Nephropleural fistula after supracostal approach for PCNL: report of two cases with review of literature

Abstract

Nephropleural fistula is a rarely encountered complication of percutaneous nephrolithotomy (PCNL). Only 11 cases have been reported in literature to date. Often associated with supracostal punctures, the presentation is frequently delayed. Diagnosis is based on imaging, mainly X-rays and CT along with retrograde pyelography that establishes the fistulous connection. A difficult to diagnose condition, any patient with a supracostal access PCNL who presents with delayed symptoms of breathlessness and has leucocytosis with fluid in the lungs on chest imaging should be suspected to have a nephropleural fistula. The management involves intercostal tube thoracostomy to relieve symptoms and drainage of the operated kidney by double-J stent placement, if not placed already. Prompt recognition and management results in excellent recovery with no sequelae. We present our experience with two such cases and our aim was to familiarise the practising urologist regarding the diagnosis and management of this infrequent condition.

Background

The posterior intercostal approach has been commonly used to gain access for percutaneous nephrolithotomies (PCNL). The intercostal approach is more commonly through the 11th intercostal space (ICS) and less commonly through the 10th ICS. Also called the supracostal approach, it is considered to be associated with a higher risk of thoracic complications. The complications related with this approach include injury to lungs, pleura, liver and spleen. Delayed nephropleural fistula is a very rare complication of this approach. A total of 2079 PCNLs were performed by a single surgeon (HNS) between April 2003 and March 2017, and 998 patients required a supracostal approach, of whom 209 needed the 10th ICS approach due to the location of the stones and the anatomy. Two patients were diagnosed to have iatrogenic delayed nephropleural fistula in this cohort. We describe these two cases of rare complications associated with our PCNL experience and reviewed available literature to determine risk factors, appropriate management and possible ways to prevent it with the aim of acquainting the practising urologist with a diagnostic as well as a rational management plan for the condition.

Case presentation

Case report 1

A 70-year-old female patient underwent left PCNL with placement of percutaneous nephrostomy (PCN) (PCN tube) and ureteral stent for 2.5 cm upper calyceal stone via the supracostal (10th ICS) approach. She was confirmed to be stone-free on the first postoperative day (POD) on X-ray kidney–ureter–bladder (KUB). Her chest X-ray (CXR) was normal and serum creatinine was 0.9 mg/dL. She was discharged on the first POD after removal of PCN and a voiding trial, but was readmitted 2 days after discharge, through the emergency with complaints of severe breathlessness and left-sided chest and shoulder pain. Clinical examination revealed reduced air entry on the left side of the chest with normal saturation levels.

Based on the supracostal access and ipsilateral pleural effusion producing breathlessness, a working diagnosis of pleural violation leading to effusion was made and appropriate investigations were initiated after counselling the patient regarding the differential diagnoses.

Case report 2

A 40-year-old male patient presented with fever of 2 days duration and breathlessness for a duration of 1-day postbilateral simultaneous tubeless PCNL performed 12 days prior. He had a large 3.5 cm right renal pelvic stone and left 2.5 cm partial staghorn stone. The supracostal approach to PCNL was needed on both sides as the kidneys were high-lying. On the first POD, X-ray KUB confirmed stone-free status and CXR was normal (figure 1A). Patient had ureteral stent placed bilaterally with string which was removed 1 week after surgery.

Figure 1.

Pretreatment and post-treatment images. (A) Postoperative CXR on day 1. (B) Post-readmission CXR. (C) Postintercostal drainage CXR. CXR, chest X-ray.

After readmission 4 days post ureteral stent removal, auscultation revealed significantly reduced air entry on the right side. Saturation levels were normal. Similar to the prior case, a suspicion of pleural effusion secondary to pleural violation was made and investigations were initiated.

Investigations

Case report 1

CXR disclosed left pleural effusion. Serum creatinine was elevated to 1.7 mg/dL and leucocyte count was 12 100/mm³. Pleural fluid aspirate revealed creatinine levels similar to urine levels.

Case report 2

CXR revealed right-sided moderate pleural effusion. Blood investigations showed an elevated leucocyte count to 11 800/mm³ and serum creatinine to 1.8 mg/dL, which continued to rise despite initial treatment. Retrograde pyelogram (RGP) performed at the time of ureteric stenting at a slightly later time clearly revealed the communication of the fistula between the operated kidney and the lung.

In both patients, immediate postoperative CXR on the first POD did not show any evidence of pleural effusion and X-rays done on readmission 3 and 12 days post PCNL showed evidence of effusion with high fluid creatinine confirming diagnosis of nephropleural fistula. There was no evidence of pulmonary consolidation in both the cases to suggest a parapneumonic cause of pleural effusion.

Differential diagnosis

In both the cases, the clinical condition at presentation and the initial diagnostic tests of CXR that revealed pleural effusion and elevated leucocyte counts with azotemia pointed to a possible diagnosis of pleural violation with resulting effusion. The raised serum creatinine could possibly have resulted due to prerenal or renal causes of acute kidney injury. Obstruction of the kidneys resulting in acute kidney injury were unlikely as per our assessment, a stone-free status had been confirmed and the contralateral kidney had normal renal function.

Another differential diagnosis that we had in mind was parapneumonic effusion secondary to lung atelectasis especially considering the high access for both the procedures.

However, in view of the raised pleural fluid creatinine and delayed presentation with stone-free status, the evidence of nephropleural fistula was overwhelming.

Treatment if relevant

Case report 1

Based on the clinical condition and the investigations, an immediate drainage of the effusion and decompression of the kidney was planned. She underwent placement of Foley catheter to minimise ureteral stent-related urine reflux and placement of left intercostal drain (ICD) under ultrasound guidance with placement of 12 Fr pigtail catheter. One and a half litres of serosanguinous fluid was drained, and pleural fluid creatinine was sent for which was found to be similar to urine creatinine. The patient was initiated on intensive chest spirometry and chest physiotherapy. The ICD was clamped after 2 days when CXR showed complete drainage of fluid and creatinine reduced to 1.1 mg/dL. Repeat CXR a day after clamping the ICD did not reveal any recurrence of effusion. On the fourth day, both Foley catheter and ICD were removed with a normal CXR the following day. The patient was discharged on the fifth day in a completely asymptomatic condition. At 1 month postsurgery, left double-J (DJ) stent removal was performed in the clinic after confirming stone-free status on X-ray KUB and renal ultrasound.

Case report 2

Since the patient was stable and the effusion was moderate, conservative treatment with intravenous broad-spectrum antibiotics, chest physiotherapy and nebulisation for 2 days was initiated. A right-sided pleural tap was performed under ultrasound guidance and 300 mL of serosanguinous fluid was aspirated. However, the patient’s condition was unchanged with persistence of breathlessness and further rise in creatinine to 2.1 mg/dL. The pleural fluid creatinine was highly suggestive of urine. A repeat CXR revealed an increase in the size of the effusion as compared with the previous radiograph on readmission (figure 1B). He underwent right RGP, which revealed nephropleural fistula with no evidence of any ureteric obstruction (figure 2) and a ureteral stent was placed. He also had a 12 Fr pigtail catheter placed in the pleura under ultrasound guidance as an ICD and 750 cc of straw-coloured fluid was drained. At the end of the procedure, a Foley catheter was also placed. The patient’s condition improved over the next 2 days. Serial radiographs also were suggestive of significant reduction in the effusion (figure 1C) and serum creatinine was 1.1 mg/dL. The patient’s ICD was clamped on the third day, and repeat CXR on the fourth day did not reveal any further deterioration. Both his ICD and the Foley catheter were removed the next day and he was discharged home with advice to continue chest spirometry. He returned back after 3 weeks for removal of the right ureteral stent. CXR at that time was normal.

Figure 2.

Retrograde pyelogram demonstrating nephropleural fistula.

Outcome and follow-up

Both patients did extremely well with complete resolution in clinical as well as radiological parameters. Their follow-up in clinic was after 3–4 weeks when they underwent removal of the ureteric stents. There was no recurrence of symptoms after stent removal that substantiated the total obliteration of the fistula.

Both patients were asymptomatic and reported to be back to their activities of daily living at 6-month follow-up.

Discussion

PCNL has become the primary surgical treatment for large or complex renal calculi in the last two to three decades.¹ Despite the proven efficacy, PCNL is not immune to complications, some of which can be life threatening.² Upper pole or complex stone burdens including partial and complete staghorn calculi at times need placement of percutaneous tract through an upper pole calyx to ensure good access to the targeted stone. The main advantage of the supracostal upper pole access is that the line of puncture directly aligns with the renal pelvis, resulting in excellent clearance of stones in the upper calyx, renal pelvis and lower calyces.³ A supracostal access, however, results in a higher risk of pulmonary complications due to violation of the pleura.^{4 5} Pulmonary complications of PCNL include hydrothorax, hemothorax, hydropneumothorax and pleural effusions.^{6 7}

The posterior reflection of pleura extends inferiorly to the 12th rib, and the lowermost part of the lung edge lies above the 11th rib in the 10th ICS. During full expiration, 80%–85% of the upper pole is aligned above the 12th rib, and at the end of expiration, in the supracostal approach, the pleura is traversed on the right in 29% of cases and on the left in 14%.⁸ The risk of pleural injury is greatest during the inspiratory phase of respiration. General anaesthesia is thus needed to control respiratory movements during puncture and to access the path with least chances of pleural or pulmonary complications. For supracostal access, the puncture site should be made in the upper portion of the ICS, just lateral to the paraspinal muscles, and puncture above the 11th rib should be avoided unless necessary. At times, the upper pole can be approached via a laterally situated tract between the tips of the 11th and 12th ribs or even by a subcoastal approach. The use of Amplatz working sheath is mandatory in patients with supracostal approach to decrease the risk of hydrothorax.

One of the rare complications observed with the supracostal approach is the nephropleural fistula, which is a persistent communication between the renal collecting system and the thoracic cavity.⁹ There are only 11 such cases reported in English literature to date (table 1).

Table 1.

Review of literature on published case reports on nephropleural fistula after PCNL

Serial no.	Author, year of publication	Patients (n)	Type of stone for which PCNL was performed	Location of access and duration of presentation after PCNL (days)	Treatment of nephropleural fistula
1	Lallas et al, 20049	4 (only 2 patients described)	1.5 cm L UC stone	Supra 11th rib 2 days	ICD and thoracoscopic decortication for loculated effusion
			3 cm R RP stone+multiple stones in proximal ureter and LC	Supra 12th rib 2 days	ICD+PCN+DJ stent+Foley catheter
2	Kaler et al, 201616	1	Partial R staghorn 5.9 cm with large parapelvic cyst	Supra 11th rib 7–8 days	ICD+bilateral PCN+removal of migrated left upper ureteric calculus+Foley catheter
3	Baugh et al, 201618	1	Partial R staghorn 2.1 cm+left 1 cm LC stone	Supra 12th rib 5 days	Serial thoracocentesis+right DJ stenting+Foley catheterisation
4	Hyatt et al, 201711	1	R upper pole calyceal diverticulum	Supra 10th rib Recurrent effusion	Repeat ICD placement
5	Chawla and Karimi, 202020	1	R 8 mm upper ureteric stone	Access NS 2 days	VATS+hemothorax evacuation+ICD
6	Arora et al, 201521	1	R partial staghorn	Supracostal NS days	ICD+PCN in lower pole+repositioning of DJ stent
7	Agranovich et al, 200812	1	L complete staghorn	Access NS 21 days	NS
8	Price et al, 202017	1	L complete staghorn+ureteral stone	Access NS 4 days	DJ stenting+horacocentesis and removal of residual left ureteric calculi+ICD
9	Present series	2	2.5 cm UC	Supra 10th rib 2 days	ICD+Foley+respiratory treatment
			3.5 cm R RP and L 2.5 cm partial staghorn	Supra 11th 12 days	ICD+Foley+respiratory treatment

DJ, double-J; ICD, intercostal drain; L, left; LC, lower calyx; NS, not specified; PCN, percutaneous nephrostomy; R, right; RP, renal pelvis; UC, upper calyx; VATS, video-assisted thoracoscopic surgery.

DJ, double-J; ICD, intercostal drain; L, left; L, left; LC, lower calyx; NS, not specified; PCN, percutaneous nephrostomy; PCNL, percutaneous nephrolithotomy; R, right; RP, renal pelvis; UC, upper calyx; VATS, video-assisted thoracoscopic surgery.

The presentation of these fistulae is variable and can occur 1–2 weeks post-PCNL. Although many studies in literature have quoted an early presentation ranging from immediate postoperative¹⁰ to early postoperative period ranging from 2 to 5 days,^{9 11} some fistulae may present in a delayed fashion up to 3 weeks, which may contribute to difficulties in diagnosis.¹² Persistent slow leakage of both fluid and urine into the thoracic cavity may result in pleural effusion and respiratory compromise.¹³ The diagnosis should be considered in the list of differentials for any patient who has undergone PCNL by supracostal approach and who presents with sudden-onset breathlessness with/without flank or chest pain. The quoted literature shows that most patients presented with breathlessness and some could present with associated fever and elevated leucocyte counts. Since the left kidney lies at a higher level, the index of suspicion should be greater for supracostal punctures on this side.

Owing to its rarity, a critical index of suspicion is required to suspect a possible nephropleural fistula. After an initial CXR or chest CT performed for the usual presentation of breathlessness, the diagnosis of nephropleural fistula is best made by retrograde pyelography to demonstrate the fistulous communication (figure 1C). The abnormality of postoperative chest radiographs depends on the volume of pleural effusion. The appearance of a meniscus in the posterior costophrenic sulcus on an upright CXR and the posteroanterior view determined that the pleural fluid was 50 and 200 mL, respectively. The amount of pleural fluid that obliterates the hemidiaphragm is about 500 mL.¹⁴ Routine postoperative radiograph of the chest is recommended for evaluation of the chest after an upper pole approach. Ogan et al reported the sensitivity in the detection of pleural fluid after PCNL by intraoperative chest fluoroscopy with immediate postoperative chest films and CT on POD 1 in 100 renal units of 89 patients.¹⁵ This technique is advantageous because it allows the aspiration of pleural fluid while the patient is still under anaesthesia. If the intraoperative fluoroscopy is normal, a formal chest radiograph is recommended only if the patient is symptomatic. The sensitivities of initial fluoroscopy, immediate postoperative radiography and chest CT scan were 1%, 8% and 38%, respectively. However, one must keep in mind the delayed appearance of these fistulae, which may contribute to false-negative intraoperative/postoperative chest imaging. Both of our patients also had elevated serum creatinine level on presentation. We hypothesised that the absorption of urine from the pleural cavity might cause false elevation of serum creatinine despite normal renal function. Once the urinothorax was drained, the serum creatinine promptly returned to normal baseline level.

Other than the slow and continuous accumulation of fluid, an additional precipitating event that may be responsible for these fistulae manifestations to manifest after many days is an acute obstructive event like a clot or stone fragments. This was reported by Kaler et al, wherein fragments of calculi had obstructed the upper ureter, which had to be removed ureteroscopically followed by DJ stenting for optimal drainage for symptoms to resolve.¹⁶ A similar scenario was presented in two other case reports with the first reporting an obstructing stone in the ureteropelvic junction and a displaced DJ stent with a delayed nephropleural fistula¹² and the other reporting multiple upper ureteric calculi.¹⁷ Prompt recognition and management of obstruction is key before appropriate decompression, which usually leads to an early and uneventful recovery in most cases. None of our patients had evidence of ureteric obstruction; in fact, one patient already had indwelling ureteral stent after PCNL.

Regardless of the timing, once a nephropleural fistula has been identified, prompt intervention to decompress the collecting system and drainage of the effusion have to be taken, addressing the pneumothorax concomitantly. As the patient is usually symptomatic with breathlessness, thoracocentesis (ultrasound or fluoroscopic) brings prompt relief, but an ICD maintained in situ for a few days treats the situation most effectively. Both our patients had excellent symptom relief with ICD drainage. Serial thoracocentesis has been reported for pleural effusion with good results,¹⁸ but prompt ICD drainage in case of failure must be instituted.¹⁷ An indwelling DJ stent leads to fistulous tract closure by improving drainage and bypassing the obstruction.¹⁹ Most cases do require decompression with a PCN and a Foley catheter as decompression with purely a stent may be insufficient. In both our cases, DJ stent usage was sufficient for internal drainage. Finally, more aggressive treatment, such as decortication or pleural sclerosis especially using video-assisted thoracoscopic surgery may be necessary for persistent or worsening intrathoracic fluid/blood despite ICD placement or worsening clinical condition and collecting system decompression, and therefore early and effective communication with the thoracic surgery team is essential.²⁰

Lallas et al in their series noted that one of the techniques to prevent nephropleural fistulae is to remove all tubes from the upper pole access site and to place them in a remote lower pole location.⁹ Nephrostogram prior to removal of the nephrostomy tube may help in diagnosing nephropleural fistula; however, the reduction in the incidence of nephropleural fistula is debatable.⁹ The second patient in our series had tubeless PCNL and developed urinothorax after the indwelling ureteral stent was removed at 1 week after surgery.

In conclusion, we recommend getting a routine postoperative CXR prior to discharge for all supracostal access PCNLs as an ipsilateral pleural effusion could be a sign of nephropleural fistula. All patients undergoing PCNL with supracostal access should be counselled about a possibility of a delayed nephropleural fistula. Any symptoms of delayed breathlessness should be similarly dealt with caution with both chest and abdominal imaging to note effusion, if any, stent position and any stone fragments. Management with ICD with respiratory therapy for moderate to large effusions after RGP confirmation of fistulae with appropriate drainage with DJ stenting and PCN usually results in excellent outcomes.

Patient perspective.

Patient 1: ‘I was extremely satisfied with my surgery for left kidney stone and was concerned when I experienced breathlessness after a couple of days at home. I was told in the ER that there was significant fluid in my lungs and I was informed that there was a possibility that this was a complication due to the surgery itself. I felt significant relief when the fluid was removed and a tube was placed in my chest. I improved and was discharged after tube removal. I restarted my work after 2 weeks and stent was removed after 6 weeks. I was told that I had a rare complication after surgery and am happy to participate in the study to help other doctors and patients’.

Patient 2: ‘Twelve days after surgery, I had progressively severe breathlessness. In the ER, they told me about fluid in the right side of the chest. The doctors placed a tube in my chest and bladder and started physiotherapy. I felt a lot of relief and was discharged home after few days. I was back to work in 2 weeks and thank the team of doctors to have taken care of me’.

Learning points.

• Nephropleural fistula is a rare complication of supracostal access percutaneous nephrolithotomy (PCNL) that requires a high index of suspicion for diagnosis, especially in those cases where the diagnosis is delayed.

• Any patient who has undergone supracostal access PCNL and presents with breathlessness should be evaluated with a prompt chest X-ray and basic blood parameters and stabilised with supportive measures.

• The management of effusion usually requires pleural aspiration and intercostal drainage in the majority of patients. The decompression of the operated kidney with measures such as stenting and percutaneous nephrostomy tube is essential for closure of the fistulous connection.

• Effective communication with the thoracic surgery team ensures a prompt intervention especially in those cases where surgical interventions are needed.