Case Presentation:

A 44–year–old male with history of obstuctive uropathy presented with dyspnea, left sided chest pain, flank pain and hypoxia a day after an urologic procedure. His percutaneous nephrostomy tube was removed 1 day prior to his presentation. His chest x’ray showed a new left pleural effusion. CT angiogram showed no evidence of pulmonary emboli. Pt was admitted to the medical floor for pain control and thoracentesis. There was concern that given his recent removal of the percutaneous nephrostomy tube, an unintentional nephropleuric fistula had been created leading to entry of urine into the pleural space causing the patient’s symptoms and hypoxia. The patient had an ultrasound guided thoracentesis performed which led to an improvement of symptoms; 350 mL of fluid were taken removed, and chemistry showed a creatinine of 6.0, a pH of 7.36, an LDH of 190 and protein of 1.1, consistent with an exudative process. Of note, the patient’s serum creatinine was 1.10, serum protein was 6.5 and LDH was 111 that same day, making urinothorax a likely cause of the patient’s pleural effusion. A subsequent thoracocentesis was done to drain more fluid from his left pleural cavity. Fluid analysis still revealed an exudative process, but the creatinine of the pleural fluid was 0.7. Cultures of the pleural fluid were negative for an active bacterial or viral infection. The case was discussed with the urology and pulmonary team. He was managed conservatively since he did not have evidence of reaccumulation of fluid in the left pleural space. His shortness of breath, chest and flank pain resolved. He was weaned off supplemental oxygen and then discharged with outpatient urology follow–up.


Urinothorax is a medical condition in which urine fills the pleural space. The urine can move into the pleural space through an anatomical defect in the diaphragm or from the retroperitoneal space via the diaphragmatic lymphatics. It is a rare cause of pleural effusion, but appearance of a new unilateral pleural effusion after a recent urologic procedure should make it a consideration. The effusion is always on the side ipsilateral to the surgical site. Chemistry analyses of the pleural fluid that are consistent with urinothorax are low glucose, acidic pH and pleural fluid–to–serum creatinine ratio greater than one. In certain instances, like this one, a urinothorax can be managed conservatively after thoracentesis if further imaging does not show a re–accumulation of fluid. The persistence of a high creatinine level in subsequent fluid analyses is an indication that surgical intervention may be required. In these instances, surgical intervention is needed to correct defects causing the persistent fluid accumulation in the pleural cavity.


This case illustrates an unintentional development of urinothorax after an urologic procedure. Hospitalists need to be aware of this condition even as we are called upon to provide consult services and co–manage patients on other services.