Percutaneous Removal of Retained Metallic Ureteral Stent with a Looped Polytetrafluoroethylene-Coated Guidewire

Abstract

Background: Ureteral stricture disease is a troubling urologic issue that can be managed with surgical reconstruction or, more conservatively, with chronic nephrostomy tubes or ureteral stents. These indwelling tubes require exchanges and are prone to complications such as encrustation or stent failure. Metallic ureteral stents are designed to be more resistant to extrinsic compression and allow for exchanges at longer intervals. However, encrustation or tissue ingrowth can occur with these stents as well. The removal of encrusted or embedded metallic ureteral stents poses a difficult clinical scenario. We present a case of an encrusted metallic stent embedded in a proximal ureteral stricture requiring percutaneous endoscopic removal with a novel looped-wire technique.

Case Presentation: A 50-year-old Caucasian man with bilateral ureteral stricture disease, managed with chronic indwelling metallic stents, failed retrograde removal on the right during routine exchange. Staged procedures with percutaneous nephrostomy, followed by combined percutaneous antegrade and retrograde endoscopy were required to observe and access the embedded stent. The exposed metallic surface was unable to be grasped by available instruments through flexible endoscopy. Under endoscopic control with fluoroscopic guidance, a polytetrafluoroethylene (PTFE)-coated guidewire was looped around the metallic stent. With gentle traction on the wire loop, the embedded stent curl was delivered out of the stricture and into the renal pelvis from where it was extracted carefully with graspers inserted through a rigid nephroscope. Follow-up antegrade fluoroscopic studies with contrast showed no extravasation.

Conclusion: Percutaneous removal of metallic stents retained within the ureter has unique challenges. We present a novel method of extraction of a retained metallic stent with a looped PTFE-coated guidewire, which may safely and effectively be used in complex situations.

Introduction and Background

Ureteral stricture disease is a potential complication after endoscopic intervention for nephrolithiasis. Patients who are poor surgical candidates for definitive reconstruction are often managed with nephrostomy tubes or ureteral stents that are exchanged at scheduled intervals. Stent failure or encrustation can occur and may require retrograde and/or antegrade intervention depending on patient anatomy and the location of stent encrustation. For stents that become encrusted or embedded in the setting of ureteral stricture disease, removal may be complicated. Endoscopic techniques include removal with a basket, grasping forceps, or a snare device. Ureteroscopy may be necessary for retrograde retrieval of an encrusted or embedded stent as well. Ureteroscopic techniques generally require exposure of either the proximal or distal stent tip to achieve a reliable grasp on the stent to allow for extraction. Percutaneous endoscopic removal may be required for heavily encrusted polymer stents, especially with proximal curl involvement. Combined antegrade and retrograde approaches may also be required. If endoscopic options fail, open surgical intervention must be considered.

Metallic stents are designed to be more resistant to extrinsic compression and may decrease encrustation.¹ These factors allow for time intervals between stent exchanges to be extended, decreasing associated procedural risks. Exchanges are often performed effectively despite significant ureteral stricture disease. Although rare, metallic ureteral stents may still be at risk for encrustation.¹ These stents are also at risk for tissue ingrowth, which can result in embedment of the stent in the ureteral stricture. Although there is ample literature regarding removal of encrusted or retained polymer stents, limited data exist on removal of encrusted or embedded metallic ureteral stents. We present a case of an encrusted metallic stent embedded in a proximal ureteral stricture requiring percutaneous endoscopic removal with a novel looped-wire technique.

Presentation of Case

A 50-year-old Caucasian man with a history of Ehlers Danlos Syndrome and nephrolithiasis developed bilateral ureteral strictures after multiple endoscopic interventions. Owing to medical comorbidities limiting candidacy for extensive surgical reconstruction, he was dependent on intermittent stent exchanges. He was converted to Resonance^® metallic stents (Cook Medical LLC, Bloomington, IN) in 2017 secondary to rapid encrustation of his polymer stents within a 3-month interval. Past history was also notable for recurrent urinary infections with multiple episodes of fungemia. He had done well with metallic stent exchanges every 6 months leading up to his most recent stent exchange. During exchange, minimal stone encrustation was noted on the distal curl through cystoscopy, and alligator graspers were used to attempt retrograde removal under fluoroscopic guidance. Resistance was met as the stent moved from the renal pelvis into the proximal ureter, and the proximal curl of the stent did not unfurl after encountering an area of known proximal ureteral stricture. A Bentson wire was able to pass to the level of the kidney adjacent to the retained stent. Retrograde pyelography confirmed placement of the wire into the renal pelvis.

To further investigate the stent, ureteroscopy was performed and was notable for stone debris along the shaft of the stent. Laser lithotripsy was required to navigate adjacent to the stent in clearing small volume of calcification to allow for more working space given a narrowed distal lumen. The flexible ureteroscope was unable to advance past the level of the iliac vessels because of dense stricture disease. A ureteral balloon dilator was unable to expand the dense stricture. Ultimately a 4.8F stent was placed next to the metallic stent for temporary decompression before nephrostomy tube insertion and attempt at percutaneous stent removal.

At the time of elective percutaneous ureteral stent removal, access was obtained through a posterior upper pole calix through balloon dilation and placement of an access sheath. Flexible ureteroscopy was performed into the dilated proximal ureter. Dense stricture was noted roughly 3 cm distal to the level of the ureteropelvic junction (UPJ). Minimal stone encrustation was noted on the proximal stent, and a flexible ureteroscope with a 200 μm holmium–yttrium-aluminum-garnet (Ho:YAG) laser fiber was used to clear off all stone debris. There was no sign of high-volume stone encrustration at the actual proximal curl, and the limitation of retrograde removal appeared to be the location lodged into a dense proximal stricture.

Once the stone material was cleared, the ureteroscope was able to advance beyond the level of the stricture. With ureteroscope deflection, the stent tip was seen embedded in the lateral aspect of the ureteral stricture (Fig. 1). Antegrade injection of contrast revealed no extravasation at the site of the embedded stent (Fig. 2). Ureteroscopic graspers were too small to engage the body of the metallic stent. Both a snare device and a 1.9F nitinol stone basket could not grasp the stent tip because of its embedded location in the stricture. The rigid nephroscope and flexible cystoscope could not traverse the UPJ, thus limiting the platform available for more rigid grasping forceps.

FIG. 1.

Initial antegrade ureteroscopic view of stent tip in strictured flap of the proximal ureter, with 5F ureteral catheter positioned from retrograde approach and Amplatz wires through the percutaneous access into the bladder.

FIG. 2.

Initial right antegrade nephrostogram revealing beginning location of metallic stent in the left proximal ureter, with retrograde 5F ureteral catheter positioned in the renal pelvis.

At that time, we theorized the use of a wire looped around the proximal stent curl as an extraction device. A Bentson wire was placed through the ureteroscope with the distal tip of the wire adjacent to the proximal stent curl. Next, the stone basket was advanced along the opposite side of the stent and was used to grasp the tip of the Bentson wire underneath the proximal curl of the stent. This allowed the formation of a loop around the stent at the apex of the proximal curl (Fig. 3). The distal end of the wire was then externalized through the percutaneous access sheath. Once both sides of the wire were excluded from the ureteroscope and secured externally as one unit, gentle traction was placed on the looped wire under live fluoroscopy and direct ureteroscopic observation. This technique delivered the proximal stent curl out of the stricture and into the renal pelvis (Fig. 4). The rigid nephroscope was then used to remove the stent through the percutaneous tract with rigid graspers.

FIG. 3.

Antegrade ureteroscopic view of embedded metallic stent in strictured tissue flap in the proximal ureter, with looped PTFE wire passed distal to the stent and externalized out of the percutaneous access sheath. PTFE, polytetrafluoroethylene.

FIG. 4.

Metallic stent repositioned into renal pelvis after traction placed on externalized ends of PTFE wire through the percutaneous access sheath. Flexible cystoscopy performed, as seen through the access tract confirmed intrapelvic location before removal with rigid nephroscopy and graspers.

Antegrade injection of contrast revealed no extravasation at the point of previous ureteral embedment, and antegrade flexible ureteroscopy cleared the ureter of any residual stone debris. No areas of ureteral injury were identified. A 6F polymeric ureteral stent was placed in standard antegrade manner with fluoroscopic guidance. The previously placed nephrostomy tube was removed. A 16F Council tip catheter was placed through the percutaneous access site as nephrostomy tube to optimize drainage while the patient remained on intravenous antimicrobials given his infectious history. His nephrostomy tube was removed on postoperative day one and he was discharged home after completion of perioperative antimicrobials. The patient was scheduled for his next stent exchange in approximately 2 months.

Discussion and Literature Review

Metallic ureteral stents are designed to resist extrinsic compression and are often used in patients with terminal conditions or dense ureteral stricture disease.² Alternatives include tandem polymeric ureteral stents or metal-mesh stents, with the quality of evidence limited on the optimal strategy for these conditions.² There is a paucity of data in the literature describing encrustation or retention of these stents. Kawahara et al. reported effective retrograde removal of an encrusted metallic ureteral stent using a disposable ureteroscope with Ho:YAG laser lithotripsy to break the encrustation along the body of the stent.³ After removal, they performed extracorporeal laser fragmentation of the metallic stent itself and noted that it easily fragmented at a setting of 2.0 J, 5 Hz.³ In contrast to the laser fragmentation of polymeric stents, lasering of the metallic interface may theoretically produce sharp fragments capable of tissue damage. Rare descriptions exist of percutaneous removal of encrusted or retained metallic ureteral stents.¹ In comparison, percutaneous removal of encrusted polymer stents is typically performed for high-volume stent encrustation and adherent stone matter. Pais et al. described this technique in a multicenter review confirming percutaneous nephrolithotomy as a safe and effective technique for addressing retained encrusted polymer stents.⁴

Owing to the rigidity of the metallic stent, the most commonly used techniques for removal of retained polymer stents were not effective in removal of the retained metallic stent. Theoretically, the metal-on-metal interface is less deformable when compared with the metal-on-polymer interface encountered when grasping a polymer stent with rigid graspers, making removal more difficult. The looped-wire technique described in this report may allow for effective manipulation of encrusted or embedded polymer or metallic stents and avoid the need for more invasive surgical removal. By accessing the proximal stent curl and repositioning it into a more favorable location, this technique allows more reliable platform for definitive stent removal. Although not previously described, this technique may add to the endoscopic armamentarium by utilizing common tools to deal with the unique challenge presented by retained ureteral stents.

Conclusion

Metallic ureteral stents can become encrusted or embedded in ureteral tissue because of adherent calcification or dense stricture disease. A polytetrafluoroethylene-coated guidewire looped around the proximal curl of the stent can safely deliver the stent into a favorable position for basket, snare, or grasper removal. This may allow for the avoidance of more invasive interventions in a complex patient population.

Abbreviations Used

Ho:YAG

holmium–yttrium-aluminum-garnet

PTFE

polytetrafluoroethylene

UPJ

ureteropelvic junction

Disclosure Statement

J.G.P., A.K.R., A.O.G., and J.K. acknowledge no competing financial interests exist. V.G.B. serves as a consultant for Boston Scientific.

Funding Information

No funding was received for this article.

Cite this article as: Pavlinec JG, Rabley AK, Gordon AO, Kuo J, Bird VG (2020) Percutaneous removal of retained metallic ureteral stent with a looped polytetrafluoroethylene-coated guidewire, Journal of Endourology Case Reports 6:4, 328–331, DOI: 10.1089/cren.2020.0115.