Nephropleural Fistula
A nephropleural fistula — also called a reno-pleural or pyelopleural fistula — is an abnormal communication between the renal collecting system and the pleural space, producing a urinothorax. The most common cause is iatrogenic injury during supracostal percutaneous nephrolithotomy (PCNL); spontaneous fistulae arise from longstanding obstructive uropathy with forniceal rupture, and a third mechanism is penetrating thoracoabdominal trauma.[1][2] A pleural-fluid/serum creatinine ratio above 1 supports suspicion in the appropriate setting, but is not pathognomonic; establish a urinary source and interpret the fluid with the clinical and imaging findings.[10][1][3]
For operative selection, see the Fistula Repair (All Patients) database.
See also: The Kidneys, Fistulas landing page.
Etiology
The pleural reflection extends inferiorly along the posterior thoracic wall and crosses the 11th and 12th ribs, placing the upper-pole collecting system in close apposition to the pleural cavity. Any process that decompresses urine across this boundary can establish a fistula.
| Mechanism | Typical setting |
|---|---|
| Iatrogenic — supracostal PCNL | Higher supracostal access increases thoracic risk. In one series, nephropleural fistula occurred after 2/87 above-12th-rib tracts and 2/32 above-11th-rib tracts; these fistula rates should not be conflated with all pleural injuries[4][5][6] |
| Iatrogenic — other | Percutaneous nephrostomy, antegrade ureteroscopy, renal biopsy, ablation procedures[2] |
| Obstructive uropathy with forniceal rupture | UPJ obstruction, distal ureteral stone, pelvic malignancy compressing the ureter — urine decompresses retroperitoneally and tracks across the diaphragm into the pleural space (the classic spontaneous urinothorax)[1][7] |
| Penetrating or blunt thoracoabdominal trauma | Direct collecting-system injury with concurrent diaphragmatic disruption[2] |
| Renal / perirenal abscess | Erosion through Gerota's fascia and the diaphragm; xanthogranulomatous pyelonephritis is a recognized substrate[2] |
| Malignancy | Rare; renal cell carcinoma or urothelial carcinoma with diaphragmatic extension[2] |
Pathogenesis
The renal upper poles lie close to the diaphragm and pleural reflections; access trajectory and rib level influence the risk of thoracic injury.[5] When the pleural-renal communication is established, negative intrathoracic pressure during inspiration continuously aspirates urine across the defect, producing rapidly accumulating pleural effusion. If urine is sterile and the cavity is decompressed, the fistula will frequently close once the urinary tract is diverted; if urine is infected, the cavity becomes a urinary empyema with trapped lung.[2][5]
Clinical Presentation
Presentation is dictated by tempo and infection status:
- Acute post-PCNL — chest pain, dyspnea, falling oxygen saturation, or unexpectedly large output from a chest tube placed for routine pleural injury; output may be straw-colored urine rather than serous fluid.[5]
- Subacute / spontaneous — progressive pleuritic chest pain, dyspnea, and a large unilateral pleural effusion ipsilateral to obstructive uropathy or flank pain.[1][7]
- Infected — fever, leukocytosis, frank empyema, sepsis. Trapped lung and parapneumonic-pattern fluid in a patient with recent renal instrumentation should raise the diagnosis.
Hematuria, flank pain, decreased urine output, and a known stone or obstructive history are often present; the pleural effusion is typically massive and ipsilateral to the renal pathology.[1][7]
Evaluation
The diagnosis hinges on pleural-fluid biochemistry combined with imaging confirmation of the urinary source.
Thoracentesis and pleural-fluid analysis
| Finding | Interpretation |
|---|---|
| Pleural-fluid creatinine / serum creatinine ratio > 1.0 | Supportive in context, not independently diagnostic; values around 1 also occur in other effusions[10][1][3][8] |
| Low pH, low glucose | Variable; urinothorax is often transudative, but LDH-discordant or other exudative patterns occur. Neither Light's classification nor pH alone excludes it[2][3] |
| Urine-like odor and color | Supportive but neither sensitive nor specific |
| Positive culture | Implies urinary empyema; mandates source control |
Imaging
| Modality | Role |
|---|---|
| Chest radiograph | Initial detection of effusion; post-PCNL rib-level review for puncture height[5][9] |
| CT chest, abdomen, and pelvis with delayed urographic phase | Workhorse: demonstrates pleural fluid, the renal source (stone, obstruction, perinephric collection), and often the tract itself[2] |
| Antegrade or retrograde pyelography | Direct demonstration of contrast extravasation into the pleural space — most sensitive study when other imaging is equivocal[5] |
| Nephrostogram | Useful for follow-up confirmation of fistula closure before tube removal[5] |
| Pleural drainage with paired fluid/serum creatinine | Supports investigation of a recurrent effusion; confirm the urinary source rather than relying on the ratio alone |
Management
The cornerstone is proximal urinary diversion plus pleural drainage, with definitive treatment of the underlying obstruction or stone.[2][5]
Step 1 — control the pleural cavity
- Tube thoracostomy for symptomatic effusion, suspected empyema, or massive accumulation
- Repeated therapeutic thoracentesis for small, non-infected, slowly-accumulating effusions in selected patients
- VATS decortication for trapped lung or established empyema with pleural rind
Step 2 — divert the urinary tract
- Ureteral stent is the simplest first-line diversion when retrograde access is feasible[5]
- Percutaneous nephrostomy when retrograde access fails, when the upper tract is grossly dilated, or when a working access tract already exists from prior PCNL[2][5]
- Combined stent + nephrostomy for complex or proximal injuries
Step 3 — treat the underlying cause
- Complete clearance of any obstructing stone burden
- Pyeloplasty or endopyelotomy for UPJ obstruction
- Drainage and antibiotics for perirenal abscess
- Oncologic management for malignant erosion
Refractory or non-salvageable kidney
- Operative repair of the collecting-system defect — open or laparoscopic / robotic — is reserved for cases that fail prolonged diversion
- Partial or simple nephrectomy for a non-functional or destroyed pole / kidney with persistent fistula
- Diaphragmatic repair at the same setting if a discrete defect is identified
Most iatrogenic post-PCNL nephropleural fistulae resolve with the diversion-plus-drainage strategy alone; operative reconstruction is uncommon.[5]
Prevention
The most effective intervention is avoidance of supracostal access when subcostal access is feasible.[4][5] When supracostal access is required, end-expiratory puncture, minimizing tract dilation, intraoperative chest fluoroscopy and symptom-triggered postoperative imaging can help recognize pleural injury. Ogan’s prospective study did not support universal postoperative chest radiographs after negative intraoperative fluoroscopy; new respiratory symptoms still require prompt assessment.[5][9]
Outcomes
Early recognition, pleural drainage and urinary diversion often permit closure. In the cited four-case PCNL series, all fistulas had resolved by three months; one patient also required thoracoscopic decortication. Drain and stent removal should follow clinical and imaging confirmation rather than a universal healing deadline.[5] Delayed recognition with established empyema, persistent obstruction, or a nonfunctional kidney drives the small subset that requires operative repair or nephrectomy.
See Also
References
1. García-Pachón E, Padilla-Navas I. "Urinothorax: Case Report and Review of the Literature With Emphasis on Biochemical Diagnosis." Respiration. 2004;71(5):533–536. doi:10.1159/000080642
2. Toubes ME, Lama A, Ferreiro L, et al. "Urinothorax: A Systematic Review." J Thorac Dis. 2017;9(5):1209–1218. doi:10.21037/jtd.2017.04.22
3. Stark DD, Shanes JG, Baron RL, Koch DD. "Biochemical Features of Urinothorax." Arch Intern Med. 1982;142(8):1509–1511. doi:10.1001/archinte.1982.00340210101019
4. Munver R, Delvecchio FC, Newman GE, Preminger GM. "Critical Analysis of Supracostal Access for Percutaneous Renal Surgery." J Urol. 2001;166(4):1242–1246. doi:10.1016/s0022-5347(05)65750-9
5. Lallas CD, Delvecchio FC, Evans BR, Silverstein AD, Preminger GM, Auge BK. "Management of Nephropleural Fistula After Supracostal Percutaneous Nephrolithotomy." Urology. 2004;64(2):241–245. doi:10.1016/j.urology.2004.03.031
6. Hopper KD, Yakes WF. "The Posterior Intercostal Approach for Percutaneous Renal Procedures: Risk of Puncturing the Lung, Spleen, and Liver as Determined by CT." AJR Am J Roentgenol. 1990;154(1):115–117. doi:10.2214/ajr.154.1.2104692
7. Salcedo JR. "Urinothorax: Report of 4 Cases and Review of the Literature." J Urol. 1986;135(4):805–808. doi:10.1016/s0022-5347(17)45855-7
8. Salyer WR, Eggleston JC, Erozan YS. "Urinothorax: An Unusual Cause of Pleural Effusion." JAMA. 1971;218(11):1683–1684. doi:10.1001/jama.1971.03190240037008
9. Ogan K, Corwin TS, Smith T, et al. "Sensitivity of Chest Fluoroscopy Compared With Chest CT and Chest Radiography for Diagnosing Hydropneumothorax in Association With Percutaneous Nephrostolithotomy." Urology. 2003;62(6):988–992. doi:10.1016/j.urology.2003.07.024
10. Shayani KE, Schwartz J, Oslance N, et al. Urinothorax and pleural fluid creatinine: a retrospective analysis of pleural fluid studies at a tertiary care center and a review of the literature. J Thorac Dis. 2025;17:9357–9363. doi:10.21037/jtd-2025-879