***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: PURPOSE A prospect i ve r and omized controlled trial was performed to determine whether stents may be eliminated after uncomplicated ureteroscopic lithotripsy for ureteral stones . MATERIAL S AND METHODS A total of 58 patients underwent uncomplicated ureteroscopic intracorporeal lithotripsy .  After stone fragmentation patients were r and omized to a  nonstented ( 29 ) or a stented ( 29 ) treatment group .  Intracorporeal lithotripsy was performed with the holmium laser in 57 cases and by electrohydraulic lithotripsy in 1 without balloon dilation or the extraction of stone fragments . Patients were followed 1 , 6 and 12 weeks postoperatively . In stented cases the stent was removed at 1 week . Outcome measures included postoperative symptoms assessed with a visual analog scale , postoperative analgesic requirements , complications and the stone-free rate . RESULTS At 1 week the symptoms of flank pain , abdominal pain , dysuria and frequency were significantly greater in the stented group ( p < 0.005 ) . There were no differences in symptoms in the groups at subsequent followup visits . There was no difference in treatment groups in terms of the amount of analgesic required in the recovery room or during 1 week after ureteroscopy . Similarly there was no difference in the number of patients requiring antiemetics . One patient in the stented group required hospitalization for genitourinary sepsis and 1 patient in the nonstented group visited the emergency room for postoperative vomiting . The stone-free rate was 100 % in each group . CONCLUSIONS These results demonstrate that after ureteroscopic intracorporeal lithotripsy with the holmium laser patients with a stent have significantly greater irritative and painful symptoms than those without a stent in the early postoperative period . There was no difference in nonstented and stented ureteroscopy with respect to complications or stone-free status . Therefore , we believe that routine stenting after ureteroscopic intracorporeal lithotripsy with the holmium laser is not required as long as the procedure is uncomplicated and performed without balloon dilation of the ureteral orifice Retro grade calculus migration during ureteroscopic lithotripsy remains a problem in 5–40 % of cases . We assessed the safety and efficacy of the Stone Cone device , in comparison with the st and ard flat wire basket . A total of 56 consecutive patients with ureteral calculi , suitable for ureteroscopic extraction and /or lithotripsy , where included in this prospect i ve study . Patients were r and omly allocated into two groups . In group A ( 30 patients ) , we used the Stone Cone , while in group B ( 26 patients ) we used the st and ard flat wire basket . The Stone Cone was placed through a cystoscope under fluoroscopic guidance , or when necessary under direct ureteroscopic control . Whenever necessary , intracorporeal electrohydraulic lithotripsy took place in both groups . Statistical significance was assessed by the paired t-test . The mean operative time was 48.5 min in group A , and 42.4 min in group B. Intact calculus extraction was possible in 16.6 % in group A , and in 7.6 % in group B ( P<0.01 ) . Retro grade stone migration was revealed in 23 % in group B only ( P<0.001 ) . Also , residual fragments > 3 mm were recorded in 30.7 % in group B only ( P<0.001 ) . None of the patients in group A required auxiliary procedures , in contrary to 23 % in group B ( P<0.001 ) . No major complications were recorded in group A , while in group B a case of major ureteral mucosal abrasion was recorded . The Stone Cone is safe and efficient in preventing retro grade stone migration and in minimizing residual fragments during ureteroscopic lithotripsy in comparison with the flat wire basket PURPOSE We present the first r and omized clinical study using BackStop , a novel reverse thermosensitive water-soluble polymer that is dispensed above the stone(s ) and temporarily occludes the ureter to prevent retropulsion of stone fragments during ureteroscopic lithotripsy . After fragmentation is completed and concretions are extracted , conventional irrigation with saline dissolves the polymer , which is then flushed out . MATERIAL S AND METHODS A total of 68 subjects with a single stone in the proximal ureter and an indication for ureteroscopic lithotripsy were enrolled in this prospect i ve , r and omized , single-blind , controlled , multisite clinical study . Each subject was r and omly assigned to the BackStop group ( 34 ) or the control group ( 34 with no antiretropulsion device ) . For subjects in the experimental group BackStop was dispensed into the ureter above the stone using a 3Fr or 5Fr catheter . Ureteroscopic lithotripsy was performed in all subjects using pneumatic or laser energy . Measured end points included the retropulsion rate , the need for subsequent procedures , the stone-free rate at followup , the occurrence of adverse events and ureteral occlusion , if any , and post-stone fragmentation and extraction . RESULTS Subjects r and omized to the BackStop group experienced a statistically significant ( p = 0.0002 ) lower rate of retropulsion ( 8.8 % , 3 of 34 ) vs the control group ( 52.9 % , 18/34 ) . There were no adverse events in the BackStop group and BackStop was successfully dissolved in every subject , result ing in a patent ureter . CONCLUSIONS BackStop appears to be a novel , safe and effective means of preventing stone fragment retropulsion during ureteroscopic lithotripsy for the management of ureteral stones OBJECTIVES To evaluate our experience in treating 155 patients with upper urinary tract calculi ureteroscopically . The treatment of urinary calculi has remained the most frequent application of ureteroscopy . Miniaturization of semirigid and flexible ureteroscopes has permitted easier access to calculi throughout the urinary tract . METHODS Ureteroscopic stone treatment was attempted in 155 patients with upper urinary tract calculi between November 1995 and March 1997 . Fifty-nine ( 38.1 % ) patients had renal calculi , 82 ( 52.9 % ) ureteral , and 14 ( 9 % ) had both renal and ureteral calculi . Both semirigid and flexible ureteroscopes were used for treatment ( rigid alone in 21 [ 13.5 % ] , flexible in 64 [ 41.3 % ] , and both rigid and flexible in 70 [ 45.2 % ] patients ) . Lithotripsy was required in 122 ( 79 % ) of the patients . The holmium : yttrium-aluminum-garnet laser was used in 113 ( 92.6 % ) of these patients . RESULTS All patients with ureteral calculi ( 29 proximal , 19 mid , and 34 distal ) were successfully cleared after one endoscopic procedure except for 1 patient with a proximal ureteral calculus who had a 4-mm residual fragment in the kidney . Of the 59 patients with renal calculi , 47 ( 79.7 % ) were totally clear of stones 1 month after treatment . The remaining 12 ( 20.3 % ) patients had evidence of residual calculi 3 to 4 mm or less in diameter . In patients with combined renal and ureteral calculi , 1 1 of 14 ( 78.6 % ) were rendered stone free . The remaining 3 ( 21.4 % ) patients had evidence of residual calculi 4 mm in diameter . Overall , 95 % of the patients were treated in an outpatient setting . Morbidity was low , with no evidence of stricture . CONCLUSIONS Ureteroscopy and laser lithotripsy in experienced h and s are a safe and reliable method for the treatment of ureteral and even intrarenal calculi OBJECTIVE A series of experiments were conducted to test the hypothesis that the mechanism of holmium : YAG lithotripsy is photothermal . METHODS AND RESULTS To show that holmium : YAG lithotripsy requires direct absorption of optical energy , stone loss was compared for 150 J Ho : YAG lithotripsy of calcium oxalate monohydrate ( COM ) stones for hydrated stones irradiated in water ( 17+/-3 mg ) and hydrated stones irradiated in air ( 25+/-9 mg ) v dehydrated stones irradiated in air ( 40+/-12 mg ) ( P < 0.001 ) . To show that Ho : YAG lithotripsy occurs prior to vapor bubble collapse , the dynamics of lithotripsy in water and vapor bubble formation were documented with video flash photography . Holmium : YAG lithotripsy began at 60 microsec , prior to vapor bubble collapse . To show that Ho : YAG lithotripsy is fundamentally related to stone temperature , cystine , and COM mass loss was compared for stones initially at room temperature ( approximately 23 degrees C ) v frozen stones ablated within 2 minutes after removal from the freezer . Cystine and COM mass losses were greater for stones starting at room temperature than cold ( P < or = 0.05 ) . To show that Ho : YAG lithotripsy involves a thermochemical reaction , composition analysis was done before and after lithotripsy . Postlithotripsy , COM yielded calcium carbonate ; cystine yielded cysteine and free sulfur ; calcium hydrogen phosphate dihydrate yielded calcium pyrophosphate ; magnesium ammonium phosphate yielded ammonium carbonate and magnesium carbonate ; and uric acid yielded cyanide . To show that Ho : YAG lithotripsy does not create significant shockwaves , pressure transients were measured during lithotripsy using needle hydrophones . Peak pressures were < 2 bars . CONCLUSION The primary mechanism of Ho : YAG lithotripsy is photothermal . There are no significant photoacoustic effects BACKGROUND To establish the best treatment modality in our hospitals for patients with proximal-ureteral calculi 5 to 10 mm , we compared the treatment outcome in those who underwent  primary ureteroscopy ( URS )  with that in patients who underwent primary in-situ SWL . The primary endpoints were stone-free rates at 3 weeks and 3 months and the subjective patient experience . PATIENTS AND METHODS The study was a prospect i ve patient-preference trial . From September 2002 to May 2005 , 80 patients were included , of whom 71 could be evaluated . Thirty-three patients were treated with SWL and 38 with semirigid or flexible URS .  Stone status was evaluated with excretory urography or noncontrast helical CT . The bother score of urinary-tract symptoms was recorded on a visual analog scale . RESULTS The stone-free rate at 3 weeks was 58 % and 78 % ( P = 0.061 ) and at 3 months 88 % and 89 % ( P = 1 ) for SWL and URS , respectively . The percentage of patients in need of analgesics was 30 % and 49 % ( P = 0.118 ) at 3 weeks and 9 % and 21 % ( P = 0.181 ) at 3 months for the SWL and the URS group , respectively . The bother score regarding dysuria , hematuria , and flank pain were statistically significant in favor of SWL . CONCLUSION Ureteroscopy tends to make patients stone free faster , but SWL is preferred by most patients because there is less discomfort after treatment We performed a prospect i ve , non-r and omised study to determine the appropriate first-line treatment modality for distal ureteral stones . Between 2003 and 2004 , a total of 124 patients with distal ureteral calculi were entered into the study ( mean age 48 years , 35 women and 99 men ) . Sixty-two patients were treated with shock wave lithotripsy ( SWL ) and 62 patients with ureteroscopy ( URS ) .  The average stone size was 6.9 mm ( 3–33 mm ) for SWL and 7.2 mm ( 3–30 mm ) for URS . The treatment decision depended on the patients ’ preference and clinical parameters ( i.e. contraindications for anaesthesia ) . URS was performed under general anaesthesia , using semirigid 8 Fr instruments . SWL was performed under analgo-sedation using a Modulith SLX . Of patients treated with SWL , 84 % had a treatment success within 7 days , 98 % after URS . These results show a significant success ( P=0.005 ) in favour of URS . The average in-patient stay after SWL  was 3 days and for URS 4 days ( not significant ) . The results show a high efficacy and a low complication rate for both modalities . The attained stone-free rate shows a significant advantage for primary URS INTRODUCTION The aim of this study was to investigate and compare the success and complication rates of extracorporeal shockwave lithotripsy ( SWL ) in three cohorts of patients older than 60 years . PATIENTS AND METHODS Our study included 444 patients older than 60 years who were treated with SWL between May 2001 and May 2008 at the Croatian Referential Center for Urolythiasis in Osijek . Three groups were formed : group 
    Output:
    
EVIDENCE SYNTHESIS For stones that do not pass spontaneously or with MET ,  shock wave lithotripsy ( SWL ) and ureteroscopy ( URS ) are the most common and efficient treatment modalities .
Both techniques have obvious advantages and disadvantages as well as different patterns of complications .
For select cases or patients , other modalities may be useful .
Ureteral stones of up to 10 mm and eligible for observation may be offered MET .