***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    Input: In an attempt to assess the usefulness of a ureteral stent in facilitating disintegration of obstructed proximal ureteral stone  with extracorporeal shock wave lithotripsy ( ESWL ) , a prospect i ve r and omized study on 120 patients with ultrasonic evidence of hydronephrosis whose stone sizes were greater than 1.0 x 0.6 cm on KUB film and located above the level of L5 were allocated into three distinct treatment strategies : group 1 : in situ without stone manipulation ; group 2 : bypass stones with stent , and group 3 : placement of a catheter below stone with continuous saline irrigation . Of 77 patients , 26 , 27 and 24 in each group , followed up for a period of 6 months with sufficient data for analysis , the stone-free rates were 76.9 , 59.3 and 62.5 % , respectively . The average number of shock waves delivered to accomplish a stone-free state were 3,245 , 3,250 and 3,880 for individual groups and the comparisons among them were statistically insignificant ( p 's > 0.1 ) . ESWL retreatment was common , being 33.3 , 29.4 and 43.8 % , respectively . Hydronephrosis has a major impact on the outcome of ESWL treatment , as more stone-free cases were found in the mildly hydronephrotic category than in the severer counterparts . About 90 % of cases who finally were stone-free , passed all their stone fragments within 28 days . Ancillary procedures were needed in 13 ( 16.9 % ) , 7 received ureterolithotomy , whilst 6 were removed of their stones by ureteroscopy Objectives Since introduction of extracorporeal shockwave lithotripsy ( ESWL ) in treating patients with urinary tract stones in our clinic for the first time in our city Aden 5 years ago , we stented  all patients with kidney stone > 1 cm routinely before the procedure . Our aim of this study is to compare symptoms and complications of patients with and without stenting . Patients and methods In 2003 , 120 patients with renal stone(s ) amenable to ESWL management were prospect ively treated in two groups : stented ( 60 patients ) and unstented ( 60 patients ) . All patients were admitted for 48 h after ESWL and then followed for 3 months after discharge by the same treating group of doctors . Patients were followed-up radiographically to assess stone-free rate after 1 and 3 months . Results There was no statistical difference in flank or abdominal pain , nausea , vomiting , transient hematuria , temperature or use of analgesics on the first and second day after ESWL in the stented or unstented group . Fifty-one patients ( 85 % ) of stented group complained of side effects attributable to stent including urinary frequency and urgency , bladder pain and hematuria with urination , which in all patients but 3 of them were treated as out patient and one of the unstented group , who were readmitted because of mild to severe pain , fever , and chills . In all stented patients , we removed the stents after 2 weeks ; except in readmitted patients where it was removed earlier . Plain X-ray film was done for all patients after one and 3 months . Eight patients with stents ( 6.7 % ) had > 5 mm residual fragments . In these patients second ESWL session was necessary . Three months stone-free rate was 88 % in stented and 91 % in unstented group , respectively . Conclusion The use of double-J stents prior to ESWL treatment is not beneficial OBJECTIVES To prospect ively evaluate the role of double J ( DJ ) stent in enhancing the passage of fragments in patients undergoing extracorporeal shockwave lithotripsy ( SWL ) for renal stones with diameters less than 2.5 cm . METHODS Between November 2005 and January 2007 , 38 patients with an average age of 47.05 years ( range 16 - 73 ) were included and underwent SWL for renal stones . The inclusion criteria were radio-opaque renal stone not located in the lower pole , complete disintegeration of the stone , normal renal function , no metabolic abnormalities , no major renal abnormalities and no symptomatic urinary tract infection . The patients were r and omized to either a stented ( 11 patients ) or stentless ( 27 patients ) group . The average stone diameters in stentless and stented groups were 1.54 cm and 1.77 cm , respectively ( p > 0.05 ) . Double J stent was removed when there was no further passage of the fragments for 6 weeks after stone disintegration . All patients were given non-steroidal anti-inflammatory drugs for one week after ESWL treatment . Stone passage and the data of DJ were determined with plain X-ray of the urinary tract ( UTP ) . The severity of lower urinary tract symptoms , loin pain and the need for intravenous or intramuscular analgesics were recorded . RESULTS The overall stone-free rate at 3 months was 92.1 % . Two patients in the stented and one patient in the stentless group were partially free of stones . Steinstrasse were observed in two patients ( 5.3 % ) ; one patient in the stentless group and another one after the removal of DJ stent . Only one patient in the stented group had severe lower urinary tract symptoms which responded neither to oral nor to other forms of analgesics , and therefore DJ stent was removed . The remaining patients were in no need for analgesics other than the oral therapy . CONCLUSION Placement of DJ stent for the purpose of improving free stone rate or enhancing the passage of the fragments during SWL is unnecessary in renal stone with diameters less than 2.5 cm . However , further prospect i ve trials should be design ed to define the criteria for stented SWL Ureteral stents reduce complications after extracorporeal shock wave lithotripsy ( ESWL * ) and contribute to successful stone passage . However , some reports note complications that are attributed to indwelling ureteral stents . We r and omized 64 patients with large renal calculi ( stone burden more than 200 mm.2 ) for in situ treatment or treatment with a prophylactically inserted stent .  We used a 6Ch round stent with single-coiled ends or a triangular shaped stent with double-coiled ends . Patients were treated with a Siemens Lithostar lithotriptor . After 3 months we evaluated the results of treatment and post-ESWL morbidity . Of the in situ group ( 23 patients ) treatment complications consisted of fever in 3 , pyelonephritis in 1 and steinstrasse in 3 . After 3 months 8 patients ( 35 % ) were free of stones . Of the stented population ( 41 patients ) treatment complications consisted of fever in 7 , pyelonephritis in 1 , steinstrasse in 6 and bladder discomfort in almost half of the patients . Stent calcification and stent migration were also seen in 7 and 10 patients , respectively . Calcified stents had been in situ longer than noncalcified stents . The round stents migrated and calcified more often than the more rigid triangular stents . After 3 months 18 of the stented patients were stone-free ( 44 % ) . We conclude that ureteral stents do not reduce post-ESWL complications . They are clearly associated with morbidity and do not improve stone passage markedly . Therefore , patients with a stone burden of more than 200 mm.2 should be treated in situ without auxiliary stenting PURPOSE We determine endourological practice patterns among American urologists for the management of distal ureteral calculi , ureteropelvic junction obstruction , staghorn calculi and the use of ureteral stents with extracorporeal shock wave lithotripsy ( ESWLdagger ) . MATERIAL S AND METHODS Surveys were mailed by the United States postal service to 1,000 American urologists selected r and omly from the American Urological Association membership roster . The same survey was sent via the Internet to 3,065 American urologists with an electronic mail address listed in the roster . RESULTS Responses were received from 1,029 urologists ( postal 601 , Internet 428 ) .  Ureteroscopy  was the preferred treatment for all distal ureteral calculi less than or equal to 10 mm . Acucisedouble dagger endopyelotomy  was the most frequently selected therapy for adults with ureteropelvic junction obstruction ( 50.3 % , 514 of 1,022 ) .  Open pyeloplasty  was recommended by a significantly greater percentage of urologists in practice longer than 15 years compared with the remaining survey respondents ( 166 of 485 , 34.2 % versus 92 of 427 , 21.5 % ) . For patients with renal pelvic stones 10 , 15 or 20 mm . who are treated with ESWL routine stent placement  was preferred by 25.3 % ( 259 of 1,022 ) , 57.1 % ( 584 of 1,022 ) and 87.1 % ( 888 of 1 , 019 ) of urologists , respectively .  Percutaneous nephrolithotomy  was preferred for patients with staghorn calculi by 80.5 % ( 828 of 1,028 ) of survey respondents . CONCLUSIONS Most urologists follow the American Urological Association practice guidelines for patients with distal ureteral calculi and staghorn stones . There is a significant difference of opinion regarding the use of stents with ESWL . No clear consensus has been reached concerning the management of adults with ureteropelvic junction obstruction . These data may be useful in design ing physician education programs and /or future investigations to help define st and ard treatment practice s for urological diseases PURPOSE Routine use of ureteral stents before extracorporeal shock wave lithotripsy of kidney stones between 10 and 20 mm . is controversial . We conducted a prospect i ve r and omized clinical trial to evaluate the outcome of ureteral stents for treating solitary kidney stones between 10 and 20 mm . or solitary proximal ureteral stones less than 20 mm . with shock wave lithotripsy . MATERIAL S AND METHODS A total of 97 patients who met the aforementioned criteria were r and omized between March 1994 to July 1997 into group 1-no stent , group 2-a  4.7Fr multi-length stent and group 3-a 7Fr multi-length stent . The patients were treated with the Dornier HM3 lithotriptor ( Dornier Medical Systems , Inc. , Marietta , Georgia ) and monitored for stone-free rate , number of days lost from work , number of patients requiring rehospitalization , emergency room visits , irritative voiding symptom score and pain symptom score . RESULTS Objective outcome was obtained from 91 patients based on a followup of at least 3 months . The overall stone-free rate was 80 % , with a re-treatment rate of 7 % . The number of days lost from work was approximately 2 , with no significant differences among individual groups or subgroups . The hospitalization rate and number of emergency room visits in group 1 ( 22 % ) were statistically higher compared to groups 2 ( 7 % ) and 3 ( 7 % ) . The irritative voiding symptom score was statistically higher in the stented groups 2 and 3 compared to the nonstented group 1 . CONCLUSIONS Although ureteral stents are associated with more irritative symptoms , their use result ed in fewer hospital readmissions and emergency room visits compared to when no stent was used to treat solitary kidney stones of 10 to 20 mm . or solitary proximal ureteral stones less than 20 mm . Size 4.7Fr stents may be preferable over 7Fr stents when used in conjunction with shock wave lithotripsy Double-pigtail stents are placed commonly in patients before extracorporeal shock wave lithotripsy to prevent ureteral obstruction from steinstrasse . The use of double-pigtail stents in lithotripsy patients with a moderate stone burden was studied in a prospect i ve r and omized trial . Patients with unilateral renal stone(s ) with at least 1 diameter between 7 and 25 mm . were eligible for the study . Fifty patients were r and omized to a control or stented group .  Double-pigtail stents with an attached suture were placed immediately before extracorporeal shock wave lithotripsy in the stented group . Stents were removed by the patients 1 week after lithotripsy . A survey on pain and associated symptoms was completed by patients at 1 and 14 days after treatment . There was no statistical difference in flank or abdominal pain , nausea , vomiting , temperature or use of analgesics at 1 and 14 days after extracorporeal shock wave lithotripsy in the control and stented groups . All patients in the stented groups complained of side effects attributable to the stent including urinary frequency and urgency , bladder pain , hematuria and flank pain with urination . Of 25 patients with stents 7 ( 27 % ) had early removal because of severe irritation , early migration or accidental removal . Among the patients with follow-up x-rays 1 month after treatment 17 of 21 ( 81 % ) in the control group and 12 of 19 ( 63 % ) in the stented group showed no evidence of remaining stones . The use of double-pigtail stents is not beneficial in patients with a moderate stone burden . Double-pigtail stents are associated with considerable patient 
    Output:
    
The systematic review suggested significant advantages of stenting before extracorporeal shock wave lithotripsy compared to in situ extracorporeal shock wave lithotripsy in terms of Steinstrasse .
However , stenting did not benefit stone-free rate and auxiliary treatment after extracorporeal shock wave lithotripsy , and it induced more lower urinary tract symptoms .