Case Presentation: An 80-year-old Caucasian male with a history of recently diagnosed transitional cell carcinoma, diastolic heart failure (EF 65%), BPH, and CKD stage III presented with dysuria, hematuria, fever, and dyspnea one-month after cystoscopy with left ureteral stent exchange and palliative laser ablations of his ureteral and bladder lesions. Chest radiograph and CT abdomen and pelvis showed bilateral pleural effusions, left hydroureteronephrosis without stone, and a 10.4cm cystic lesion of his left kidney that increased in size compared to a previous study. Echocardiogram showed only known mild diastolic dysfunction. He subsequently underwent right thoracentesis removing 1.2L of serous fluid. Fluid pH was 1.0 and was otherwise consistent with a transudative process. During his hospitalization, he underwent a repeat cystoscopy, left stent placement x2, and TURBT. Postoperatively, the patient’s respiratory status worsened again requiring supplemental oxygen. Repeat CXR and CT chest showed recurrence of pleural effusion. Repeat thoracentesis removed 1.2L of yellow fluid. Fluid studies showed a transudative process, leukocytosis, pH 1.4, BUN 55, Cr of 2.0 (serum Cr 2.1). Following the thoracentesis, his respiratory status improved, and the effusion has not reaccumulated.
Discussion: Most pleural effusions arise from cardiac, hepatic, pulmonary, malignant, or infectious causes. However, this case illustrates the importance of recognizing pleural effusions of extravascular origin (PEEVO). PEEVO can occur from migration of fluid from CNS, abdominal, or genitourinary sources. An injury to the urinary system can cause urine to propagate into the retroperitoneal or perineal space, forming a urinoma. Then, by transdiaphragmatic migration via lymphatic vessels or diaphragmatic pores into the pleural cavity, urinothorax is formed. Urinothorax is most associated with an obstructive uropathy from nephrolithiasis or extrinsic tumor, or less commonly from surgical manipulation. This case describes the importance of recognizing PEEVO, specifically urinothorax, by careful examination of the clinical context.
Conclusions: Urinothorax usually presents on the side of obstruction and is often unilateral, although bilateral cases have been reported, as in our patient. Characteristically, it is a transudative process, with a pH<1.4. Diagnostic criteria for urinothorax include a pleural fluid/serum creatinine ratio>1, pH<1.4, or a technitium-99 renal scan. Although no fluid Cr level was obtained initially, the combination of pH 1.0 initially and PF:S Cr 0.95 with pH 1.4 later suggests urinothorax. Furthermore, his clinical context was suggestive as he presented with urinary obstruction and has not had subsequent reaccumulation of pleural effusion. Pleural effusions are commonly encountered in hospitalized patients and most commonly present due to CHF exacerbation or infection. However, urinothorax is a rare complication and likely underrecognized in hospitalized patients with obstructive stones and prior cystoscopic manipulation, thereby demonstrating the importance of keeping a high suspicion in the right clinical context when differentiating the causes of pleural effusion.