Stesura Seveso Archivio Italiano di Urologia e Andrologia 2024; 96(4):13163 1 ORIGINAL PAPER stents (1). An encrusted stent is defined as one that can- not be removed simply by cystoscopy due to calcification or stone formation around the stent (1, 2). Several risk factors have been described, namely indwelling time and bacterial colonization, as well as patient specific factors and the physical characteristics of the stent (3). El-Faqih et al. proved that the incidence of stent encrustation increases with indwelling time, reporting 9.2% of stents removed before 6 weeks were encrusted compared to 47.5% removed between 6 to 12 weeks (4). Nowadays there is no consensus around the best man- agement of this type of complication. Its approach depends on the severity and location of the encrustation. Some classification for the encrusted stents (ESs) had been published in the last years, namely the KUB score and the forgotten, encrusted and calcified (FECal) grading system. The first one, KUB system is based on the degree of encrus- tation of the stent in the kidney, ureter and bladder, grad- ing it from 1 to 5, and it’s supposed to identify those that will be surgically challenging to remove (5). The later, is based on the stone size, location and degree of stent encrustation, and graded from 1 to 5, proposing also a treatment algorithm (2, 6). In 2021, Manzo et al. proposed a novel system, the V-GUES, which aims to propose a visu- al classification for ESs that help to guide the choice of the appropriate treatment. This system is based on visual inter- pretation of CT scans and divides it into 4 categories: group A includes distal calcification, sparing the ureteral and proximal portions of the stent; group B includes calcifica- tion of the distal and ureteral portions of the stent, sparing the proximal loop; group C includes proximal calcification, with or without calcification of the distal portion, but spar- ing the ureteral portion of the stent; and finally group D includes calcification of the proximal and ureteral portions of the stent, with or without calcification of the distal por- tion. The authors advocate that their classification system is associated with the number of procedures required for a patient to be stent-free, stone-free rate and complications. They suggested that this classification will allow urologist to choose the most reliable intervention (1). Based on the aforementioned studies, the authors intended to prove that the Endoscopic Combined Intra-Renal Surgery (ECIRS) is the best choice when there’s an encrusted prox- imal loop of a ureteral stent. Background: Ureteral stents are one of the most used devices in Urology, allowing drainage of the upper urinary system, and can be used either in elective or emergency procedures. However, as a foreign body inside the urinary system, they are subject to encrustation. Encrustation is one of the burdens seen with double-J stents and, to date, there is no consensus about its best management. This study aims to prove that Endoscopic Combined Intra-Renal Surgery (ECIRS) is the best choice when there’s an encrusted proximal loop of a ureteral stent. Methods: The authors conducted a retrospective cohort study of patients with an encrusted proximal loop of the ureteral stent who underwent surgery at a single center, comparing ECIRS with other procedures. Results: Between July 2011 and June of 2024, 33 patients (18 females and 15 males) were submitted to surgery. The median indwelling time of the stent was 11 (8-19) months and a stent- free rate of 100% was achieved. The authors demonstrated a significant stone-free rate of 61.1% following ECIRS compared to merely 20% with other procedures (p = 0.023). Notably, while the complication rate was low across all procedures, the ECIRS group exhibited fewer complications (5.6%) than those undergoing alternate techniques (13.3%), though this difference was not statistically significant (p = 0.439). Conclusions: Our study advocates for ECIRS as the preferred initial treatment for encrusted proximal ureteral stents, as it facilitates superior stone clearance, minimizes complications, and maintains comparable operative efficiency. This research contributes valuable insights into the management of challeng- ing cases involving encrusted ureteral stents, calling for future studies to further validate these findings. KEY WORDS: Encrusted stent; Lithiasis; Endoscopic combined intra-renal surgery. Submitted 26 September 2024; Accepted 27 September 2024 INTRODUCTION Ureteral stents are one of the most used devices in Urology. They allow the drainage of the upper urinary system and are a powerful tool to use either in elective or emergency procedures. However, as a foreign body inside the urinary system, they are subject to encrustation. Encrustation is one of the burdens seen with double-J Should patients with encrusted JJ stents involving the proximal/renal loop undergo primarily endoscopic combined intrarenal surgery? Alexandra Rocha, Gonçalo Mendes, Sofia Mesquita, Mariana Madanelo, João Vital, Miguel Marques-Monteiro, Nuno Vinagre, Martinha Magalhães, Beatriz Oliveira, Guilherme Gonçalves, Vítor Cavadas, Avelino Fraga Urology Department, Centro Hospitalar e Universitário de Santo António, Unidade Local de Saúde de Santo António, Porto, Portugal. DOI: 10.4081/aiua.2024.13163 Summary Archivio Italiano di Urologia e Andrologia 2024; 96(4):13163 A. Rocha, G. Mendes, Sofia Mesquita, et L. 2 MATERIALS AND METHODS We conducted a retrospective cohort study of all patients who were found to have an encrusted JJ stent and under- went surgical procedures for its removal in our center between July 2011 and June of 2024 (54 patients). From this group of patients, the ones with proximal loop encrus- tation were selected, based on preoperative CT scans and the V-GUES classification. The patients selected belonged to the C and D groups from this classification. All patients without a preoperative CT scan were excluded. All clinical and surgical data were collected from patients' files, focusing on age, sex, height and weight and renal function (serum creatinine levels). We also gathered infor- mation about the procedure during which the stent was ini- tially placed, the time of diagnosis of the encrustation and the duration of the catheterization. We registered the type and number of procedures needed to achieve a stone free status, that was defined as the absence of any fragments in the postoperative imaging studies, and a stent-free status. All patients underwent surgery in our hospital, by a sin- gle surgeon. Treatment decisions were based on the sur- geon’s preference. The surgeries performed were semi- rigid ureteroscopy (srURS), flexible ureteroscopy (fURS), per- cutaneous nephrolithotomy (PCNL) and endoscopic combined intrarenal surgery (ECIRS). All patients with positive cul- tures were treated with antibiotics before the surgery, and all were given perioperative antibiotic prophylaxis. Other data collected included the postoperative complications, including the first 30 days, and classified according to the Clavien-Dindo classification. Data was collected in a SPSS file. We conducted descrip- tive statistics for all the variables, presenting their means or median according to the presence (or not) of a normal distribution. The categorical and nominal variables are presented in frequency tables. To compare means between variables we used a t-sample test. The correla- tion between variables was ascertained using Pearson cor- relation and logistic regression was made to obtain odds ratio of the variables, were applicable. Differences were considered statistically significant if p < 0.05. The study was made in were in accordance with the Helsinki Declaration. RESULTS Between July 2011 and June of 2024, 33 patients with an encrusted proximal/kidney loop of a ureteral stent were submitted to surgery in our centre. There were 18 females and 15 males, with a mean age of 53.9 (± 19.0) years. The mean height and weight were 1.62 (± 0.1) m and 74.1 (± 19.4) kg, respectively. The mean BMI was 27.8 (± 6.0). In 11 cases the encrusted JJ stent was on the left and in 20 cases on the right; we had 2 cases of encrusted stents in a renal transplant. The preoperative serum creatinine levels were 1.1 (± 0.6) mg/dl and the postoperative was 1.1 (± 0.4) mg/dl. We found no statistically significant difference in the creatinine levels pre- and post-operative- ly (p = 0.961) Preoperative urine cultures were also taken, with a posi- tive result in 10 cases and negative in 9. In 12 cases the lab was not able to isolate the bacteria probably due to contamination of the sample. In the other 2 cases the pre- operative urine culture was not available. The isolated strain was Escherichia coli in 6 patients, followed by Proteus mirabilis in 3 cases, and 1 case of Candida albi- cans. These results can be consulted on Table 1. The median indwelling time of the stent was 11 (8-19) months, varying between 5 and 71 months. We found no correlation between indwelling time and the occurrence of complications (p = 0.830) or the stone-free rate (p = 0.423). Regarding surgical approach, the most performed surgery was endoscopic combined intrarenal surgery in 18 cases of 35 (54.5%), as can be seen on table 2. In 8 patients (24.2%) the surgery chosen was PCNL, 6 patients (18.2%) underwent fURS and 1 patient (3%) underwent srURS. The mean time of procedure was 121.1 (± 44.3) min. When comparing ECIRS with other procedures, the authors found a mean time for combined surgery of 123.6 (± 50.9) min and a mean time a 118.1 (± 36.5) min for other surgeries. There was no statically significant difference between the groups (p = 0.727). We also found no difference between the procedure time and the occurrence of complications (p = 0.523) and the stone-free rate (p = 0.487). In all the cases (100%) the encrusted stent was removed in the first procedure. Regarding the stone-free state, 14 patients (42.4%) were stone free after the first procedure, with 19 (57.6%) patients not achieving this state. Comparing the ECIRS procedure with the other surgeries performed, a stone-free rate of 61.1% was achieved with the ECIRS procedure, while other procedures resulted in a 20% stone-free rate. Comparing these rates, we found a correlation between the choice of ECIRS and the stone-free rate (p = 0.023, OR 6.3, 95% CI:1.3-30.5). This data can be seen on Table 3. Table 1. Results of urine cultures. Urine culture Frequency (%) E. coli 6 (60.7%) P. mirabilis 3 (30%) C. albicans 1 (10%) Table 2. Frequency table of the surgeries performed. Surgery Frequency (%) Combined access 18 (54.5%) PCNL 8 (24.2%) Flexible ureteroscopy 6 (18.2%) Semirigid ureteroscopy 1 (3%) Table 3. Comparing ECIRS with other procedures regarding stent-free, stone-free and complication rate. Combined procedure Other procedures P Stent-free after one procedure 18 (100%) 15 (100%) N/A Stone-free after one procedure 11 (61.1%) 3 (20%) 0.0023 Complication rate 1 (5.6%) 2 (13.3%) 0.439 Archivio Italiano di Urologia e Andrologia 2024; 96(4):13163 3 Should patients with encrusted JJ stents involving the proximal/renal loop undergo primarily endoscopic combined intrarenal surgery? The median hospital stay was 3 (2-3) days. Overall, there were 3 cases (9.1%) of postoperative complications in the first 30 days. Two cases of fever with urinary tract infection (UTI) and 1 case of urinary leakage. Regarding the Clavien-Dindo classification, all fall into the II classifica- tion. Comparing ECIRS with other procedures, we found a complication rate of 5.6% with ECIRS and a 13.8% rate with other procedures; we found no statistically signifi- cant correlation between these variables (p = 0.439). The complications and its frequencies can be seen on table 4. Regarding the necessity of a second procedure, 2 patients needed other surgery - 1 patient a fURS (first procedure was a mini-PCNL), 1 mini-PCNL (first procedure was fURS). No complication was reported on these cases. DISCUSSION Encrusted ureteral stents are a complex problem to man- age and it may be difficult and risky to treat it (7, 8). Classification systems appear to facilitate the approach of this type of patients. According to Juliebø-Jones et al. (7), it is recommended to use one of the classification systems available. In this study, the authors chose to use the V- GUES classification system as it appears as the most reli- able and useful. The KUB system is based on X-ray images alone, which may render some limitations. The FECal system, despite its more broaden classification, it is only based on 9 patients. (1, 2). The classification was used to select patients to enter the study, and only the ones categorized as C or D were selected - which means with the presence of encrusted proximal loop of the stent was the selection criteria. Some authors already proposed that the location of the encrustation will determine the surgical modality required for the management of the ureteral stent, and the authors from V-GUES already suggest that combined sur- gery was associated with best stone-free and stent-free rate (1, 2). The main objective of this study is to propose ECIRS, with combined percutaneous surgery and retro- grade endoscopic surgery, as the best first approach to managed encrusted proximal loops of ureteral stents. This study harbours some limitations inherent to its ret- rospective design and relatively small patient cohort. However, due to the nature of this type of cases and its relative scarcity, the authors believe that a prospective study is not feasible. The cases were all performed by the same surgeon, with plenty of experience in lithiasis sur- gery, which could help to explain the good results. The data collected gathered information from patients with an encrusted proximal/kidney loop of a ureteral stent that were submitted to surgery in our centre for a period of roughly 13 years. The sample obtained was 33 patients, with 18 women and 15 men. Given the scarcity of reports on these subject, and its relative infrequent occurrence, this number are in line with other single center reports. The median indwelling time of the stent was 11 (8-19) months It is known that the pro- longed indwelling time of stents increases the prevalence and severity of all complica- tions (8). However, we could not find a cor- relation between the occurrence of complications or stone- free rate and the indwelling time of the ureteral stent. We hypothesize that this could be explained by the low level of complications present in the sample. The mean time of procedure for ECIRS was 123.6 (± 50.9) min, that was not statistically significantly different from the mean time of the other procedures (p = 0.727). This shows that, even when comparing operative time, the use of a more complex surgery, like the combined approach, does not imply longer operative times, advo- cating for its use. There was a 100% rate of stent-free patients after the first procedure, independently of the procedure used. This excellent stent-free rate can be explained by the relative short number of cases and the experience of the surgeon. When focusing on the stone-free state, 42.4% of the patients achieved this state after the first procedure. When comparing the two groups, we found a higher stone-free rate when using ECIRS comparing to other procedures (61.1% vs 20%, respectively). In this case, we found a positive correlation between the use of ECIRS and the stone-free status, with a OR of 6.3 (p = 0.023, 95% CI:1.3-30.5). This shows that ECIRS is a more effec- tive procedure comparing to the other procedures, in cases of encrusted stent, namely with proximal loop encrustation. Some authors already proposed that PCNL should be used in encrusted proximal loops stent. Pais et al. state that only 8% of the stents could be removed by PCNL alone, suggesting that additional procedures may be needed (9). Our results show that in proximal loops, ECIRS should be preferred as first-line as it is the most successful surgery. When looking at the complications rate, the group had a very low complication rate and only with Clavien-Dindo II. Once again, this could probably be explained by the experience of the surgeon and the limited number of cases analysed. Despite not being statistically significant, the complication rate was lower when using the com- bined approach, supporting its primary use. There was need for a second procedure in 2 patients. All the patients needed at least one procedure with a percu- taneous access and others with retrograde endoscopic surgery. This is also in favour with the proposed theory (all needed combined surgery), even if it was in two sep- arate procedures. This supports the theory of using com- bined approach as the first choice in this type of patients. In the remaining patients, the residual stone burden was very little and didn’t need other procedure. Weeding et al. reported that patient with proximal encrust- ed stents required more procedures to remove the stent and the stone burden (10). Our study group reports that Table 4. Description of complications. Procecure Type of Management Clavien-Dindo complication classification Complication nº1 ECIRS UTI antibiotics II Complication nº2 Other UTI antibiotics II Complication nº3 Other Urinary leakage Vesical cathetherization II + antibiotics Archivio Italiano di Urologia e Andrologia 2024; 96(4):13163 A. Rocha, G. Mendes, Sofia Mesquita, et L. 4 the used of combined surgery approach can improve out- comes and reduce the number of surgeries needed to treat this type of patients. CONCLUSIONS Encrusted ureteral stents poses a significant challenge for urologist. There is a lack of standardized treatment in this area. The authors propose combined surgery as the first choice for the treatment of encrusted proximal loops of ureteral stents, as it is associated with better stone-free rate and fewer complications, while not increasing opera- tive time. REFERENCES 1. Manzo BO, Alarcon P, Lozada E, et al. A Novel Visual Grading for Ureteral Encrusted Stent Classification to Help Decide the Endourologic Treatment. J Endourol. 2021; 35:1314-9. 2. Acosta-Miranda AM, Milner J, Turk TMT. The FECal Double-J: A Simplified Approach in the Management of Encrusted and Retained Ureteral Stents. J Endourol. 2009; 23:409-15. 3. Tomer N, Garden E, Small A, Palese M. Ureteral Stent Encrustation: Epidemiology, Pathophysiology, Management and Current Technology. J Urol. 2021; 205:68-77. 4. El-Faqih SR, Shamsuddin AB, Chakrabarti A, et al. Polyurethane Internal Ureteral Stents in Treatment of Stone Patients: Morbidity Related to Indwelling Times. J Urol. 1991; 146:1487-91. 5. Arenas JL, Shen JK, Keheila M, et al. Kidney, Ureter, and Bladder (KUB): A Novel Grading System for Encrusted Ureteral Stents. Urology. 2016; 97:51-5. 6. Guner E, Gokhan Seker K. Comparison of Two Different Scoring Systems in Encrusted Ureteral Stent Management: A Single-Center Experience. Urol J. 2020; 17:248-251. 7. Juliebø-Jones P, Pietropaolo A, Sørstrand Æsøy M, et al. Endourological management of encrusted ureteral stents: An up-to- date guide and treatment algorithm on behalf of the European Association of Urology Young Academic Urology Urolithiasis Group. Cent European J Urol. 2021; 74:571-8. 8. Adanur S, Ozkaya F. Challenges in Treatment and Diagnosis of forgotten/encrusted double-J Ureteral stents: the Largest single-center Experience. Ren Fail. 2016; 38:920-6. 9. Pais VM, Chew B, Shaw O, et al. Percutaneous Nephrolithotomy for Removal of Encrusted Ureteral Stents: A Multicenter Study. J Endourol. 2014; 28:1188-91. 10. Weedin JW, Coburn M, Link RE. The Impact of Proximal Stone Burden on the Management of Encrusted and Retained Ureteral Stents. J Urol. 2011; 185:542-7. Correspondence Maria Alexandra Ferreira Rocha (Corresponding Author) marialexandrarocha@gmail.com Gonçalo Mendes goncalo.grilomendes@gmail.com Sofia Mesquita sofiaoplmesquita@gmail.com Mariana Madanelo marianacmadanelo@gmail.com João Vital joaopvital@gmail.com Miguel Marques-Monteiro mmonteiro.iam@gmail.com Nuno Vinagre nunomrvinagre@gmail.com Martinha Magalhães martinha.a.magalhaes@gmail.com Beatriz Oliveira ana.bia.5@hotmail.com Guilherme Gonçalves guilha.gon@gmail.com Vitor Cavadas vcavadas@gmail.com Avelino Fraga avfraga@gmail.com Urology Department, Centro Hospitalar e Universitário de Santo António, Unidade Local de Saúde de Santo António, Porto, Portugal Conflict of interest: The authors declare no potential conflict of interest.