Urolithiasis DOI 10.1007/s00240-015-0782-4
ORIGINAL PAPER
Extracorporeal shock wave lithotripsy in the primary treatment of encrusted ureteral stents Lokman Irkilata1 · Berat Cem Ozgur2 · Ahmet Ali Sancaktutar3 · Ekrem Akdeniz1 · Mustafa Aydin1 · Huseyin Cihan Demirel1 · Hasan Riza Aydin1 · Omer Gokhan Doluoglu2 · Berkan Resorlu2 · Mustafa Kemal Atilla1
Received: 20 January 2015 / Accepted: 6 May 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Double pigtail (JJ) ureteral stents, are the most commonly used method of urinary diversion in the ureteral obstructions. Encrustations may occur as a result of prolonged exposure due to forgetting these stents in the body. Removing these materials might be an annoyance. Fortyfour patients from three tertiary referral centres with forgotten JJ stents left in them between the years 2007 and 2014 were included in the study. Stents could not be removed by attempted cystoscopy. As an alternative approach, extracorporeal shock wave lithotripsy (ESWL) was the first choice since it is minimally invasive. The results of that treatment are presented along with the relevant demographic data. JJ stenting for urolithiasis was performed in 36 patients, after open surgery in five patients, and for oncological reasons in three patients. ESWL was applied to stents or to any suspicious region adjacent to the stent. In 29 of 44 patients, the stents were easily removed under cystoscopic procedures while in one patient the fragmented residual stent was spontaneously excreted. In eight patients, ureteroscopy was required; in five patients, percutaneous nephrolithotripsy was required; and in one patient, open surgery was required in order to remove stents. ESWL can be considered as a first-line treatment when a forgotten JJ stent is detected despite all precautions after any kind of urological intervention involving insertion of ureteral stents.
* Lokman Irkilata [email protected] 1
Department of Urology, Samsun Training and Research Hospital, Fevzi Çakmak Mahallesi, Altın Yunus Sokak, Liva Park Sitesi, B‑2 Blok, Ilkadım, Samsun, Turkey
2
Department of Urology, Ankara Training and Research Hospital, Ankara, Turkey
3
Department of Urology, Dicle University, Diyarbakir, Turkey
Keywords Urolithiasis · Double pigtail ureteral stents · Encrustation · Extracorporeal shock wave · Lithotripsy
Introduction In treating ureteral obstructions, the double pigtail ureteral stent (internal stent) is the most frequently used method of urinary diversion. The greater frequency of endourological procedures means that the use and indications for internal stents are also increasing, and clinicians are faced with an accompanying increase in the incidence of forgotten internal stents [1]. Factors affecting this occurrence include, in particular, poor compliance of the patient or, in some cases, failure by doctors to provide sufficient follow-up [2]. If the forgotten stents stay in the body for a long time, possible complications may include urinary system infections, migration, or encrustation of the stent and, more seriously, secondary renal dysfunction [2]. As the time that the stent is left in the body increases, the possibility of encrustation increases. Although the exact mechanism of encrustation is unclear, it seems to be dependent on pH, ionic strength, and biomaterial hydrophobic properties [3]. It is well known that if gross encrustation is present, or if stents cannot be removed or broken on the first attempted retrieval by cystoscope, additional treatment will be required. The optimal treatment of encrusted internal stents continues to be a dilemma for urologists. In our patient series, we examined patients with internal stents forgotten due to clinician- or patient-related factors, where stents could not be removed on the first retrieval attempt. We will present the multi-centered treatment results of extracorporeal shock wave lithotripsy (ESWL) for this patient series as a useful contribution to the discussion on treatment of this common urological condition.
13
Urolithiasis
Materials and methods Forty-four patients with forgotten internal ureteral stents from three separate clinics between 2007 and 2014 were retrospectively investigated. The patient group included those with internal stents forgotten for at least 3 months and where the stent could not be removed or broken during attempted retrieval by cystoscopy. The leading symptom was lumbar pain in ten patients, with infection in two patients, and hematuria in one; in the majority of cases (31 patients), the stents were incidentally detected. The leading symptoms did not influence the therapeutic approach. Encrustation was confirmed by kidney-ureter-bladder X-ray, and its size was also evaluated by X-ray and fluoroscopy. ESWL was performed using two different electrohydraulic lithotripters: Elmed Multimed Classic (Elmed Medical Systems, Turkey) in centers 1 and 2, and Siemens Modularis Uro Plus (Siemens Medical Systems, Germany) in center 3. All patients underwent urinalysis, and those with significant pyuria and bacteriuria were further cultured. Microorganisms were tested for antimicrobial susceptibility, and sessions were delayed until a sterile culture was achieved. As it is less invasive, the first treatment approach identified for these patients was ESWL. In patients where encrustation could be clearly seen, ESWL at 1 Hz was applied under sedation to the region of encrustation. In a majority of cases, it was applied at the proximal end of the stent; in some patients, ESWL was applied along the whole stent. The first routine visit was scheduled for 2 weeks following ESWL. During control visits, KUB X-ray and urinalysis were performed, and removal of JJ stents was attempted if there was no residual calcification. All patients were followed up for at least 6 months after intervention. The present study analyses the ESWL treatment data and results and presents them along with participants’ demographic characteristics. The Statistical Package for Social Sciences (SPSS version 16, Chicago, IL, USA) was used for the analysis. The statistical methods used were descriptive statistics, frequency analysis, and the Mann–Whitney U test. Results are expressed as mean ± standard deviation (SD) or median (min–max). P values less than 0.05 were considered to be statistically significant.
Results The following reasons for internal stent application were identified from patient records: ureteroscopy (URS) (21 patients), retrograde intrarenal stone surgery (RIRS) (9 patients), and percutaneous nephrolithotripsy (PNL)
13
Table 1 Demographic findings and treatment data of patients Mean age
45.6 ± 18.2
Gender (n %) • Female • Male Average energy Average number of shock waves Number of ESWL sessions • 1 Session • 2 Session • 3 Session
21 22 1
Side (n) • Right
21
• Left
23
14 (31.8) 30 (68.2) 19 kV 2708 (2500–3000)
ESWL Extracorporeal shock wave lithotripsy
(6 patients). Three other patients had pyelolithotomy, two had ureteropelvic junction obstruction after surgery, and three had the stent inserted after consultations for non-urological oncological reasons. The general characteristics and applied ESWL treatment data for participating patients are shown in Table 1. After ESWL treatment, the stent was observed to be intact and was easily removed with the cystoscope in 29 patients, and in one patient the residual fragments of the catheter were found to have spontaneously discharged. In 14 further cases, where the internal stent could not be removed with the aid of the cystoscope after at least two ESWL sessions, eight patients had URS, five had PNL, and one required open surgery. Of the 30 patients successfully treated using ESWL, 21 required one session and eight required two sessions. After three sessions, one patient from whom the internal catheter had been removed 2 years previously while leaving a fragment unnoticed in the kidney, the stent had completely fragmented and the patient was observed to have passed most fragments (Fig. 1). In 21 patients, where one session of ESWL was enough to remove the stents, all encrustations were proximally located, and ESWL was applied to that location. This success rate is probably explained by the ease of loosening stent rigidity from the proximal end (upper curl). In 22 patients who underwent two sessions of ESWL, first sessions were applied to the upper curls, and second sessions were applied to the lower curls. When the internal stent could not be removed after ESWL, other surgical approaches were used. In eight patients with catheter removed by URS, a longer segment with linear encrustation was found. Where URS was unsuccessful, five patients had the catheter removed by PNL, and the proximal curly end was found to have intense encrustation. In one patient, where access entry was unsuccessful with PNL, open surgery was completed. As a result,
Urolithiasis
Fig. 1 Plain KUB image (left) showing JJ stent piece forgotten or neglected for 6 years; second image (right) shows the same patient after 3 sessions of ESWL
the internal stent was removed after the first, second, or third ESWL session in 21 patients (47.7 %), 29 patients (65.9 %), and 30 (68.1 %), respectively, from the study sample of 44 patients. Differences among the three centers in the number of ESWL sessions required to dissolve the encrustations and for additional procedures were not statistically significant (Table 2).
One important finding in our patient group was that the median duration with stent inserted was 33 months (3–72 months), and the median size of encrustation was 200 mm2 (100–1500 mm2). Both of these parameters were statistically higher in the group that required additional procedures (Table 3). No stenosis, residual fragments, or urinary tract infections were detected during follow-up.
Table 2 Differences between three centers in number of ESWL sessions required to dissolve encrustations and requirement for additional procedures
Discussion
Center 1
Center 2
Center 3
Total
17 11 5 1
15 10 5 –
12 9 3 –
44 1 Session ESWL 2 Sessions ESWL 3 Sessions ESWL
5
5
4
Additional procedures
Use of the internal stent has an important place in urology practice, for diversion during the removal of obstructions or to provide postoperative drainage after endourological interventions. However, along with its positive contributions, the stent may cause complications such as pain, irritative symptoms and fever in the early period, and complications such as infections, migration, encrustation, and disturbed of renal functions may be observed in the
Table 3 Encrustation size with and without additional procedures Without additional proceduresa
With additional proceduresa
P
n
30
14
Encrustation size (mm2)
200 (100–500)
300 (100–1500)
0.003
Stent indwelling (months)
15 (3–72)
33 (7–120)
0.015
a
Data presented as median (min–max)
13
Urolithiasis
Fig. 2 Plain KUB (left) of JJ stent broken in two places during endoscopic retrieval attempt; second image (right) shows newly inserted JJ stent following retrieval of catheter with aid of a ureteroscope after ESWL session
later period [4–6]. Internal stents are generally produced from polyurethane material and are designed to stay in the body for a few weeks to a few months. The general opinion is that internal stents should be removed or replaced within 2–4 months. However, encrustation of forgotten or neglected stents is an observed late period complication. The encrustation forming on a stent may comprise calcium oxalate and/or calcium phosphate and some struvite [4, 5]. In this patient group, as in the majority of our patients, having previous stone disease is found to increase the risk of encrustation [7–11]. In addition to risk factors such as history of kidney stones, metabolic diseases, and urinary system infections, the risk of encrustation increases with the length of time the stent remains within the patient. The encrusted state of the stent makes removal difficult or impossible. The treatment algorithm for these patients remains relatively unexplored. In the presence of encrustation, every endoscopic manipulation of “forgotten stents” should first and always be preceded by appropriate imaging in order to decide on the safest removal strategy. Second, force should be avoided if removal of the catheter cannot be gently managed by means of cystoscopy. In one patient in our patient group, the lower end of the stent was broken and was removed by use of force. In the same patient, the stent was found to have broken within the ureter (Fig. 2). In another of our patients, the upper pigtail segment of the catheter remaining in the kidney was removed (Fig. 1). For the first of these two patients, the stent was easily removed with
13
the aid of a ureteroscope after one session of ESWL. In the second patient, care had to be taken due to the longevity of the stent (6 years) and its location; no additional intervention was considered and, after three sessions of ESWL, the remainder of the stent fragmented, and most of these fragments were discharged from the kidney. As stated above, the length of time for which the stent remains in the body is a very important factor in both the development of complications and the choice of treatment for forgotten stents. With increasing duration, the complete stent may break down, and stenturia (pieces of the stent discharged in urine) may be observed. With regard to the treatment of forgotten stents, Singh et al. recommended classification by calculated stone load and location of encrustation. They reported that for slight encrustation (less than 100 mm2), removal by cystoscopy should work after two sessions of ESWL [5]. The same study determined that for intense encrustation (more than 400 mm2), ESWL alone may not be appropriate, and it was recommended that endourological approaches such as URS or PNL be used to remove the catheter following ESWL. In our patient group, encrustation was generally slight; the size of lithification was found to be 229 ± 221 mm2. Contrary to Singh et al. recommendation of two sessions of ESWL, one session was found to be sufficient for removal of the stent in 21 of 44 patients. Two sessions of ESWL were required for eight of the patients. In the case of one patient, three sessions of ESWL without additional treatment fragmented the catheter and cleaned the area.
Urolithiasis
In line with Singh et al. recommended treatment algorithm, eight of our patients from whom the internal stent could not be removed with traction had the catheter removed with the aid of URS after two sessions of ESWL. In five patients where URS was unsuccessful, the primary treatment approach adopted was PNL. Percutaneous access was unsuccessful in only one patient, and open surgery was necessary. Participating patients requiring additional endourological intervention were generally those with intense encrustation. In these patients, a third session of ESWL may perhaps have been of additional benefit. However, due to physician preference, only one patient had a third ESWL session in the present study. In general, additional treatment will be required where gross encrustation is present. Depending on the location and degree of encrustation, single or multimodal approaches may be necessary. While ESWL has proved successful for small volume renal coil calcifications [5, 12, 13], it is important to note that the failure rate in the current study is probably due to encrustations caused by delay in solving the patient’s problem. Even if unsuccessful alone, ESWL as a noninvasive first-line treatment may increase the potential success of subsequent endourological procedures as well as shortening the overall duration of treatment [5, 13]. The major limitation of our study is its retrospective design, as the composition of the crystalline material was not studied. In some cases, chemolytic options might be considered, but it is well known that encrustation materials are easily dispersed and it is not always easy to collect samples for determining composition. Another limitation of the present study is that renal functions were not detected in detail before the ESWL sessions as it has been reported that ESWL is indicated only for kidneys with good function, allowing clearance of fragments [5]. Additionally, the study did not directly assess the potential mechanism of encrustation (urine pH, ionic strength, biomaterial hydrophobic properties, etc.). Finally, several physicians from different centres participated, and long-term follow-up details were not evaluated. Any or all of these factors may affect treatment strategies and results and will require investigation in future studies.
Conclusion Internal stents have been in use in urology practice for more than three decades. Some complications may occur with these devices; the patient should be informed of medical problems that may result from the presence of a foreign object in the body if a stent is forgotten, and treatment should not be considered complete until the stent is removed. These steps may be effective in reducing the incidence of forgotten stents and any consequent complications that may develop. On a different note, computerized
tracking programs using SMS and e-mail have been reported to provide successful results in this regard [14, 15]. It would also be more effective if each patient were to receive a copy of the implantation certificate that accompanies every JJ set. However, no matter what precautions are taken, forgotten, and encrusted internal stents that cannot be removed remain a possibility. In this situation, care must be taken, and the use of uncontrolled force in traction should be avoided. In this patient group, ESWL proved to be a feasible first-line treatment. Where ESWL is unsuccessful, URS and PNL may offer suitable treatment alternatives; open surgery should be considered only as a last resort. The length of time that the stent remains forgotten, the intensity of encrustation, and kidney function for spontaneous clearance of fragments is the main factors affecting the success of ESWL. Conflict of interest No conflict of interest was declared by the authors.
References 1. Auge BK, Preminger GM (2002) Ureteral stents and their use in endourology. Curr Opin Urol 12:217–222 2. Sansalone CV, Maione G, Aseni P, Mangoni I, Soldano S, Minetti E, Radaelli L, Civati G (2005) Advantages of short-time ureteric stenting for prevention of urological complications in kidney transplantation: an 18-year experience. Transplant Proc 37:2511–2515 3. Murthy KVR, Reddy SJ, Prasad DV (2010) Endourological management of forgotten encrusted ureteral stents. Int Braz J Urol 36:420–429 4. Witjes JA (1993) Breakage of a silicone double pigtail ureteral stent as a long-term complication. J Urol 150:1898–1899 5. Singh I, Gupta N, Hemal AK, Aron M, Seth A, Dogra PN (2001) Severely encrusted polyurethane ureteral stents: management and analysis of potential risk factors. Urology 58:526–531 6. Polat F, Yesil S, Kirac M, Tan MO, Biri H, Bozkirli I (2005) An uncommon application of shock wave lithotripsy: encrusted double pigtail ureteral stent. Int Urol Nephrol 37:231–233 7. Schulze KA, Wettlaufer JN, Oldani G (1985) Encrustation and stone formation: complication of indwelling ureteral stents. Urology 25:616–618 8. El Faqih SR, Shamsuddin AB, Chakrabarti A, Atassi R, Kardar AH, Osman MK, Husain I (1995) Poly- urethane internal urethral stents in treatment of stone patients: morbidity related to indwelling times. J Urol 153:1817–1820 9. Prodromos GB, Christopher JK (2000) Current management of severely encrusted ureteral stents with a large associated stone burden. J Urol 164:648–650 10. Robert M, Boularan AM, El Sandid M, Grasset D (1997) Double-J ureteric stent encrustations: clinical study on crystal formation on polyurethane stents. Urol Int 58:100–103 11. Finney RP (1982) Double-J and diversion stents. Urol Clin North Am 9:89–91 12. Bostanci Y, Ozden E, Atac F, Yakupoglu YK, Yilmaz AF, Sarikaya S (2012) Single session removal of forgotten encrusted ureteral stents: combined endourological approach. Urol Res 40:611–612
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Urolithiasis 13. Bultitude MF, Tiptaft RC, Glass JM, Dasgupta P (2003) Management of encrusted ureteral stents impacted in upper tract. Urology 62:622–626 14. Ather MH, Talati J, Biyabani R (2000) Physician responsibility for removal of implants: the case for a computerized program for tracking overdue double-J stents. Tech Urol 6:189–192
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15. Sancaktutar AA, Tepeler A, Söylemez H, Penbegül N, Atar M, Bozkurt Y, Yıldırım K (2012) A solution for medical and legal problems arising from forgotten ureteral stents: initial results from a reminder short message service (SMS). Urol Res 40:253–258
ORIGINAL PAPER
Extracorporeal shock wave lithotripsy in the primary treatment of encrusted ureteral stents Lokman Irkilata1 · Berat Cem Ozgur2 · Ahmet Ali Sancaktutar3 · Ekrem Akdeniz1 · Mustafa Aydin1 · Huseyin Cihan Demirel1 · Hasan Riza Aydin1 · Omer Gokhan Doluoglu2 · Berkan Resorlu2 · Mustafa Kemal Atilla1
Received: 20 January 2015 / Accepted: 6 May 2015 © Springer-Verlag Berlin Heidelberg 2015
Abstract Double pigtail (JJ) ureteral stents, are the most commonly used method of urinary diversion in the ureteral obstructions. Encrustations may occur as a result of prolonged exposure due to forgetting these stents in the body. Removing these materials might be an annoyance. Fortyfour patients from three tertiary referral centres with forgotten JJ stents left in them between the years 2007 and 2014 were included in the study. Stents could not be removed by attempted cystoscopy. As an alternative approach, extracorporeal shock wave lithotripsy (ESWL) was the first choice since it is minimally invasive. The results of that treatment are presented along with the relevant demographic data. JJ stenting for urolithiasis was performed in 36 patients, after open surgery in five patients, and for oncological reasons in three patients. ESWL was applied to stents or to any suspicious region adjacent to the stent. In 29 of 44 patients, the stents were easily removed under cystoscopic procedures while in one patient the fragmented residual stent was spontaneously excreted. In eight patients, ureteroscopy was required; in five patients, percutaneous nephrolithotripsy was required; and in one patient, open surgery was required in order to remove stents. ESWL can be considered as a first-line treatment when a forgotten JJ stent is detected despite all precautions after any kind of urological intervention involving insertion of ureteral stents.
* Lokman Irkilata [email protected] 1
Department of Urology, Samsun Training and Research Hospital, Fevzi Çakmak Mahallesi, Altın Yunus Sokak, Liva Park Sitesi, B‑2 Blok, Ilkadım, Samsun, Turkey
2
Department of Urology, Ankara Training and Research Hospital, Ankara, Turkey
3
Department of Urology, Dicle University, Diyarbakir, Turkey
Keywords Urolithiasis · Double pigtail ureteral stents · Encrustation · Extracorporeal shock wave · Lithotripsy
Introduction In treating ureteral obstructions, the double pigtail ureteral stent (internal stent) is the most frequently used method of urinary diversion. The greater frequency of endourological procedures means that the use and indications for internal stents are also increasing, and clinicians are faced with an accompanying increase in the incidence of forgotten internal stents [1]. Factors affecting this occurrence include, in particular, poor compliance of the patient or, in some cases, failure by doctors to provide sufficient follow-up [2]. If the forgotten stents stay in the body for a long time, possible complications may include urinary system infections, migration, or encrustation of the stent and, more seriously, secondary renal dysfunction [2]. As the time that the stent is left in the body increases, the possibility of encrustation increases. Although the exact mechanism of encrustation is unclear, it seems to be dependent on pH, ionic strength, and biomaterial hydrophobic properties [3]. It is well known that if gross encrustation is present, or if stents cannot be removed or broken on the first attempted retrieval by cystoscope, additional treatment will be required. The optimal treatment of encrusted internal stents continues to be a dilemma for urologists. In our patient series, we examined patients with internal stents forgotten due to clinician- or patient-related factors, where stents could not be removed on the first retrieval attempt. We will present the multi-centered treatment results of extracorporeal shock wave lithotripsy (ESWL) for this patient series as a useful contribution to the discussion on treatment of this common urological condition.
13
Urolithiasis
Materials and methods Forty-four patients with forgotten internal ureteral stents from three separate clinics between 2007 and 2014 were retrospectively investigated. The patient group included those with internal stents forgotten for at least 3 months and where the stent could not be removed or broken during attempted retrieval by cystoscopy. The leading symptom was lumbar pain in ten patients, with infection in two patients, and hematuria in one; in the majority of cases (31 patients), the stents were incidentally detected. The leading symptoms did not influence the therapeutic approach. Encrustation was confirmed by kidney-ureter-bladder X-ray, and its size was also evaluated by X-ray and fluoroscopy. ESWL was performed using two different electrohydraulic lithotripters: Elmed Multimed Classic (Elmed Medical Systems, Turkey) in centers 1 and 2, and Siemens Modularis Uro Plus (Siemens Medical Systems, Germany) in center 3. All patients underwent urinalysis, and those with significant pyuria and bacteriuria were further cultured. Microorganisms were tested for antimicrobial susceptibility, and sessions were delayed until a sterile culture was achieved. As it is less invasive, the first treatment approach identified for these patients was ESWL. In patients where encrustation could be clearly seen, ESWL at 1 Hz was applied under sedation to the region of encrustation. In a majority of cases, it was applied at the proximal end of the stent; in some patients, ESWL was applied along the whole stent. The first routine visit was scheduled for 2 weeks following ESWL. During control visits, KUB X-ray and urinalysis were performed, and removal of JJ stents was attempted if there was no residual calcification. All patients were followed up for at least 6 months after intervention. The present study analyses the ESWL treatment data and results and presents them along with participants’ demographic characteristics. The Statistical Package for Social Sciences (SPSS version 16, Chicago, IL, USA) was used for the analysis. The statistical methods used were descriptive statistics, frequency analysis, and the Mann–Whitney U test. Results are expressed as mean ± standard deviation (SD) or median (min–max). P values less than 0.05 were considered to be statistically significant.
Results The following reasons for internal stent application were identified from patient records: ureteroscopy (URS) (21 patients), retrograde intrarenal stone surgery (RIRS) (9 patients), and percutaneous nephrolithotripsy (PNL)
13
Table 1 Demographic findings and treatment data of patients Mean age
45.6 ± 18.2
Gender (n %) • Female • Male Average energy Average number of shock waves Number of ESWL sessions • 1 Session • 2 Session • 3 Session
21 22 1
Side (n) • Right
21
• Left
23
14 (31.8) 30 (68.2) 19 kV 2708 (2500–3000)
ESWL Extracorporeal shock wave lithotripsy
(6 patients). Three other patients had pyelolithotomy, two had ureteropelvic junction obstruction after surgery, and three had the stent inserted after consultations for non-urological oncological reasons. The general characteristics and applied ESWL treatment data for participating patients are shown in Table 1. After ESWL treatment, the stent was observed to be intact and was easily removed with the cystoscope in 29 patients, and in one patient the residual fragments of the catheter were found to have spontaneously discharged. In 14 further cases, where the internal stent could not be removed with the aid of the cystoscope after at least two ESWL sessions, eight patients had URS, five had PNL, and one required open surgery. Of the 30 patients successfully treated using ESWL, 21 required one session and eight required two sessions. After three sessions, one patient from whom the internal catheter had been removed 2 years previously while leaving a fragment unnoticed in the kidney, the stent had completely fragmented and the patient was observed to have passed most fragments (Fig. 1). In 21 patients, where one session of ESWL was enough to remove the stents, all encrustations were proximally located, and ESWL was applied to that location. This success rate is probably explained by the ease of loosening stent rigidity from the proximal end (upper curl). In 22 patients who underwent two sessions of ESWL, first sessions were applied to the upper curls, and second sessions were applied to the lower curls. When the internal stent could not be removed after ESWL, other surgical approaches were used. In eight patients with catheter removed by URS, a longer segment with linear encrustation was found. Where URS was unsuccessful, five patients had the catheter removed by PNL, and the proximal curly end was found to have intense encrustation. In one patient, where access entry was unsuccessful with PNL, open surgery was completed. As a result,
Urolithiasis
Fig. 1 Plain KUB image (left) showing JJ stent piece forgotten or neglected for 6 years; second image (right) shows the same patient after 3 sessions of ESWL
the internal stent was removed after the first, second, or third ESWL session in 21 patients (47.7 %), 29 patients (65.9 %), and 30 (68.1 %), respectively, from the study sample of 44 patients. Differences among the three centers in the number of ESWL sessions required to dissolve the encrustations and for additional procedures were not statistically significant (Table 2).
One important finding in our patient group was that the median duration with stent inserted was 33 months (3–72 months), and the median size of encrustation was 200 mm2 (100–1500 mm2). Both of these parameters were statistically higher in the group that required additional procedures (Table 3). No stenosis, residual fragments, or urinary tract infections were detected during follow-up.
Table 2 Differences between three centers in number of ESWL sessions required to dissolve encrustations and requirement for additional procedures
Discussion
Center 1
Center 2
Center 3
Total
17 11 5 1
15 10 5 –
12 9 3 –
44 1 Session ESWL 2 Sessions ESWL 3 Sessions ESWL
5
5
4
Additional procedures
Use of the internal stent has an important place in urology practice, for diversion during the removal of obstructions or to provide postoperative drainage after endourological interventions. However, along with its positive contributions, the stent may cause complications such as pain, irritative symptoms and fever in the early period, and complications such as infections, migration, encrustation, and disturbed of renal functions may be observed in the
Table 3 Encrustation size with and without additional procedures Without additional proceduresa
With additional proceduresa
P
n
30
14
Encrustation size (mm2)
200 (100–500)
300 (100–1500)
0.003
Stent indwelling (months)
15 (3–72)
33 (7–120)
0.015
a
Data presented as median (min–max)
13
Urolithiasis
Fig. 2 Plain KUB (left) of JJ stent broken in two places during endoscopic retrieval attempt; second image (right) shows newly inserted JJ stent following retrieval of catheter with aid of a ureteroscope after ESWL session
later period [4–6]. Internal stents are generally produced from polyurethane material and are designed to stay in the body for a few weeks to a few months. The general opinion is that internal stents should be removed or replaced within 2–4 months. However, encrustation of forgotten or neglected stents is an observed late period complication. The encrustation forming on a stent may comprise calcium oxalate and/or calcium phosphate and some struvite [4, 5]. In this patient group, as in the majority of our patients, having previous stone disease is found to increase the risk of encrustation [7–11]. In addition to risk factors such as history of kidney stones, metabolic diseases, and urinary system infections, the risk of encrustation increases with the length of time the stent remains within the patient. The encrusted state of the stent makes removal difficult or impossible. The treatment algorithm for these patients remains relatively unexplored. In the presence of encrustation, every endoscopic manipulation of “forgotten stents” should first and always be preceded by appropriate imaging in order to decide on the safest removal strategy. Second, force should be avoided if removal of the catheter cannot be gently managed by means of cystoscopy. In one patient in our patient group, the lower end of the stent was broken and was removed by use of force. In the same patient, the stent was found to have broken within the ureter (Fig. 2). In another of our patients, the upper pigtail segment of the catheter remaining in the kidney was removed (Fig. 1). For the first of these two patients, the stent was easily removed with
13
the aid of a ureteroscope after one session of ESWL. In the second patient, care had to be taken due to the longevity of the stent (6 years) and its location; no additional intervention was considered and, after three sessions of ESWL, the remainder of the stent fragmented, and most of these fragments were discharged from the kidney. As stated above, the length of time for which the stent remains in the body is a very important factor in both the development of complications and the choice of treatment for forgotten stents. With increasing duration, the complete stent may break down, and stenturia (pieces of the stent discharged in urine) may be observed. With regard to the treatment of forgotten stents, Singh et al. recommended classification by calculated stone load and location of encrustation. They reported that for slight encrustation (less than 100 mm2), removal by cystoscopy should work after two sessions of ESWL [5]. The same study determined that for intense encrustation (more than 400 mm2), ESWL alone may not be appropriate, and it was recommended that endourological approaches such as URS or PNL be used to remove the catheter following ESWL. In our patient group, encrustation was generally slight; the size of lithification was found to be 229 ± 221 mm2. Contrary to Singh et al. recommendation of two sessions of ESWL, one session was found to be sufficient for removal of the stent in 21 of 44 patients. Two sessions of ESWL were required for eight of the patients. In the case of one patient, three sessions of ESWL without additional treatment fragmented the catheter and cleaned the area.
Urolithiasis
In line with Singh et al. recommended treatment algorithm, eight of our patients from whom the internal stent could not be removed with traction had the catheter removed with the aid of URS after two sessions of ESWL. In five patients where URS was unsuccessful, the primary treatment approach adopted was PNL. Percutaneous access was unsuccessful in only one patient, and open surgery was necessary. Participating patients requiring additional endourological intervention were generally those with intense encrustation. In these patients, a third session of ESWL may perhaps have been of additional benefit. However, due to physician preference, only one patient had a third ESWL session in the present study. In general, additional treatment will be required where gross encrustation is present. Depending on the location and degree of encrustation, single or multimodal approaches may be necessary. While ESWL has proved successful for small volume renal coil calcifications [5, 12, 13], it is important to note that the failure rate in the current study is probably due to encrustations caused by delay in solving the patient’s problem. Even if unsuccessful alone, ESWL as a noninvasive first-line treatment may increase the potential success of subsequent endourological procedures as well as shortening the overall duration of treatment [5, 13]. The major limitation of our study is its retrospective design, as the composition of the crystalline material was not studied. In some cases, chemolytic options might be considered, but it is well known that encrustation materials are easily dispersed and it is not always easy to collect samples for determining composition. Another limitation of the present study is that renal functions were not detected in detail before the ESWL sessions as it has been reported that ESWL is indicated only for kidneys with good function, allowing clearance of fragments [5]. Additionally, the study did not directly assess the potential mechanism of encrustation (urine pH, ionic strength, biomaterial hydrophobic properties, etc.). Finally, several physicians from different centres participated, and long-term follow-up details were not evaluated. Any or all of these factors may affect treatment strategies and results and will require investigation in future studies.
Conclusion Internal stents have been in use in urology practice for more than three decades. Some complications may occur with these devices; the patient should be informed of medical problems that may result from the presence of a foreign object in the body if a stent is forgotten, and treatment should not be considered complete until the stent is removed. These steps may be effective in reducing the incidence of forgotten stents and any consequent complications that may develop. On a different note, computerized
tracking programs using SMS and e-mail have been reported to provide successful results in this regard [14, 15]. It would also be more effective if each patient were to receive a copy of the implantation certificate that accompanies every JJ set. However, no matter what precautions are taken, forgotten, and encrusted internal stents that cannot be removed remain a possibility. In this situation, care must be taken, and the use of uncontrolled force in traction should be avoided. In this patient group, ESWL proved to be a feasible first-line treatment. Where ESWL is unsuccessful, URS and PNL may offer suitable treatment alternatives; open surgery should be considered only as a last resort. The length of time that the stent remains forgotten, the intensity of encrustation, and kidney function for spontaneous clearance of fragments is the main factors affecting the success of ESWL. Conflict of interest No conflict of interest was declared by the authors.
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