Original Research
JOURNAL OF ENDOUROLOGY Volume XX, Number XX, XXXXXX 2014 ª Mary Ann Liebert, Inc. Pp. ---–--DOI: 10.1089/end.2014.0004
Percutaneous Nephrolithotomy for Removal of Encrusted Ureteral Stents: A Multicenter Study Vernon M. Pais, Jr., MD,1 Ben Chew, MD,2 Ojas Shaw, MD,3 Elias S. Hyams, MD,1 Brian Matlaga, MD,4 Ramakrishna Venkatesh, MBBS,5 Jay Page, MD,5 Ryan F. Paterson, MD,2 Olga Arsovska, BSc,2 Michael Kurtz, MD,6 and Brian H. Eisner, MD6
Abstract
Purpose: Encrusted ureteral stents are a challenging endourologic problem. We performed a multi-institutional review of percutaneous nephrolithotomy (PCNL) as primary treatment for encrusted stents. Materials and Methods: We identified 36 patients who underwent PCNL for treatment of an encrusted stent. A retrospective review was performed to compile details of procedures and outcomes for these patients. Results: In 36 patients, 38 renal units underwent PCNL for encrusted ureteral stents. The mean patient age was 47.1 years ( – 16.7), and the female:male ratio was 15:21. Mean stent indwelling time before removal was 28.2 months ( – 27.8). The reason for long indwelling time was reported in 25 cases; these reasons included ‘‘patient unaware stent needed to be removed’’ (17 cases), pregnancy (2 cases), other comorbidities (3 cases), and patient incarceration (3 cases). In 3 cases, the stent had become encrusted within 3 months of placement. Mean operative time was 162 minutes ( – 71). There were no major intraoperative complications, and no patients required blood transfusion. Litholapaxy was required for bladder coil encrustations in 22 cases (58%), and ureteroscopy with lithotripsy was required for encrustation of the ureteral portion of the stent in 13 cases (34.2%). Second look percutaneous procedures were required in 13 cases (34.2%). The stent was removed at the time of PCNL without need for concomitant or delayed ureteroscopy and/or cystolitholapaxy in 8 cases (21%). Ultimately, all stents were removed successfully. Patients were rendered stone free according to radiographs in 24 cases (63%). Conclusions: In this multicenter review, PCNL is confirmed to be a safe and effective means of addressing the retained and encrusted ureteral stent. PCNL without ureteroscopy or litholapaxy was sufficient in a minority of cases (21%). Adjunctive endourologic modalities are often required, and the surgeon should anticipate the need for concomitant antegrade ureteroscopic laser lithotripsy and/or cystolitholapaxy. Although complete stent removal can be anticipated, residual fragments are not uncommon. vesical curl. Encrustation in any of these locations may complicate or prevent stent removal in the standard, transurethral manner. Attempting to extract a stent with renal pelvic or ureteral encrustation with excessive force risks fracturing the stent or avulsing the ureter. As such, removal of the encrusted stent presents a challenging endourologic problem. Percutaneous nephrolithotomy (PCNL) is frequently employed to fragment and extract proximal curl encrustations, thus allowing safe extraction of the stent. In addition to
Introduction
U
reteral stents allow reliable renal drainage and are useful adjuncts to endourologic procedures of the upper urinary tract. As a foreign body within the urinary tract, however, they are subject to encrustation depending on urinary supersaturations and increasing dwell time. Encrustation may occur on the proximal curl within the renal pelvis, along the intraureteral portion of the stent, or on the distal intra-
1
Section of Urology, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire. Department of Urologic Sciences, University of British Columbia, Vancouver, Canada. 3 Department of Urology, New York University, New York, New York. 4 Brady Urological Institute, Johns Hopkins University, Baltimore, Maryland. 5 Department of Urology, University of Kentucky, Lexington, Kentucky. 6 Department of Urology, Massachusetts General Hospital, Boston, Massachusetts. 2
1
2
PCNL, alternative and adjunctive solutions have also been proposed. These proposed solutions include shock wave lithotripsy of the encrusted curls, manual scraping of the encrustations from the stent by extraction through a ureteral access sheath, ureteroscopic fragmentation, cystolitholapaxy of the distal encrustations, and open and/or laparoscopic pyelolithotomy and/or cystolithotomy.1–9 Successful outcomes have been noted with many of these techniques, but outcomes are typically reported in single case reports or small case series. None to date have focused specifically on the outcomes of PCNL for removal of the retained and encrusted stent. We thus present a multicenter review to better assess the operative outcomes of PCNL for the primary treatment of encrusted ureteral stents. Materials and Methods
With approval of the respective Institutional Review Boards, the records of patients undergoing PCNL between 2003 and 2010 at six tertiary care hospitals were retrospectively reviewed. Those who underwent PCNL for extraction of proximally encrusted ureteral stents were identified and their records were reviewed. Patient demographic factors, medical comorbidities, and duration of stent dwell time were noted. For those in whom the stent had remained longer than clinically intended, the reason (if known) for prolonged dwell time was recorded. The maximal diameter of proximal stent encrustation as measured by either preoperative kidney, ureter, and bladder (KUB) radiograph or CT scanning was recorded as were the presence of any additional encrustation on the ureteral and/or the intravesical portions of the stent that were identified during surgery. The need for ureteroscopic lithotripsy of ureteral encrustations and/or the need for cystolitholapaxy to free the intravesical portion of the stent were noted. Stones were sent for chemical analysis to varying commercial laboratories based on each institution’s protocol. Analysis techniques were at the discretion of each laboratory. Total operative time, stone composition, the presence and size of residual fragments, postoperative imaging, need for second look PCNL or other secondary procedures, need for blood transfusion, and postoperative complications were also reviewed. Results
We identified the records of 36 patients who had each undergone prone PCNL to remove ureteral stents due to proximal encrustations preventing their routine transurethral removal (Table 1). The calix selected for access was at the discretion of the treating urologists, with each tract dilated to 30F. Two patients had bilateral encrusted retained stents, such that a total of 38 affected renal units were identified and studied. Mean age at time of PCNL was 47.1 years ( – 16.7 years). Fifteen of the 36 patients (42%) were women. The mean duration of stent dwell time before removal was 28.2 months ( – 27.8 months). The longest duration of stent dwell time was 108 months, in which case the patient was unaware of the need for removal. The shortest duration of stent dwell time was 1.1 months in a patient with rapid encrustation during pregnancy. The mean maximal stone burden on the proximal stent curl was 2.9 cm. The explanation for delay in stent removal was identified in 25 cases. In 17 (48%) cases, patients stated that they were either unaware of the stent or had forgotten about it. Three patients
PAIS ET AL.
Table 1. PCNL for Retained Encrusted Stents: Descriptive and Outcomes Data Number of patients Number of renal units Sex Male Female Age (years) Mean indwelling time (months) Reason for prolonged indwelling time Patient ‘‘unaware’’ Patient incarceration Other medical issues Pregnancy Not reported Mean operative time (min) Stent and stones removed by PCNL alone Need for auxiliary procedures Cystolitholapaxy Ureteroscopy Need for second-stage PCNL Stone-free rate
36 38 15 21 47.1 ( – 16.7) 28.2 ( – 27.8) 17 3 3 2 11 162 8
(47.2%) (8.3%) (8.3%) (5.6%) (30.6%) ( – 71) (21%)
22 13 13 24
(58%) (34.2%) (34.2%) (63%)
had major intervening medical problems that prevented timely removal of the ureteral stent (Whipple procedure for pancreatic cancer, gastrointestinal bleeding, lymphoma that led to cardiac arrest). Two cases were associated with pregnancy, with one case of rapid encrustation at 1.1 month and one case of 7.1 months dwell time. Three of these cases involved incarcerated prisoners. Neurogenic comorbidities were noted in five patients, three of whom were quadriplegic, and one each with spina bifida and multiple sclerosis, respectively. Diagnosed metabolic abnormalities included one patient with cystinuria and two patients with hyperparathyroidism. Anatomic abnormalities included three solitary functioning kidneys (two of which were transplanted renal allografts) and one continent catheterizable urinary diversion. Chemical composition of the encrustations was reported in 32 of the 38 cases. Four cases were reported as pure compositions of calcium phosphate, four of struvite, and two of uric acid. The remainder were mixed: two primarily cystine, six primarily struvite, six primarily calcium phosphate, and eight primarily calcium oxalate monohydrate. The mean operative time for the PCNL and any associated procedures performed under the same anesthetic was 162 minutes ( – 70.8 minutes). The mean reported intraoperative estimated blood loss was 110 mL ( – 96.9 mL). None of these patients required intraoperative or perioperative blood transfusions. Intraoperative complications included loss of percutaneous renal access in one patient, which required a repeat procedure, and failure to remove the stent percutaneously in two case, which required shock wave lithotripsy (SWL) in one patient and antegrade ureteroscopy in the other (all Clavien III). Of the 28 patients (74%) who had encrustations on the bladder coil of the stent, 22 (58%) required cystolitholapaxy, 15 were performed at the time of PCNL, and 7 had been performed in a separate procedure before PCNL. Significant encrustation of the ureteral portion of the stent was noted on 25 (66%), of which 13 (34%) required antegrade ureteroscopic laser lithotripsy to sufficiently free the stent for
PERCUTANEOUS NEPHROLITHOTOMY FOR REMOVAL OF ENCRUSTED URETERAL STENTS
removal. Overall, 8 (21%) stents were removed at the time of PCNL without need for auxiliary procedures (i.e., ureteroscopy or cystolitholapaxy). Ultimately all 38 stents were removed. Second look nephroscopy was required in 13 patients to address residual stone and/ or remove the stent and was performed between 2 and 7 days postoperatively. Postoperative imaging included the following types: CT scan in 19, KUB radiograph in 7, renal ultrasound in 5, and nephrostogram in 2. Three patients did not follow-up. Only those without any visualized residual stone were considered stone free. Twenty-four patients (63%) were confirmed to have been rendered stone free on postoperative imaging. Long-term consequences of the encrusted stents included ipsilateral ureteral stricture in one patient who had a struviteencrusted stent indwelling for 96 months, and renal atrophy in another patient who had the stent for 17.5 months (stone composition unknown). Discussion
Instrumental in a multitude of open, laparoscopic, and endourologic ureteral procedures, the placement of a ureteral stent is a common urologic intervention. In the setting of encrustation, however, the routinely office-based procedure of cystoscopic stent removal may not be possible. For the complex proximally encrusted stent, percutaneous nephrolithotomy is recognized as a preferred approach at many centers.8,9 The limited data regarding the specific outcomes of PCNL in this population prompted our present review. As such, we have not assessed all encrusted stents encountered at our respective institutions, only those requiring PCNL for their removal (i.e., those with the largest renal encrustations). In an effort to objectively evaluate encrusted stents, AcostaMiranda and colleagues advocated a novel grading system for ‘‘Forgotten, Encrusted, Calcified’’ (FECal) stents.5 They proposed a classification based upon either linear or bulky calcification. Encrustation is divided into the presence of solely linear encrustation (grade I), bulky encrustation on either pigtail curl (grade II) or both pigtails (grade IV). Linear encrustation of the intraureteral portion of the stent accompanying grade II is upgraded to grade III and encrustation accompanying grade IV is upgraded to grade V. In the 9 patients upon whom this system was based, however, grades I to III were managed successfully with such disparate procedures as simple cystoscopic stent removal, ureteroscopic laser lithotripsy, cystolitholapaxy, SWL, or PCNL. Although it may allow clarification in discussion of some encrusted stents, this grading system does not distinguish between those requiring retrograde or antegrade intervention, between those in whom stents were removed in single versus multistage procedures, or between endoscopic versus open procedures. We did not prospectively categorize using the FECal system, recognizing that the critical finding dictating surgical approach in these patients is proximal pigtail encrustation. This concurs with the findings of Weedin and associates, who presented their experience with management of 55 encrusted stents and confirmed that the burden of encrustation on the proximal curl correlated with the need for multiple procedures as well as with risk of surgical complications.6 In their series, 48% had solely distal encrustation and only 17.3% had complex proximal encrustation requiring PCNL. The outcomes of these patients were not separately reported. Distinct from their report, we focus on the
3
specific group of those undergoing PCNL. Due to the retrospective nature of our series and data capture, we cannot assess the overall denominator of encrusted stents nor assess the factors that may predict which cases will ultimately require PCNL. In our series, PCNL was effective, with 36 (95%) of the 38 stents removed at PCNL. In the remaining two cases, PCNL debulked the proximal stone burden, allowing cystoscopic removal after SWL in one patient and ureteroscopy in the other. No blood transfusions were required, and no major intraoperative complications were noted, with the exception of one case requiring repeat procedure due to the loss of percutaneous access. Postoperative imaging demonstrated that only 63% of patients were stone free. This residual fragment rate of 37% is consistent with reported residual stone rates after PCNL for other complex upper tract stones (17.5% and 43.1% in nonstaghorn and staghorn stones, respectively),10 although we are unaware of previously published stone-free rates after PCNL for encrusted stents. We did use the strict criteria of ‘‘no residual stone fragments’’ to determine success of the procedure from the perspective of stone burden, although as previously noted imaging modalities varied. Perhaps the ease with which small encrusted fragments may be fractured off of the stents and escape complete removal is responsible for the frequency of residual fragments. Our experience most notably highlights that PCNL uncommonly sufficed as a solitary procedure to allow encrusted stent removal. Only 8 (21%) could be removed by PCNL alone. The remainder required antegrade ureteroscopy and/or retrograde cystolitholapaxy to address additional encrustations before the stent could be safely removed. These procedures were performed at the surgeon’s discretion either in the same operative setting before or after PCNL or under a different anesthetic on a different day. Teichman et al reported a uniform approach, beginning with cystolitholapaxy then repositioning and performing PCNL in the same setting if required, in their series of 11 patients.7 One should anticipate the need for ureteroscopic assessment and lithotripsy. Given that 37% had residual fragments in our series, postoperative imaging (ideally CT scans) will be useful to quantitate any residual stone. Nearly one half of the patients in our series were either unaware of their stent or had forgotten about it; thus, we also emphasize the importance of patient counseling that follow-up for stent removal is imperative. Multiple strategies for establishing stent registries have been proposed to ensure timely removal or exchange of placed stents. With a paper-based card system, there was no record of removal of 51 out of the 203 stents retrospectively reviewed.11 With evolving technology, a web-based system with barcode entry and automated emails and a system using short message service (SMS) texting have been employed to remind both patients and physicians of timely stent removal.12,13 Even with an automated, web-based system, however, 13% of placed stents were not captured.12 Clearly, no system to date is infallible, and as such it is important to be prepared to manage the encrusted ureteral stent. Several limitations of this study must be noted. Certainly, as a retrospective study it is subject to the inherent limitations of such design, including selection and recall bias. As the majority of the stents were forgotten by the patients, other historical elements obtained from the patients may also be called into question. While culling the experience of several
4
PAIS ET AL.
investigators at several tertiary care referral centers presented a broader perspective, the details of the initial stent placement at the outside referring institutions were unknown. Heterogeneity of protocols for preoperative evaluation, intraoperative points of technique, staged versus single session operations, and postoperative management at each of the participating institutions limits our ability to prescribe a more detailed, singular approach. Finally, only 19 of the 36 patients had a CT scan for postoperative imaging; thus, both residual stones and subclinical injuries may be underdetected. Conclusion
Ureteral stents represent a single endourologic solution to diverse urologic problems. When encrusted, however, the stent itself poses a new and often greater problem and requires a myriad of endourologic techniques to successfully solve. PCNL is a safe and effective technique for removing a stent with significant proximal encrustation. In our experience, the complex and variable nature of encrustation anywhere along the course of the stent mandates that the surgical team be prepared to perform antegrade ureteroscopy and/or retrograde cystolitholapaxy in order to address the full extent of encrustations that could otherwise prevent safe stent removal. Acknowledgments
The authors wish to acknowledge and thank Rachel Moses, MD, MPH, for assistance in data review and preparation of the manuscript. Additionally, we wish to acknowledge the members of the EDGE research group. Disclosure Statement
No competing financial interests exist. References
1. Bukkapatnam R, Seigne J, Helal M. 1-Step removal of encrusted retained ureteral stents. J Urol 2003;170:1111– 1114. 2. Bostanci Y, Ozden E, Atac F, et al. Single session removal of forgotten encrusted ureteral stents: Combined endourologic approach. Urol Res 2012;40:523–529. 3. Lopez-Huertas HL, Polcari AJ, Hugen CM, et al. A novel technique for the removal of minimally encrusted ureteral stents. J Endourol 2010;24:9–11. 4. Clark C, Bylund J, Paszek M, et al. Novel approach for removal of heavily encrusted ureteral stent. Can J Urol 2009;16:4831–4835.
5. Acosta-Miranda AM, Milner J, Turk TM. The FECal Double-J: A simplified approach in the management of encrusted and retained ureteral stents. J Endourology 2009; 23:409–415. 6. Weedin JW, Coburn M, Link RE. The impact of proximal stone burden on the management of encrusted and retained ureteral stents. J Urol 2011;185:542–547. 7. Teichman JM, Lackner JE, Leveillee RJ, et al. Total endoscopic management of the encrusted ureteral stent under a single anaesthesia. Can J Urol 1997;4:456–459. 8. LeRoy AJ, Williams HJ Jr, Segura JW, et al. Indwelling ureteral stents: Percutaneous management of complications. Radiology 1986;158:219–222. 9. Vanderbrink BA, Rastinehad AR, Ost MC, Smith AD. Encrusted urinary stents: Evaluation and endourologic management. J Endourol 2008;22:902–912. 10. Desai M, DeLisa A, Turna B, et al. The clinical research office of the Endourological Society percutaneous nephrolithotomy global study: Staghorn versus nonstaghorn stones. J Endourol 2011;25:1263–1268. 11. Tang VC, Gillooly J, Lee EW, et al. Ureteric stent card register: A 5-year retrospective analysis. Ann R Coll Surg Engl 2008;90:156–159. 12. Lynch MF, Ghani KR, Frost I, et al. Preventing the forgotten stent: Implementation of a web based stent registry with automatic recall application. Urology 2007;70:423– 426. 13. Sancaktutar AA, Tepeler A, Soylemez H, et al. A solution for medical and legal problems arising from forgotten ureteral stents: Initial results from a reminder short message service (SMS). Urol Res 2012;40:253–258.
Address correspondence to: Vernon M. Pais, Jr., MD Section of Urology Dartmouth Hitchcock Medical Center 1 Medical Center Drive Lebanon, NH 03756 E-mail: [email protected]
Abbreviations Used FECal stents ¼ ‘‘Forgotten, Encrusted, Calcified’’ stents KUB ¼ kidney, ureter, and bladder PCNL ¼ percutaneous nephrolithotomy SMS ¼ short message service SWL ¼ shock wave lithotripsy
JOURNAL OF ENDOUROLOGY Volume XX, Number XX, XXXXXX 2014 ª Mary Ann Liebert, Inc. Pp. ---–--DOI: 10.1089/end.2014.0004
Percutaneous Nephrolithotomy for Removal of Encrusted Ureteral Stents: A Multicenter Study Vernon M. Pais, Jr., MD,1 Ben Chew, MD,2 Ojas Shaw, MD,3 Elias S. Hyams, MD,1 Brian Matlaga, MD,4 Ramakrishna Venkatesh, MBBS,5 Jay Page, MD,5 Ryan F. Paterson, MD,2 Olga Arsovska, BSc,2 Michael Kurtz, MD,6 and Brian H. Eisner, MD6
Abstract
Purpose: Encrusted ureteral stents are a challenging endourologic problem. We performed a multi-institutional review of percutaneous nephrolithotomy (PCNL) as primary treatment for encrusted stents. Materials and Methods: We identified 36 patients who underwent PCNL for treatment of an encrusted stent. A retrospective review was performed to compile details of procedures and outcomes for these patients. Results: In 36 patients, 38 renal units underwent PCNL for encrusted ureteral stents. The mean patient age was 47.1 years ( – 16.7), and the female:male ratio was 15:21. Mean stent indwelling time before removal was 28.2 months ( – 27.8). The reason for long indwelling time was reported in 25 cases; these reasons included ‘‘patient unaware stent needed to be removed’’ (17 cases), pregnancy (2 cases), other comorbidities (3 cases), and patient incarceration (3 cases). In 3 cases, the stent had become encrusted within 3 months of placement. Mean operative time was 162 minutes ( – 71). There were no major intraoperative complications, and no patients required blood transfusion. Litholapaxy was required for bladder coil encrustations in 22 cases (58%), and ureteroscopy with lithotripsy was required for encrustation of the ureteral portion of the stent in 13 cases (34.2%). Second look percutaneous procedures were required in 13 cases (34.2%). The stent was removed at the time of PCNL without need for concomitant or delayed ureteroscopy and/or cystolitholapaxy in 8 cases (21%). Ultimately, all stents were removed successfully. Patients were rendered stone free according to radiographs in 24 cases (63%). Conclusions: In this multicenter review, PCNL is confirmed to be a safe and effective means of addressing the retained and encrusted ureteral stent. PCNL without ureteroscopy or litholapaxy was sufficient in a minority of cases (21%). Adjunctive endourologic modalities are often required, and the surgeon should anticipate the need for concomitant antegrade ureteroscopic laser lithotripsy and/or cystolitholapaxy. Although complete stent removal can be anticipated, residual fragments are not uncommon. vesical curl. Encrustation in any of these locations may complicate or prevent stent removal in the standard, transurethral manner. Attempting to extract a stent with renal pelvic or ureteral encrustation with excessive force risks fracturing the stent or avulsing the ureter. As such, removal of the encrusted stent presents a challenging endourologic problem. Percutaneous nephrolithotomy (PCNL) is frequently employed to fragment and extract proximal curl encrustations, thus allowing safe extraction of the stent. In addition to
Introduction
U
reteral stents allow reliable renal drainage and are useful adjuncts to endourologic procedures of the upper urinary tract. As a foreign body within the urinary tract, however, they are subject to encrustation depending on urinary supersaturations and increasing dwell time. Encrustation may occur on the proximal curl within the renal pelvis, along the intraureteral portion of the stent, or on the distal intra-
1
Section of Urology, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire. Department of Urologic Sciences, University of British Columbia, Vancouver, Canada. 3 Department of Urology, New York University, New York, New York. 4 Brady Urological Institute, Johns Hopkins University, Baltimore, Maryland. 5 Department of Urology, University of Kentucky, Lexington, Kentucky. 6 Department of Urology, Massachusetts General Hospital, Boston, Massachusetts. 2
1
2
PCNL, alternative and adjunctive solutions have also been proposed. These proposed solutions include shock wave lithotripsy of the encrusted curls, manual scraping of the encrustations from the stent by extraction through a ureteral access sheath, ureteroscopic fragmentation, cystolitholapaxy of the distal encrustations, and open and/or laparoscopic pyelolithotomy and/or cystolithotomy.1–9 Successful outcomes have been noted with many of these techniques, but outcomes are typically reported in single case reports or small case series. None to date have focused specifically on the outcomes of PCNL for removal of the retained and encrusted stent. We thus present a multicenter review to better assess the operative outcomes of PCNL for the primary treatment of encrusted ureteral stents. Materials and Methods
With approval of the respective Institutional Review Boards, the records of patients undergoing PCNL between 2003 and 2010 at six tertiary care hospitals were retrospectively reviewed. Those who underwent PCNL for extraction of proximally encrusted ureteral stents were identified and their records were reviewed. Patient demographic factors, medical comorbidities, and duration of stent dwell time were noted. For those in whom the stent had remained longer than clinically intended, the reason (if known) for prolonged dwell time was recorded. The maximal diameter of proximal stent encrustation as measured by either preoperative kidney, ureter, and bladder (KUB) radiograph or CT scanning was recorded as were the presence of any additional encrustation on the ureteral and/or the intravesical portions of the stent that were identified during surgery. The need for ureteroscopic lithotripsy of ureteral encrustations and/or the need for cystolitholapaxy to free the intravesical portion of the stent were noted. Stones were sent for chemical analysis to varying commercial laboratories based on each institution’s protocol. Analysis techniques were at the discretion of each laboratory. Total operative time, stone composition, the presence and size of residual fragments, postoperative imaging, need for second look PCNL or other secondary procedures, need for blood transfusion, and postoperative complications were also reviewed. Results
We identified the records of 36 patients who had each undergone prone PCNL to remove ureteral stents due to proximal encrustations preventing their routine transurethral removal (Table 1). The calix selected for access was at the discretion of the treating urologists, with each tract dilated to 30F. Two patients had bilateral encrusted retained stents, such that a total of 38 affected renal units were identified and studied. Mean age at time of PCNL was 47.1 years ( – 16.7 years). Fifteen of the 36 patients (42%) were women. The mean duration of stent dwell time before removal was 28.2 months ( – 27.8 months). The longest duration of stent dwell time was 108 months, in which case the patient was unaware of the need for removal. The shortest duration of stent dwell time was 1.1 months in a patient with rapid encrustation during pregnancy. The mean maximal stone burden on the proximal stent curl was 2.9 cm. The explanation for delay in stent removal was identified in 25 cases. In 17 (48%) cases, patients stated that they were either unaware of the stent or had forgotten about it. Three patients
PAIS ET AL.
Table 1. PCNL for Retained Encrusted Stents: Descriptive and Outcomes Data Number of patients Number of renal units Sex Male Female Age (years) Mean indwelling time (months) Reason for prolonged indwelling time Patient ‘‘unaware’’ Patient incarceration Other medical issues Pregnancy Not reported Mean operative time (min) Stent and stones removed by PCNL alone Need for auxiliary procedures Cystolitholapaxy Ureteroscopy Need for second-stage PCNL Stone-free rate
36 38 15 21 47.1 ( – 16.7) 28.2 ( – 27.8) 17 3 3 2 11 162 8
(47.2%) (8.3%) (8.3%) (5.6%) (30.6%) ( – 71) (21%)
22 13 13 24
(58%) (34.2%) (34.2%) (63%)
had major intervening medical problems that prevented timely removal of the ureteral stent (Whipple procedure for pancreatic cancer, gastrointestinal bleeding, lymphoma that led to cardiac arrest). Two cases were associated with pregnancy, with one case of rapid encrustation at 1.1 month and one case of 7.1 months dwell time. Three of these cases involved incarcerated prisoners. Neurogenic comorbidities were noted in five patients, three of whom were quadriplegic, and one each with spina bifida and multiple sclerosis, respectively. Diagnosed metabolic abnormalities included one patient with cystinuria and two patients with hyperparathyroidism. Anatomic abnormalities included three solitary functioning kidneys (two of which were transplanted renal allografts) and one continent catheterizable urinary diversion. Chemical composition of the encrustations was reported in 32 of the 38 cases. Four cases were reported as pure compositions of calcium phosphate, four of struvite, and two of uric acid. The remainder were mixed: two primarily cystine, six primarily struvite, six primarily calcium phosphate, and eight primarily calcium oxalate monohydrate. The mean operative time for the PCNL and any associated procedures performed under the same anesthetic was 162 minutes ( – 70.8 minutes). The mean reported intraoperative estimated blood loss was 110 mL ( – 96.9 mL). None of these patients required intraoperative or perioperative blood transfusions. Intraoperative complications included loss of percutaneous renal access in one patient, which required a repeat procedure, and failure to remove the stent percutaneously in two case, which required shock wave lithotripsy (SWL) in one patient and antegrade ureteroscopy in the other (all Clavien III). Of the 28 patients (74%) who had encrustations on the bladder coil of the stent, 22 (58%) required cystolitholapaxy, 15 were performed at the time of PCNL, and 7 had been performed in a separate procedure before PCNL. Significant encrustation of the ureteral portion of the stent was noted on 25 (66%), of which 13 (34%) required antegrade ureteroscopic laser lithotripsy to sufficiently free the stent for
PERCUTANEOUS NEPHROLITHOTOMY FOR REMOVAL OF ENCRUSTED URETERAL STENTS
removal. Overall, 8 (21%) stents were removed at the time of PCNL without need for auxiliary procedures (i.e., ureteroscopy or cystolitholapaxy). Ultimately all 38 stents were removed. Second look nephroscopy was required in 13 patients to address residual stone and/ or remove the stent and was performed between 2 and 7 days postoperatively. Postoperative imaging included the following types: CT scan in 19, KUB radiograph in 7, renal ultrasound in 5, and nephrostogram in 2. Three patients did not follow-up. Only those without any visualized residual stone were considered stone free. Twenty-four patients (63%) were confirmed to have been rendered stone free on postoperative imaging. Long-term consequences of the encrusted stents included ipsilateral ureteral stricture in one patient who had a struviteencrusted stent indwelling for 96 months, and renal atrophy in another patient who had the stent for 17.5 months (stone composition unknown). Discussion
Instrumental in a multitude of open, laparoscopic, and endourologic ureteral procedures, the placement of a ureteral stent is a common urologic intervention. In the setting of encrustation, however, the routinely office-based procedure of cystoscopic stent removal may not be possible. For the complex proximally encrusted stent, percutaneous nephrolithotomy is recognized as a preferred approach at many centers.8,9 The limited data regarding the specific outcomes of PCNL in this population prompted our present review. As such, we have not assessed all encrusted stents encountered at our respective institutions, only those requiring PCNL for their removal (i.e., those with the largest renal encrustations). In an effort to objectively evaluate encrusted stents, AcostaMiranda and colleagues advocated a novel grading system for ‘‘Forgotten, Encrusted, Calcified’’ (FECal) stents.5 They proposed a classification based upon either linear or bulky calcification. Encrustation is divided into the presence of solely linear encrustation (grade I), bulky encrustation on either pigtail curl (grade II) or both pigtails (grade IV). Linear encrustation of the intraureteral portion of the stent accompanying grade II is upgraded to grade III and encrustation accompanying grade IV is upgraded to grade V. In the 9 patients upon whom this system was based, however, grades I to III were managed successfully with such disparate procedures as simple cystoscopic stent removal, ureteroscopic laser lithotripsy, cystolitholapaxy, SWL, or PCNL. Although it may allow clarification in discussion of some encrusted stents, this grading system does not distinguish between those requiring retrograde or antegrade intervention, between those in whom stents were removed in single versus multistage procedures, or between endoscopic versus open procedures. We did not prospectively categorize using the FECal system, recognizing that the critical finding dictating surgical approach in these patients is proximal pigtail encrustation. This concurs with the findings of Weedin and associates, who presented their experience with management of 55 encrusted stents and confirmed that the burden of encrustation on the proximal curl correlated with the need for multiple procedures as well as with risk of surgical complications.6 In their series, 48% had solely distal encrustation and only 17.3% had complex proximal encrustation requiring PCNL. The outcomes of these patients were not separately reported. Distinct from their report, we focus on the
3
specific group of those undergoing PCNL. Due to the retrospective nature of our series and data capture, we cannot assess the overall denominator of encrusted stents nor assess the factors that may predict which cases will ultimately require PCNL. In our series, PCNL was effective, with 36 (95%) of the 38 stents removed at PCNL. In the remaining two cases, PCNL debulked the proximal stone burden, allowing cystoscopic removal after SWL in one patient and ureteroscopy in the other. No blood transfusions were required, and no major intraoperative complications were noted, with the exception of one case requiring repeat procedure due to the loss of percutaneous access. Postoperative imaging demonstrated that only 63% of patients were stone free. This residual fragment rate of 37% is consistent with reported residual stone rates after PCNL for other complex upper tract stones (17.5% and 43.1% in nonstaghorn and staghorn stones, respectively),10 although we are unaware of previously published stone-free rates after PCNL for encrusted stents. We did use the strict criteria of ‘‘no residual stone fragments’’ to determine success of the procedure from the perspective of stone burden, although as previously noted imaging modalities varied. Perhaps the ease with which small encrusted fragments may be fractured off of the stents and escape complete removal is responsible for the frequency of residual fragments. Our experience most notably highlights that PCNL uncommonly sufficed as a solitary procedure to allow encrusted stent removal. Only 8 (21%) could be removed by PCNL alone. The remainder required antegrade ureteroscopy and/or retrograde cystolitholapaxy to address additional encrustations before the stent could be safely removed. These procedures were performed at the surgeon’s discretion either in the same operative setting before or after PCNL or under a different anesthetic on a different day. Teichman et al reported a uniform approach, beginning with cystolitholapaxy then repositioning and performing PCNL in the same setting if required, in their series of 11 patients.7 One should anticipate the need for ureteroscopic assessment and lithotripsy. Given that 37% had residual fragments in our series, postoperative imaging (ideally CT scans) will be useful to quantitate any residual stone. Nearly one half of the patients in our series were either unaware of their stent or had forgotten about it; thus, we also emphasize the importance of patient counseling that follow-up for stent removal is imperative. Multiple strategies for establishing stent registries have been proposed to ensure timely removal or exchange of placed stents. With a paper-based card system, there was no record of removal of 51 out of the 203 stents retrospectively reviewed.11 With evolving technology, a web-based system with barcode entry and automated emails and a system using short message service (SMS) texting have been employed to remind both patients and physicians of timely stent removal.12,13 Even with an automated, web-based system, however, 13% of placed stents were not captured.12 Clearly, no system to date is infallible, and as such it is important to be prepared to manage the encrusted ureteral stent. Several limitations of this study must be noted. Certainly, as a retrospective study it is subject to the inherent limitations of such design, including selection and recall bias. As the majority of the stents were forgotten by the patients, other historical elements obtained from the patients may also be called into question. While culling the experience of several
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investigators at several tertiary care referral centers presented a broader perspective, the details of the initial stent placement at the outside referring institutions were unknown. Heterogeneity of protocols for preoperative evaluation, intraoperative points of technique, staged versus single session operations, and postoperative management at each of the participating institutions limits our ability to prescribe a more detailed, singular approach. Finally, only 19 of the 36 patients had a CT scan for postoperative imaging; thus, both residual stones and subclinical injuries may be underdetected. Conclusion
Ureteral stents represent a single endourologic solution to diverse urologic problems. When encrusted, however, the stent itself poses a new and often greater problem and requires a myriad of endourologic techniques to successfully solve. PCNL is a safe and effective technique for removing a stent with significant proximal encrustation. In our experience, the complex and variable nature of encrustation anywhere along the course of the stent mandates that the surgical team be prepared to perform antegrade ureteroscopy and/or retrograde cystolitholapaxy in order to address the full extent of encrustations that could otherwise prevent safe stent removal. Acknowledgments
The authors wish to acknowledge and thank Rachel Moses, MD, MPH, for assistance in data review and preparation of the manuscript. Additionally, we wish to acknowledge the members of the EDGE research group. Disclosure Statement
No competing financial interests exist. References
1. Bukkapatnam R, Seigne J, Helal M. 1-Step removal of encrusted retained ureteral stents. J Urol 2003;170:1111– 1114. 2. Bostanci Y, Ozden E, Atac F, et al. Single session removal of forgotten encrusted ureteral stents: Combined endourologic approach. Urol Res 2012;40:523–529. 3. Lopez-Huertas HL, Polcari AJ, Hugen CM, et al. A novel technique for the removal of minimally encrusted ureteral stents. J Endourol 2010;24:9–11. 4. Clark C, Bylund J, Paszek M, et al. Novel approach for removal of heavily encrusted ureteral stent. Can J Urol 2009;16:4831–4835.
5. Acosta-Miranda AM, Milner J, Turk TM. The FECal Double-J: A simplified approach in the management of encrusted and retained ureteral stents. J Endourology 2009; 23:409–415. 6. Weedin JW, Coburn M, Link RE. The impact of proximal stone burden on the management of encrusted and retained ureteral stents. J Urol 2011;185:542–547. 7. Teichman JM, Lackner JE, Leveillee RJ, et al. Total endoscopic management of the encrusted ureteral stent under a single anaesthesia. Can J Urol 1997;4:456–459. 8. LeRoy AJ, Williams HJ Jr, Segura JW, et al. Indwelling ureteral stents: Percutaneous management of complications. Radiology 1986;158:219–222. 9. Vanderbrink BA, Rastinehad AR, Ost MC, Smith AD. Encrusted urinary stents: Evaluation and endourologic management. J Endourol 2008;22:902–912. 10. Desai M, DeLisa A, Turna B, et al. The clinical research office of the Endourological Society percutaneous nephrolithotomy global study: Staghorn versus nonstaghorn stones. J Endourol 2011;25:1263–1268. 11. Tang VC, Gillooly J, Lee EW, et al. Ureteric stent card register: A 5-year retrospective analysis. Ann R Coll Surg Engl 2008;90:156–159. 12. Lynch MF, Ghani KR, Frost I, et al. Preventing the forgotten stent: Implementation of a web based stent registry with automatic recall application. Urology 2007;70:423– 426. 13. Sancaktutar AA, Tepeler A, Soylemez H, et al. A solution for medical and legal problems arising from forgotten ureteral stents: Initial results from a reminder short message service (SMS). Urol Res 2012;40:253–258.
Address correspondence to: Vernon M. Pais, Jr., MD Section of Urology Dartmouth Hitchcock Medical Center 1 Medical Center Drive Lebanon, NH 03756 E-mail: [email protected]
Abbreviations Used FECal stents ¼ ‘‘Forgotten, Encrusted, Calcified’’ stents KUB ¼ kidney, ureter, and bladder PCNL ¼ percutaneous nephrolithotomy SMS ¼ short message service SWL ¼ shock wave lithotripsy
