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E33 Outcome of ureteroscopy for stone disease in patients with horseshoe kidney (HSK): Results from a systematic review of literature
thursday 5 september 2013 / european urology supplements 12 (2013) 29–68
of this study was to evaluate the outcomes and safety of RIRS, used either as a primary or secondary procedure, and to analyze factors predicting the stone-free rate (SFR). Material & Methods: A retrospective analysis was performed on data from patients who underwent RIRS over a 10-year period (2002–2012). Stone size was measured as the surface area and was calculated according to the EAU guidelines. In cases of multiple stones, the total stone burden was calculated as the sum of each stone size. Stone burden was then classified as ≤80 mm2 or >80 mm2 . RIRS was classified as primary procedure or secondary procedure (after failed extracorporeal shockwave lithotripsy or percutaneous nephrolithotripsy). Stone clearance was defined as a complete absence of stones or stones <4 mm, which were deemed insignificant on ultrasonography and plain radiography. Results: The overall SFR for renal stones treated with RIRS in our center was 55.4%, and the complication rate was 1.5%, which consisted of one case of sepsis. The only factor affecting SFR in this study was the indication for RIRS. When performed as a primary operation, RIRS showed a significantly better SFR (64.3%). The SFR for lower pole stones was only 44.4%. There were no statistically significant effects of stone burden, radioopacity, or combination with ureteral stones on SFR Conclusions: RIRS should be used as the primary treatment for renal stones whenever possible. E32 Modified technique of RIRS N. Joshi. NMC Specialty Hospital, Dept. of Urology, Al Ain, United Arab Emirates Introduction & Objectives: Retrograde IntraRenal Surgery is an established procedure. It is mainly used for removal of upper urinary stones. The procedure has many established advantages and is preferred due to its non invasiveness. In standard technique, 1. Operating surgeon handles both – flexible scope and camera – on his own. This makes maneuvering of the scope, targeting the stone and manipulating the stone very cumbersome and tiring. Leading to – Lengthy procedure, fatigue to the surgeon, non retrieval of stone and equipment breakage. 2. The camera does not stay in neutral position, making endo vision orientation difficult. 3. The scope is curved near the handle, which makes high chance of damage to the inner channel. Novel Approach: I have established a procedure by which all these issues are resolved. Material & Methods: The Cystoscopy Sheath is introduced in the bladder to nullify the urethral curvature in the male patient. Fluoroscopy is used at every step during the surgery. 6 Fr and 8 Fr Semi rigid ureterorenoscope are used to dilate the ureter under vision. This dilatation facilitates the introduction of the initial access sheath. Two guide wires are inserted in the ureter up to the kidney. The initial access sheath is inserted. The inner sheath and wire are removed together. The wire is never pushed from the tip of the scope. (1) The main modification of the technique is: the scope is held straight at every point. The 1st Assistant stabilizes the scope and maintains the camera alignment. The surgeon’s left hand does to & fro movement of scope or device manipulation. And the right hand does rotation & deflection movements of the scope. The 2nd Assistant catches the stone by a special basket. By keeping the camera stabilized, the endo orientation is never lost. By this method the inner channel stays straight, decreasing the chance of inner channel damage. The surgeon can sit on a chair to have full control of his movements and can easily concentrate on the procedure without getting fatigue or losing
41
the field of vision. Help of two assistants takes away the strain. Double channel Flexible scope has the advantage of non leakage of irrigation while working with a device. Exclusive channel for irrigation facilitates good flow of saline and provides clear visual field. The smaller the Laser – the better for the life of the scope. Smaller fiber does not decrease the time to fragment the stone. Laser fiber must be inserted gently and in a straight scope. (2) The laser tip should be just visible before flexing the scope to target the stone. Then advance the fiber to touch the stone and fire the laser. A specially designed basket catches stones very smoothly from the cup of the calyx. The double channel scope allows stone being held with a basket and laser inserted through another channel to fragment the stone. Care is taken not to fire the basket. If the basket is damaged, remove the whole assembly, chop off the tip of the basket and then withdraw it. If stone is not focused for grasping or lasing, saline is flushed by a syringe, to displace the stone in a proper position. At the end, DJ Stenting is done through a Rigid uretero scope. Results: 1. I did more than 130 cases of RIRS with one scope. 2. Time from starting the procedure to visualize the stone was on average 10 minutes. 3. The operating time reduced from average 3 hours to about 1.5 hour by this technique. 4. The scope’s channel got damaged once and was successfully repaired. 5. 5 cases needed a smaller diameter scope for smaller ureter size. 6. Stone clearance rate was 85%. Conclusions: Modified technique of RIRS makes the procedure easy, fast & cost effective. E33 Outcome of ureteroscopy for stone disease in patients with horseshoe kidney (HSK): Results from a systematic review of literature B.K. Somani1 , H. Ishii1 , A.V. Rawandale2 , O. Aboumarzouk3 , O. Traxer4 . 1 University Hospitals Southampton N H S Trust, Dept. of Urology, Southampton, United Kingdom; 2 Institute of Urology, Dept. of Urology, Dhule, India; 3 University Hospitals Wales, Dept. of Urology, Cardiff, United Kingdom; 4 Tenon University Hospital, Dept. of Urology, Paris, United Kingdom Introduction & Objectives: The management of urolithiasis in patients with horseshoe kidney (HSK) is difficult. Stone formation occurs in 1:5 patients with HSK due to impaired urinary drainage and infections. PCNL and lithotripsy can be medically contraindicated or technically challenging. We conducted a systematic review of literature to look at the role of ureteroscopy for stone management in these patients. Material & Methods: We searched MEDLINE, PubMed and the Cochrane Library from January 1990 to April 2013 for results of ureteroscopy and stone treatment in HSK patients. Inclusion criteria were all English language articles reporting on ureteroscopy in patients with HSK. Data was extracted on the outcomes and complications. Results: A total of 3 studies were identified during this period. Forty-one patients with HSK underwent flexible ureteroscopy and stone treatment. Of these 14 (34%) had prior lithotripsy, 8 (20%) had prior PCNL and 7 (17%) had prior open stone surgery. The mean age was 42 with a male:female ratio nearly 3:1. The mean stone size was 16 mm (range 3 to 35 mm). The mean operating time was 86 min with multiple stones seen in 15 patients. All 41 patients had a ureteral access sheath used and a flexible ureteroscopy and holmium laser fragmentation done. Thirty-two (78%) patients were stone free with a mean hospital stay of one day. Minor complications (Clavien I or II) were seen in 13 (32%) of which 6 had stent discomfort, 3 needed
42
thursday 5 september 2013 / european urology supplements 12 (2013) 29–68
intravenous antibiotics for <24 hours, 3 had haematuria of which 2 needed blood transfusion and one had pyelonephritis needing re-admission. There were no major complications found in the review. Conclusions: Retrograde stone treatment using ureteroscopy and lasertripsy in HSK patients can be performed with good stone clearance rate (although a second session is often necessary to completely clear the residual stones) but with a slightly higher complication rate. This procedure should therefore be done in high volume stone centre with an experienced stone surgeon/team. E34 Holmium laser clam cystolithotripsy of a giant stone through ileal Mitrofanoff stoma N.M. Mertziotis, D.K. Kozyrakis, E.B. Bogris. Mitera Hospital, Dept. of Urology, Athens, Greece Introduction & Objectives: We present a case of a holmium laser lithotripsy of a giant stone in a clam cystoplasty bladder with ileal Mitrofanoff stoma. Material & Methods: A 33-year-old patient with a history of several operations since the birth due to vesical exstrophy and epispadias currently with a clam ileo-sigmoid bladder and ileal mitrofanoff stoma, presented to outpatient of our clinic with reccurent urinary infections and difficulty to self catheterize himself. Retrograde neo urethro-cysto graphy revealed a stenosis of the ileal Mitrofanoff-ileal clam anastomosis and a large 5 cmx5 cm stone in a bifidus (dual compartment) bladder consisting of mixed ileal-sigmoid plasty. A holmium laser lithotripsy was performed through cystoscope prior dilatation of the anastomosis. Results: The whole procedure lasted 120 min and the patient was discharged the same day stone free with a foley catheter which was removed the 7th post operative day. After 6 months he is able to catheterize easily himself while the kub film showed no lithiasis. Conclusions: A holmium laser lithotripsy is a safe and efficient method for extremely large bladder stones even in complex cases. E35 The new surgical treatment method of staghorn urolithiasis in children B. Jurkiewicz1 , K. Jobs2 . 1 Childrens Hospital, Dept. of Pediatric Surgery, Warsaw, Poland; 2 Wojskowy Instytut Medyczny, Dept. of Pediatric Surgery, Warsaw, Poland Introduction & Objectives: Nephrolithiasis occurence in children is estimated for 1–3%. About 20% of them require endoscopic intervention. There are 3 basic treatment methods: ESWL, PCNL and URSL. Only in some cases of massive staghorn urolithiasis a traditional open surgery is justified. Objective: analysis of treatment results in patients with staghorn urolithiasis treated with innovative method combining traditional pyelolithotomy and endoscopic technique. Material & Methods: We performed retrospective analysis of treated children. In 2009–2012 120 children aged 3–15 years suffering from urolithiasis underwent medical treatment in surgical department. In 8.3% of them we recognized staghorn lithiasis: 8 unilateral, 2 bilateral. All of them suffered from recurrent urinary tract infections and lumbar region pain. All patients underwent abdominal ultrasound examination, plain abdominal X-ray and urography. In all cases calculi filled up renal pelvis and at least 2 calyces. All patients were surgically treated, one of them requiered urgent treatment because of urosepsis and complete blockade of urine outflow by staghorn calculus. All received preoperative antibiotics. Surgical procedure included pyelotomy, removal of stones from renal
pelvis by forceps under direct vision and endoscopy of the whole pelvis and each calyx by nephroscope. The presence of calculi required lithotripsy by ultrasound waves. Minor calculi were simultaneously removed by suction pump. After removing all stones DJ catheter was placed. Renal pelvis was stitched up in a typical way. In 3 cases Hynes–Anderson pyeloplasty was conducted. Results: 8 of 12 treated patients (66.6%) were completely stone free. Ultrasound examination showed residual fragments (app. 6–8 mm) in calyces of 4 (33.3%) patients. 3 of them were treated with ESWL and one expelled stones without medical intervention. One patient required transfusion of 1 unit of PRBCs. One patient was diagnosed with symptoms of urinary tract infection on the third day after surgery. Conclusions: Treatment of staghorn nephrolithiasis in children is a great challenge for surgeons. The presented method seems to be a good alternative to the traditional pyelocalycotomy and minimally invasive PCNL. Both mentioned methods require multiple incisions of renal parenchyma. There is also risk of bleeding and formation of parenchymal scars. The presented method enables to remove calculi from pyelocalycal system very precisely, without the necessity of renal parenchyma incision. The combination of traditional open surgery with endoscopy of calyces and lithotripsy is in our opinion a good alternative to staghorn calculi treatment in children. E36 Transurethral contact uretrolithotripsy T. Nazarov, S. Magidov, M. Ahmedov. Northwestern State Medical University, Dept. of Urology, Saint-Petersburg, Russia Introduction & Objectives: Ureterolithiasis is the most widespread reason of obstruction ureters. Now endoscopic methods of removal of ureteral stones are the most widespread and effective. Material & Methods: For the past of 5 years in clinics of faculty 320 endoscopic contact uretrolithotripsies have been executed. Age range of the patients was from 23 to 78 years, 197 men and 123 women. 281 (87.8%) are delivered to the patient inclinics of faculty under emergency indications. At complex inspection following localization stones in ureter (by the sizes from 0.6 up to 1.5 cm) is established: in 189 patients of the top and average third, in 131 patients in the bottom third. For contact uretrolithotripsy were applied the ultrasonic device and pneumatic lithotripter. Contact uretrolithotripsy was spent on a background of antibacterial therapy by preparations of a wide spectrum of action under intravenous neuroleptanalgesia. Results: Duration of operation varied from 10 to 50 minutes and depended on complexity of the cases. In 279 (87.1%) patients, outflow from a kidney by a fragmentation and was possible to restore decompositions of a stone, and 41 (12.9%) to the patient on a background of partial destruction stones last moved in calyces – pelvis system, and in the scheduled order by it has been executed successful remote lithotripsy. Conclusions: Contact uretrolithotripsy is an effective and smallinvasive method of treatment of ureterolithiasis. E37 Does ureteral pre-stenting facilitate retrograde intrarenal surgery (RIRS)? F. Longo1 , G. Zanetti2 , A. Trinchieri3 , M. Delor1 , E. Montanari1 . 1 San Paolo Hospital, Dept. of Urology, Milano, Italy; 2 Desio and Vimercate Hospital, Dept. of Urology, Vimercate, Italy; 3 Lecco Hospital, Dept. of Urology, Lecco, Italy Introduction & Objectives: Flexible ureterorenoscopy has an important role in the endourologist’s armamentarium for the renal stone treatment. Ureteral Stenting before RIRS is often performed in order to passively enlarge the ureter and
of this study was to evaluate the outcomes and safety of RIRS, used either as a primary or secondary procedure, and to analyze factors predicting the stone-free rate (SFR). Material & Methods: A retrospective analysis was performed on data from patients who underwent RIRS over a 10-year period (2002–2012). Stone size was measured as the surface area and was calculated according to the EAU guidelines. In cases of multiple stones, the total stone burden was calculated as the sum of each stone size. Stone burden was then classified as ≤80 mm2 or >80 mm2 . RIRS was classified as primary procedure or secondary procedure (after failed extracorporeal shockwave lithotripsy or percutaneous nephrolithotripsy). Stone clearance was defined as a complete absence of stones or stones <4 mm, which were deemed insignificant on ultrasonography and plain radiography. Results: The overall SFR for renal stones treated with RIRS in our center was 55.4%, and the complication rate was 1.5%, which consisted of one case of sepsis. The only factor affecting SFR in this study was the indication for RIRS. When performed as a primary operation, RIRS showed a significantly better SFR (64.3%). The SFR for lower pole stones was only 44.4%. There were no statistically significant effects of stone burden, radioopacity, or combination with ureteral stones on SFR Conclusions: RIRS should be used as the primary treatment for renal stones whenever possible. E32 Modified technique of RIRS N. Joshi. NMC Specialty Hospital, Dept. of Urology, Al Ain, United Arab Emirates Introduction & Objectives: Retrograde IntraRenal Surgery is an established procedure. It is mainly used for removal of upper urinary stones. The procedure has many established advantages and is preferred due to its non invasiveness. In standard technique, 1. Operating surgeon handles both – flexible scope and camera – on his own. This makes maneuvering of the scope, targeting the stone and manipulating the stone very cumbersome and tiring. Leading to – Lengthy procedure, fatigue to the surgeon, non retrieval of stone and equipment breakage. 2. The camera does not stay in neutral position, making endo vision orientation difficult. 3. The scope is curved near the handle, which makes high chance of damage to the inner channel. Novel Approach: I have established a procedure by which all these issues are resolved. Material & Methods: The Cystoscopy Sheath is introduced in the bladder to nullify the urethral curvature in the male patient. Fluoroscopy is used at every step during the surgery. 6 Fr and 8 Fr Semi rigid ureterorenoscope are used to dilate the ureter under vision. This dilatation facilitates the introduction of the initial access sheath. Two guide wires are inserted in the ureter up to the kidney. The initial access sheath is inserted. The inner sheath and wire are removed together. The wire is never pushed from the tip of the scope. (1) The main modification of the technique is: the scope is held straight at every point. The 1st Assistant stabilizes the scope and maintains the camera alignment. The surgeon’s left hand does to & fro movement of scope or device manipulation. And the right hand does rotation & deflection movements of the scope. The 2nd Assistant catches the stone by a special basket. By keeping the camera stabilized, the endo orientation is never lost. By this method the inner channel stays straight, decreasing the chance of inner channel damage. The surgeon can sit on a chair to have full control of his movements and can easily concentrate on the procedure without getting fatigue or losing
41
the field of vision. Help of two assistants takes away the strain. Double channel Flexible scope has the advantage of non leakage of irrigation while working with a device. Exclusive channel for irrigation facilitates good flow of saline and provides clear visual field. The smaller the Laser – the better for the life of the scope. Smaller fiber does not decrease the time to fragment the stone. Laser fiber must be inserted gently and in a straight scope. (2) The laser tip should be just visible before flexing the scope to target the stone. Then advance the fiber to touch the stone and fire the laser. A specially designed basket catches stones very smoothly from the cup of the calyx. The double channel scope allows stone being held with a basket and laser inserted through another channel to fragment the stone. Care is taken not to fire the basket. If the basket is damaged, remove the whole assembly, chop off the tip of the basket and then withdraw it. If stone is not focused for grasping or lasing, saline is flushed by a syringe, to displace the stone in a proper position. At the end, DJ Stenting is done through a Rigid uretero scope. Results: 1. I did more than 130 cases of RIRS with one scope. 2. Time from starting the procedure to visualize the stone was on average 10 minutes. 3. The operating time reduced from average 3 hours to about 1.5 hour by this technique. 4. The scope’s channel got damaged once and was successfully repaired. 5. 5 cases needed a smaller diameter scope for smaller ureter size. 6. Stone clearance rate was 85%. Conclusions: Modified technique of RIRS makes the procedure easy, fast & cost effective. E33 Outcome of ureteroscopy for stone disease in patients with horseshoe kidney (HSK): Results from a systematic review of literature B.K. Somani1 , H. Ishii1 , A.V. Rawandale2 , O. Aboumarzouk3 , O. Traxer4 . 1 University Hospitals Southampton N H S Trust, Dept. of Urology, Southampton, United Kingdom; 2 Institute of Urology, Dept. of Urology, Dhule, India; 3 University Hospitals Wales, Dept. of Urology, Cardiff, United Kingdom; 4 Tenon University Hospital, Dept. of Urology, Paris, United Kingdom Introduction & Objectives: The management of urolithiasis in patients with horseshoe kidney (HSK) is difficult. Stone formation occurs in 1:5 patients with HSK due to impaired urinary drainage and infections. PCNL and lithotripsy can be medically contraindicated or technically challenging. We conducted a systematic review of literature to look at the role of ureteroscopy for stone management in these patients. Material & Methods: We searched MEDLINE, PubMed and the Cochrane Library from January 1990 to April 2013 for results of ureteroscopy and stone treatment in HSK patients. Inclusion criteria were all English language articles reporting on ureteroscopy in patients with HSK. Data was extracted on the outcomes and complications. Results: A total of 3 studies were identified during this period. Forty-one patients with HSK underwent flexible ureteroscopy and stone treatment. Of these 14 (34%) had prior lithotripsy, 8 (20%) had prior PCNL and 7 (17%) had prior open stone surgery. The mean age was 42 with a male:female ratio nearly 3:1. The mean stone size was 16 mm (range 3 to 35 mm). The mean operating time was 86 min with multiple stones seen in 15 patients. All 41 patients had a ureteral access sheath used and a flexible ureteroscopy and holmium laser fragmentation done. Thirty-two (78%) patients were stone free with a mean hospital stay of one day. Minor complications (Clavien I or II) were seen in 13 (32%) of which 6 had stent discomfort, 3 needed
42
thursday 5 september 2013 / european urology supplements 12 (2013) 29–68
intravenous antibiotics for <24 hours, 3 had haematuria of which 2 needed blood transfusion and one had pyelonephritis needing re-admission. There were no major complications found in the review. Conclusions: Retrograde stone treatment using ureteroscopy and lasertripsy in HSK patients can be performed with good stone clearance rate (although a second session is often necessary to completely clear the residual stones) but with a slightly higher complication rate. This procedure should therefore be done in high volume stone centre with an experienced stone surgeon/team. E34 Holmium laser clam cystolithotripsy of a giant stone through ileal Mitrofanoff stoma N.M. Mertziotis, D.K. Kozyrakis, E.B. Bogris. Mitera Hospital, Dept. of Urology, Athens, Greece Introduction & Objectives: We present a case of a holmium laser lithotripsy of a giant stone in a clam cystoplasty bladder with ileal Mitrofanoff stoma. Material & Methods: A 33-year-old patient with a history of several operations since the birth due to vesical exstrophy and epispadias currently with a clam ileo-sigmoid bladder and ileal mitrofanoff stoma, presented to outpatient of our clinic with reccurent urinary infections and difficulty to self catheterize himself. Retrograde neo urethro-cysto graphy revealed a stenosis of the ileal Mitrofanoff-ileal clam anastomosis and a large 5 cmx5 cm stone in a bifidus (dual compartment) bladder consisting of mixed ileal-sigmoid plasty. A holmium laser lithotripsy was performed through cystoscope prior dilatation of the anastomosis. Results: The whole procedure lasted 120 min and the patient was discharged the same day stone free with a foley catheter which was removed the 7th post operative day. After 6 months he is able to catheterize easily himself while the kub film showed no lithiasis. Conclusions: A holmium laser lithotripsy is a safe and efficient method for extremely large bladder stones even in complex cases. E35 The new surgical treatment method of staghorn urolithiasis in children B. Jurkiewicz1 , K. Jobs2 . 1 Childrens Hospital, Dept. of Pediatric Surgery, Warsaw, Poland; 2 Wojskowy Instytut Medyczny, Dept. of Pediatric Surgery, Warsaw, Poland Introduction & Objectives: Nephrolithiasis occurence in children is estimated for 1–3%. About 20% of them require endoscopic intervention. There are 3 basic treatment methods: ESWL, PCNL and URSL. Only in some cases of massive staghorn urolithiasis a traditional open surgery is justified. Objective: analysis of treatment results in patients with staghorn urolithiasis treated with innovative method combining traditional pyelolithotomy and endoscopic technique. Material & Methods: We performed retrospective analysis of treated children. In 2009–2012 120 children aged 3–15 years suffering from urolithiasis underwent medical treatment in surgical department. In 8.3% of them we recognized staghorn lithiasis: 8 unilateral, 2 bilateral. All of them suffered from recurrent urinary tract infections and lumbar region pain. All patients underwent abdominal ultrasound examination, plain abdominal X-ray and urography. In all cases calculi filled up renal pelvis and at least 2 calyces. All patients were surgically treated, one of them requiered urgent treatment because of urosepsis and complete blockade of urine outflow by staghorn calculus. All received preoperative antibiotics. Surgical procedure included pyelotomy, removal of stones from renal
pelvis by forceps under direct vision and endoscopy of the whole pelvis and each calyx by nephroscope. The presence of calculi required lithotripsy by ultrasound waves. Minor calculi were simultaneously removed by suction pump. After removing all stones DJ catheter was placed. Renal pelvis was stitched up in a typical way. In 3 cases Hynes–Anderson pyeloplasty was conducted. Results: 8 of 12 treated patients (66.6%) were completely stone free. Ultrasound examination showed residual fragments (app. 6–8 mm) in calyces of 4 (33.3%) patients. 3 of them were treated with ESWL and one expelled stones without medical intervention. One patient required transfusion of 1 unit of PRBCs. One patient was diagnosed with symptoms of urinary tract infection on the third day after surgery. Conclusions: Treatment of staghorn nephrolithiasis in children is a great challenge for surgeons. The presented method seems to be a good alternative to the traditional pyelocalycotomy and minimally invasive PCNL. Both mentioned methods require multiple incisions of renal parenchyma. There is also risk of bleeding and formation of parenchymal scars. The presented method enables to remove calculi from pyelocalycal system very precisely, without the necessity of renal parenchyma incision. The combination of traditional open surgery with endoscopy of calyces and lithotripsy is in our opinion a good alternative to staghorn calculi treatment in children. E36 Transurethral contact uretrolithotripsy T. Nazarov, S. Magidov, M. Ahmedov. Northwestern State Medical University, Dept. of Urology, Saint-Petersburg, Russia Introduction & Objectives: Ureterolithiasis is the most widespread reason of obstruction ureters. Now endoscopic methods of removal of ureteral stones are the most widespread and effective. Material & Methods: For the past of 5 years in clinics of faculty 320 endoscopic contact uretrolithotripsies have been executed. Age range of the patients was from 23 to 78 years, 197 men and 123 women. 281 (87.8%) are delivered to the patient inclinics of faculty under emergency indications. At complex inspection following localization stones in ureter (by the sizes from 0.6 up to 1.5 cm) is established: in 189 patients of the top and average third, in 131 patients in the bottom third. For contact uretrolithotripsy were applied the ultrasonic device and pneumatic lithotripter. Contact uretrolithotripsy was spent on a background of antibacterial therapy by preparations of a wide spectrum of action under intravenous neuroleptanalgesia. Results: Duration of operation varied from 10 to 50 minutes and depended on complexity of the cases. In 279 (87.1%) patients, outflow from a kidney by a fragmentation and was possible to restore decompositions of a stone, and 41 (12.9%) to the patient on a background of partial destruction stones last moved in calyces – pelvis system, and in the scheduled order by it has been executed successful remote lithotripsy. Conclusions: Contact uretrolithotripsy is an effective and smallinvasive method of treatment of ureterolithiasis. E37 Does ureteral pre-stenting facilitate retrograde intrarenal surgery (RIRS)? F. Longo1 , G. Zanetti2 , A. Trinchieri3 , M. Delor1 , E. Montanari1 . 1 San Paolo Hospital, Dept. of Urology, Milano, Italy; 2 Desio and Vimercate Hospital, Dept. of Urology, Vimercate, Italy; 3 Lecco Hospital, Dept. of Urology, Lecco, Italy Introduction & Objectives: Flexible ureterorenoscopy has an important role in the endourologist’s armamentarium for the renal stone treatment. Ureteral Stenting before RIRS is often performed in order to passively enlarge the ureter and