males. It typically results from obstructive uropathy but can also be caused by malignancy or trauma. Urinothorax is a rare cause of transudative pleural effusion and the only cause of low pH (pH <7.4) transudative effusion. We present the case of a 51-year-old female patient who had recently undergone a urological procedure and came to the emergency department reporting shortness of breath. A chest X-ray revealed a newly developed, large, right-sided pleural effusion. Thoracentesis yielded a transudative yellow fluid of normal pH with a creatinine-to-serum creatinine ratio of 1.7. A computed tomography (CT) cystogram showed extravasated contrast material within the pelvis, from which a diagnosis of urinothorax was confirmed and treated. Urinothorax is a rare diagnosis that requires a multidisciplinary treatment approach, usually including a pulmonologist and a urologist. After the genitourinary disease is treated, the urinothorax usually resolves.
Keywords: bladder injury; transudative pleural effusion; urinothorax.