Stesura Seveso Archivio Italiano di Urologia e Andrologia 2023; 95(3):11524 1 ORIGINAL PAPER routine practice of the endourologists, especially after the introduction of the hydrophilic coated UASs with the hub-locking mechanisms and in a study that compared the commonly used UASs they concluded that there were no differences between them as regard safety and effica- cy. Also, less resistance during the insertion of UAS was noted in the pre-stented and dilated ureters (5, 6). UAS can allow repeated access to the renal pelvis without trau- ma to the ureter, improve visibility, protect the uretero- scope, improve drainage and allow rapid extraction of stone fragments (7, 8). Also, UAS will lower intra-renal pressures, which may reduce pyelovenous backflow, leading to a decrease in the risk of infectious complica- tions (9). The routine use of UAS for standard URS remains somewhat controversial (10). UASs can directly damage the ureteral wall and compromise ureteral blood flow transiently (11, 12). The major aim of this study was to assess the efficacy, safety, and feasibility of employing UAS during flexible ureteroscopy for the removal of renal stones 2 cm in size or larger. MATERIAL AND METHODS This retrospective study compared the effectiveness of flex- ible ureteroscopy with and without UAS in the treatment of renal stones 2 cm or larger at “Al-Azhar” and “Benha University Hospitals”. 495 consecutives flexible uretero- scopies were accomplished from January 2021 to February 2023 for kidney and ureter calculi. From them, 112 patients had renal stones 2 cm or more (60 patients with the use of UAS and 52 patients without). Inclusion criteria included patients with renal stones ≥ 2 cm, while exclusion criteria were patients with ureteric stones or combined renal and ureteric stones, patients with kidney calculi < 2 cm, patients with related congenital renal abnormalities and cases with incomplete records of postoperative data (Figure 1). The “Faculty of Medicine for Girls at Al-Azhar University in Cairo (FMG-IRB)” in Nasr City, Cairo, Egypt, had accepted the study's protocol with “approval number: 1657”. All procedures were performed under the Helsinki Declaration. As this was a retrospective study, the necessi- ty for obtaining informed permission was waived. We retrieved the following data for all patients of the study: Introduction: The rate of success of retro- grade intrarenal surgery (RIRS) for treating urinary tract stones is high, and the procedure is growing in popularity. The routine use of ureteral access sheath (UAS) remains somewhat controversial. The aim of this study was to assess the efficacy and safety of employing UAS during flexible ureteroscopy for treating renal stones ≥ 2 cm. Methods: This retrospective study was accomplished from January 2021 to February 2023. From 495 consecutives flexible ureteroscopies, 112 patients had renal stones ≥ 2 cm (60 patients with the use of UAS and 52 patients without). The stone-free status was verified after 8 weeks of operation. Results: The average diameter of the renal stones in non-UAS or UAS treated groups was 22.5 mm and 22.6, respectively. None of the groups differed significantly in terms of stone side, stone size, stone position, or Hounsfield unite but there was significant difference (p < 0.001) among two groups as regard pre-opera- tive stenting (cases with UAS had 23.3% pre-operative stenting). Conclusions: It is not always necessary to use UAS in conjunc- tion with flexible ureteroscopy and laser lithotripsy to treat renal calculi bigger than or equal two cm. Without the assis- tance of UAS, the surgery may be carried out successfully and safely. Key WORDS: Retrograde intrarenal surgery; Laser lithotripsy; Ureteral access sheath; Kidney calculi. Submitted 15 june 2023; Accepted 14 July 2023 INTRODUCTION The rate of success of retrograde intrarenal surgery (RIRS) for treating urinary tract calculi is high, and the proce- dure is growing in popularity (1, 2). The first reported introduction of a guide tube (with a polytetrafluoroethyl- ene coating, a length of 38 cm and a diameter of 3 mm) through the ureteral orifice to pass a completely passive flexible ureteroscope was by Takayasu and Aso in 1974 (3). Its initial use was accompanied by a high rate of com- plications; 12 of 43 cases had ureter perforation (eight of them due to ureteral sheath and four cases to other caus- es) (4). In spite of those bad results, the use of ureteral access sheath (UAS) did not stop, and technological devel- opment made it more easy and safe to use UAS during the The outcomes of flexible ureteroscopy for renal calculi of 2 cm or more with and without the use of ureteral access sheath: A retrospective study Basem A. Fathi 1, Ahmed A. Elgammal 1, Tamer A. Abouelgreed 1, Osama M. Ghoneimy 1, Ahmed Y. Aboelsaad 2, Mohamed A. Alhefnawy 3 1 Department of Urology, Faculty of Medicine, Al-Azhar University, Cairo, Egypt; 2 Department of Urology, Faculty of Medicine, Al-Azhar University, Damietta, Egypt; 3 Department of Urology, Faculty of Medicine, Benha University, Egypt. DOI: 10.4081/aiua.2023.11524 Summary Archivio Italiano di Urologia e Andrologia 2023; 95(3):11524 B.A. Fathi, A.A. Elgammal, T.A. Abouelgreed, O.M. Ghoneimy, A.Y. Aboelsaad, M.A. Alhefnawy 2 age, sex, main presentation, previous sur- geries, associated comorbidities, renal function, location and density of the stones, intra and after surgery details, sur- gery duration, stenting duration, stone-free rates (SFR) and any auxiliary procedures. A semi-rigid ureteroscope was used to check the ureter up to the level of the pelvis for any abnormalities and to widen the ureter while the patient was under general anaes- thesia and in the lithotomy position. Another safety guide wire was utilized throughout. The decision for using UAS or not was strictly based on surgeon's prefer- ence and not on patient and stone charac- teristics. The UAS is inserted into the patient at the beginning of the surgery under fluoroscopic guidance, with the sheath's tip resting at the ureteropelvic junction. The Flexor® UAS (Cook Medical) was used; it is a hydrophilic, soft, two- piece device consisting of an inner tapered obturator that is detachable and an out- side functioning sheath that may be any of three lengths (20, 28, or 35). It is offered in a choice of two sizes “10/12F and 12/14F”. The dimension of the sheath is determined by the anatomy of the case and the endo- scope being utilized. The flexible uretero- scope was positioned over a wire under flu- oroscopic guidance on direct vision in cir- cumstances where the UAS was not employed. All stones were fragmented to a very small sizes by means of holmium laser (30 W Litho Quantasystem, Lumenis Pulse™ 120H Boston Scientific) using a 365 -µm holmium laser fiber with power settings of 0.8-1.5 J at 10-15 Hz, except in lower calyceal stones where a 200-µm fiber was used. Two kinds of flexible uretero- scopes were used for all surgeries: “OTU-100SR WiScope® Single-Use Digital Flexible Ureteroscope and LithoVue™ Single-Use Digital Flexible Ureteroscope Boston Scientific”. After laser lithotripsy, stones were repositioned in the col- lecting system, and pieces were removed using a nitinol basket if needed. Patients underwent either plain abdominal X-rays with ultrasonogra- phy or a non-contrast-enhanced spiral computed tomography (CT) scan for radiolucent stones to verify stone-free status after 8 weeks from opera- tion. Success was considered when there was no residual stone or if the residual stone was less than 5 mm. Table 1. Comparison of baseline parameters between studied groups. Without UAS With UAS P N = 52 N = 60 Demographics Age (years) Mean ± SD 42.1 11.6 40.7 10.5 0.505 Range 23 73 20 67 Sex Males N, % 30 57.7% 38 63.3% 0.542 Females N, % 22 42.3% 22 36.7% History Medical Absent N, % 46 88.5% 52 86.7% 0.987 HTN N, % 3 5.8% 4 6.7% NIDDM N, % 2 3.8% 3 5.0% HTN&DM N, % 1 1.9% 1 1.7% Surgical Absent N, % 32 61.5% 37 61.7% 1 PNL N, % 2 3.8% 2 3.3% SWL N, % 9 17.3% 11 18.3% URS N, % 6 11.5% 7 11.7% Pyelolithotomy N, % 2 3.8% 2 3.3% URS and SWL N, % 1 1.9% 1 1.7% Main presentation Loin pain Present N, % 52 100.0% 60 100.0% - Hematuria Absent N, % 42 80.8% 48 80.0% 0.919 Present N, % 10 19.2% 12 20.0% Laboratory data Pus cell Mean ± SD 9.3 17.9 10.3 17.6 0.755 Range 0 100 0 100 Urine culture Absent N, % 40 76.9% 48 80.0% 0.285 E-coli N, % 9 17.3% 8 13.3% Klebsiella N, % 3 5.8% 1 1.7% Staphyloccocus areus N, % 0 0.0% 3 5.0% Blood urea (mg/dL) Mean ± SD 32.0 7.6 32.1 7.4 0.964 Range 18 46 18 46 Serum creatinine (mg/dL) Mean ± SD 1.0 0.2 1.0 0.3 0.324 Range 0.10 1.50 0.50 1.90 Figure 1. A schematic representation of the study. Archivio Italiano di Urologia e Andrologia 2023; 95(3):11524 3 The outcomes of flexible ureteroscopy for renal calculi of 2 cm or more with and without the use of ureteral access sheath Statistical analyses Revisions, coding, tabulation, and intro- duction of the acquired data to a comput- er were made utilizing Statistical Package for Social Science (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp). In order to assess the statistical significance differ- ence between two study groups means, Student T test was used. When compar- ing two non-parametric groups, the Mann-Whitney test was utilized for analy- sis. 𝝌2 test was utilized to analyse the cor- relation among two categorial quantities. A probability (P) is regarded as statistical- ly significant if less than 0.05 at CI (con- fidence interval) 95%. RESULTS The existing research was performed on 52 patients without UAS (first group) and 60 cases with UAS (second group). The indications of ureteroscopy were the fail- ure of other therapies, comorbidities, skeleto-muscular deformity, body habitus and patient preference. No significant dif- ferences were found among both groups concerning demographic data, history (medical and surgical), presentation and laboratory data (Table 1). Additionally, there were no notable variations among the groups concerning the calculi side, dimension, position and Hounsfield unit, as shown in Table 2. The average dimen- sion of the renal calculi in non-UAS or UAS treated groups was 22.5 mm and 22.6, respectively. The mean hardness was 953.6 HU in the first group and 953.1 HU in the second group. Another finding is that there was significant difference (p < 0.001) among both groups as regard pre- operative stenting (cases with UAS had 23.3% pre-operative stenting) (Figure 2). Additionally, as demonstrated in Table 3 and Figure 3, there were no discernible differences among the study groups in terms of intra- or post-intervention com- plications. Two cases were intra-opera- tively converted to standard percutaneous nephrolithotomy (PCNL) in each group based on the surgeon's decision. We also found that cases without UAS required another intervention in 17.3% (5 cases required a 2nd session of URS, and 4 cases required a session of SWL), while those with UAS required another intervention in 10% (4 cases required 2nd session of URS and 2 cases required a session of SWL), with no observable variations among the two groups. In addition, no obvious alter- ations were found between groups con- Figure 2. Pre and post- operative stenting among studied groups. Table 2. Comparison of Stone characteristics between studied groups. Stone characteristics Without UAS With UAS P N = 52 N = 60 Side Left N, % 25 48.1% 29 48.3% 0.978 Right N, % 27 51.9% 31 51.7% Stone size (mm) Mean ± SD 22.5 2.0 22.6 2.5 0.839 Range 15 26 14 27 Stone location Pelvis N, % 29 55.8% 34 56.7% 0.987 Upper calyx N, % 7 13.5% 9 15.0% Middle calyx and pelvis N, % 8 15.4% 9 15.0% Pelvis &lower calyx N, % 8 15.4% 8 13.3% Hounsfield units Mean ± SD 953.6 341.8 953.1 337.2 0.994 Range 250 1700 250 1700 Table 3. Comparison of complications between studied groups. Without UAS With UAS P N = 52 N = 60 Intraoperative complication Mucosal injury Absent N, % 45 86.5% 52 86.7% 0.984 Present N, % 7 13.5% 8 13.3% Bleeding Absent N, % 43 82.7% 47 78.3% 0.563 Present N, % 9 17.3% 13 21.7% Failed Absent N, % 50 96.2% 56 93.3% 0.684 Present N, % 2 3.8% 4 6.7% Perforation Absent N, % 52 100% 59 98.3% 0.350 Present N, % 0 0.0% 1 1.7% False passage Absent N, % 50 96.2% 57 95.0% 0.768 Present N, % 2 3.8% 3 5.0% Converted to other procedure Absent N, % 50 96.2% 58 96.7% 0.884 Present N, % 2 3.8% 2 3.3% Post-operative complication Infection Absent N, % 47 90.4% 53 88.3% 0.726 Present N, % 5 9.6% 7 11.7% Fever Absent N, % 49 94.2% 56 93.3% 0.845 Present N, % 3 5.8% 4 6.7% Pain (loin or suprapubic) Absent N, % 32 61.5% 34 56.7% 0.601 Present N, % 20 38.5% 26 43.3% Hematuria Absent N, % 42 80.8% 45 75.0% 0.465 Present N, % 10 19.2% 15 25.0% Other complications Absent N, % 51 98.1% 58 96.7% 0.645 Present N, % 1 1.9% 2 3.3% Archivio Italiano di Urologia e Andrologia 2023; 95(3):11524 B.A. Fathi, A.A. Elgammal, T.A. Abouelgreed, O.M. Ghoneimy, A.Y. Aboelsaad, M.A. Alhefnawy 4 cerning operative time, stent duration and readmission (Table 4 and Figure 4). Hospital readmissions were due to fever and persistent pain. DISCUSSION Though PCNL was the first-line treatment of renal calculi greater than 2 cm, many studies demonstrated that RIRS can be a safer and effective alternative in managing renal stones 2 cm or more (13-15). According to a recent comprehensive study by De Coninck et al., UAS installation is not something that should be done routinely during RIRS. It may be used only in cases when gaining access to the ureter is chal- lenging, when treating patients with stones who have an elevated risk of infection complications, or in cases where visibility is poor owing to insufficient irrigation fluid outflow. The authors also draw the conclu- sion that, in the near future, the reasons for using a UAS might become less due to the advancement of smaller size single-use flexible digital ureteroscope (improved outflow by allowing more space between the ureteral wall and flexible uretero- scope), thulium fiber laser, and pressure- measuring instruments and integrated aspiration technology (16). In our study, we compared the utilization or not of UAS in treating renal stones 2 cm. Except for the fact that pre-stenting the ureter was much more common in the group that employed UAS, we found no statistically differences in the examined parameters between the two groups. Aboumarzouk et al. performed a meta-analysis and a com- prehensive review of studies using flexible ureteroscopy and laser lithotripsy to treat renal calculi more than 2 cm. Nine studies involving 445 patients reported an average SFR of around 93.7 percent. The mean number of operations per patient was 1.6. The average time of operations was 82.5 minutes. SFR for stones between 2 and 3 cm was considerably higher than those for stones > 3 cm (95.7 % vs 84.6 %; p = 0.01). The researchers concluded that laser lithotripsy performed using a flexible ureteroscope could be an alternative to PCNL for individuals with calculi ≥ 2 cm Table 4. Comparison of operative time and outcome between studied groups. Without UAS With UAS P N = 52 N = 60 Operative time (min) Operative time (min) Mean ± SD 81.4 4.5 82.8 13.6 0.469 Range 75 90 43 100 Outcome Stone free rate After the first procedure N, % 43 82.7% 54 90.0% 0.257 Another intervention 9 17.3% 6 10.0% Free after 2 sessions of URS N, % 5 55.6% 4 66.7% 0.667 Free after one SWL session Post-URS N, % 4 44.4% 2 33.3% 0.667 Stent duration (days) Mean ± SD 24.6 7.1 24.0 6.0 0.650 Range 15 45 15 45 Readmission Absent N, % 47 90.4% 56 93.3% 0.731 Present N, % 5 9.6% 4 6.7% Figure 3. Complications among studied groups. Figure 4. The stone-free rate among (A) with UAS and (B) without UAS. Archivio Italiano di Urologia e Andrologia 2023; 95(3):11524 5 The outcomes of flexible ureteroscopy for renal calculi of 2 cm or more with and without the use of ureteral access sheath (15). Scotland et al., in their study for treating large renal calculi (average dimension 2.75 cm) in 167 patients achieved a SFR in the first session of 57.1%, 90.2% in the second session and 94.0% in the third session. In their study, significant complications occurred in patients who had received UASs, which were utilized in 47% of cases. It was determined that either one or many sessions of ret- rograde ureteroscopic lithotripsy could be used to suc- cessfully treat large kidney calculi (17). In the present study, we found that intra and post-operative complica- tions were less in the group treated without UAS, although there was no significant difference. Also, the SFR after the first procedure was 82.7% in the group treated without UAS and 90.0% in the other group, although again the difference was not significant. Nine cases in the group treated without UAS (17.3%) and six cases in the other group (10.0%) required a second inter- vention. Meier et al., in their study on 5316 patients who underwent primary flexible ureteroscopy used the UAS in 1969 patients (37.7%) and found that those in whom a UAS was used had increased visits to the emergency department and hospitalization (p < 0.05) compared to those without UAS use. They concluded that using UAS is not without risk and UAS should be judiciously employed (18). Grasso et al. did not use a UAS in their study on managing 2 cm or more stones in the upper uri- nary tract. The study included 51 patients with 66 large upper urinary tract stones. The rate of success was 76% next to the initial procedure, 91% after a second session of flexible ureteroscopy and laser lithotripsy, and 93% after a third endoscopic session. In conclusion, they found that large upper urinary tract stones could be treat- ed appropriately and efficiently with flexible ureteroscopy and laser lithotripsy (19). El-Anany et al. performed a study that included thirty patients with a renal stone of more than 2 cm managed with either a semi-rigid ureteroscope or flexible ureteroscopy and laser lithotrip- sy without using the UAS. The success rate was 77% (23 of the 30 patients), with a negligible incidence of compli- cations. Of the other seven patients, three of them con- verted to PCNL and four to extracorporeal shock wave lithotripsy (ESWL). If there was a lot of debris remaining after fragmentation, they employed two ureteric catheters with “a 5 F catheter in the most dependent calyx and a 6 F catheter in the upper calyx” for constant irrigation (100 mL/h of saline with 80 mg/L of gentamicin). They deter- mined that a retrograde endoscopic approach employing laser lithotripsy was a secure and successful means of treating big renal calculi (20). Palmero et al. performed a retrospective review of 106 patients with renal calculi 2 cm or more who underwent RIRS with UAS in all cases. The average calculi size was 2.46 cm. The success rates was 73.6% (for a single procedure) and 93.4% for retreat- ment with a 6.7% postoperative minor complication rate. They concluded that for renal stones 2 cm or more, RIRS is a valid alternative to PCNL with few complications and a high success rate (21). Similarly, in a separate study by Al-Qahtani et al., on 120 patients with renal stones more than 2 cm, they achieved stone-free status in 58.5% after the first session, 87% after the second session, and 96.7% after the third session. They concluded that flexible ureteroscopy using a holmium laser is a successful and safe treatment with little morbidity. It could be an alter- native to PCNL, especially for stone burdens from 2 to 3 cm (22). Another recent study was performed by Huang et al. to treat renal stones 2 cm or greater. In 279 patients with a mean stone diameter of 26.5 mm SFR was 61.9% at the first, 82.9% at the second, and 89.5% at the third procedure. Fever was the most common complication, with a 15.1% overall complication rate. The conclusion was that RIRS could be utilized to treat large kidney stones (2 to 4 cm) with an acceptable com- plication rate and efficacy (23). This study has some lim- itations; the first is being retrospective in nature with selection bias. 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Retrograde ureteropyeloscopic treatment of 2 cm. or greater upper urinary tract and minor Staghorn calculi. J Urol. 1998; 160:346-351. 20. El-Anany FG, Hammouda HM, Maghraby HA, Elakkad MA. Retrograde ureteropyeloscopic holmium laser lithotripsy for large renal calculi. BJU International. 2001; 88:850-853. 21. Palmero JL, Castelló A, Miralles J, et al. Results of retrograde intrarenal surgery in the treatment of renal stones greater than 2 cm. Actas Urol Esp. 2014; 38:257-262. 22. Al-Qahtani SM, Gil-Deiz-de-Medina S, Traxer O. Predictors of clinical outcomes of flexible ureterorenoscopy with holmium laser for renal stone greater than 2 cm. Adv Urol. 2012; 2012:543537. 23. Huang JS, Xie J, Huang XJ, Yuan Q, et al. Flexible ureteroscopy and laser lithotripsy for renal stones 2 cm or greater: A single insti- tutional experience. Medicine. 2020; 99:e22704. Correspondence Basem A. Fathi, MD (Corresponding Author) basemhara@gmail.com; basemabdalla.8@azhar.edu.eg Ahmed A. Elgammal, MD aelgammal36@gmail.com Tamer A. Abouelgreed, MD dr_tamer_ali@yahoo.com; tamerali.8@azhar.edu.eg Osama M. Ghoneimy, MD elgendyosama787@gmail.com Department of Urology, Faculty of Medicine, Al-Azhar University, Cairo, Egypt Ahmed Y. Aboelsaad, MD aboelsaadurology@hotmail.com Department of Urology, Faculty of Medicine, Al-Azhar University, Damietta, Egypt Mohamed A. Alhefnawy, MD dr.mohamedalhefnawy@gmail.com Department of Urology, Faculty of Medicine, Benha University, Egypt Conflict of interest: The authors declare no potential conflict of interest.