***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: The aim of this study was to introduce a novel male contraceptive method , an intra-vas device ( IVD ) , and to assess the efficacy , safety and satisfaction of recipients compared with no-scalpel vasectomy ( NSV ) . A phase II r and omized controlled trial was conducted in China in 2003 . Two hundred and eighty-eight male subjects seeking vasectomy were r and omly assigned to the IVD or NSV group . Follow up included a telephone question naire on the 14th postoperative day and visits at the third and 12th postoperative months . The follow-up rates at the three time points were 100 % , 100 % and 96.5 % respectively . There was no technical failure in any subject . The surgical conditions were similar in both groups , but the IVD group experienced an additional 5 min of operative time ( p<0.001 ) . The IVD group recovered normal activity and sexual intercourse more rapidly ( both p<0.05 ) . The azoospermia rate was lower in the IVD group than in the NSV group at the third and 12th postoperative months . The rate of contraceptive success based on semen analyses was similar in both groups , especially at the 12th postoperative month ( 94.3 % in the IVD group vs. 98.6 % in the NSV group ; p=0.054 ) . The IVD group had less risk of complications ( i.e. pain , congestive epididymitis and sperm granuloma ) . More subjects reported satisfaction with IVD sterilization than with NSV . The two procedures were similar in terms of surgical complications . The IVD was slightly less effective , but had a lower risk of later adverse events than the NSV technique . The IVD group also reported a higher level of satisfaction Proper r and omisation means little if investigators can not include all r and omised participants in the primary analysis . Participants might ignore follow-up , leave town , or take aspartame when instructed to take aspirin . Exclusions before r and omisation do not bias the treatment comparison , but they can hurt generalisability . Eligibility criteria for a trial should be clear , specific , and applied before r and omisation . Readers should assess whether any of the criteria make the trial sample atypical or unrepresentative of the people in which they are interested . In principle , assessment of exclusions after r and omisation is simple : none are allowed . For the primary analysis , all participants enrolled should be included and analysed as part of the original group assigned ( an intent-to-treat analysis ) . In reality , however , losses frequently occur . Investigators should , therefore , commit adequate re sources to develop and implement procedures to maximise retention of participants . Moreover , research ers should provide clear , explicit information on the progress of all r and omised participants through the trial by use of , for instance , a trial profile . Investigators can also do secondary analyses on , for instance , per- protocol or as-treated participants . Such analyses should be described as secondary and non-r and omised comparisons . Mish and ling of exclusions causes serious method ological difficulties . Unfortunately , some explanations for mish and ling exclusions intuitively appeal to readers , disguising the seriousness of the issues . Creative mismanagement of exclusions can undermine trial validity In 59 consecutive vasectomies for the purpose of sterilization , one-half , chosen by r and om numbers , received an irrigation of the vas deferens with 40 ml of sterile water on each side . Afterwards , the men sent in every fourth ejaculation , until two consecutive sample s were without spermatozoa . The postoperative sperm sample s were examined microscopically without knowing whether the man belonged to the treated group or the control group . The irrigation procedure did not shorten the time needed to reach azoospermia Background R and omized controlled trials comparing different vasectomy occlusion techniques are lacking . Thus , this multicenter r and omized trial was conducted to compare the probability of the success of ligation and excision vasectomy with , versus without , fascial interposition ( i.e. placing a layer of the vas sheath between two cut ends of the vas ) . Methods The trial was conducted between December 1999 and June 2002 with a single planned interim analysis . Men requesting vasectomies at eight outpatient clinics in seven countries in North America , Latin America , and Asia were included in the study . The men were r and omized to receive vasectomy with versus without fascial interposition . All surgeons performed the vasectomies using the no-scalpel approach to the vas . Participants had a semen analysis two weeks after vasectomy and then every four weeks up to 34 weeks . The primary outcome measure was time to azoospermia . Additional outcome measures were time to severe oligozoospermia ( < 100 000 sperm/mL ) and vasectomy failure based on semen analyses . Results We halted recruitment after the planned interim analysis , when 841 men had been enrolled .  Fascial interposition decreased time to azoospermia ( hazard ratio [ HR ] , 1.35 ; P < 0.0001 ) and time to severe oligozoospermia ( HR , 1.32 ; P < 0.0001 ) and reduced failures based on semen analysis by about half , from 12.7 % ( 95 % confidence interval [ CI ] , 9.7 to 16.3 ) to 5.9 % ( 95 % CI , 3.8 to 8.6 ) ( P < 0.0001 ) . Older men benefited less from fascial interposition than younger men in terms of the speed of achieving azoospermia . However , the number of vasectomy failures was reduced to a similar degree in all age groups . Slightly more adverse events occurred in the fascial interposition group , but the difference was not significant . These failure rates may appear high to practitioners in countries such as the USA , but they are similar to results from other careful studies of ligation and excision techniques . Conclusion Fascial interposition significantly improves vasectomy success when ligation and excision is the method of vas occlusion . A limitation of this study is that the correlation between postvasectomy sperm concentrations and risk of pregnancy is not well quantified This paper describes two consecutive studies : a volume study and an efficacy study . The volume study determined the appropriated volume of Medical Grade Silicone Rubber ( MSR ) needed to achieve complete occlusion of the vas deferens . This was done by in-vitro testing of 130 human vas specimens containing plugs of MSR formed in vivo . The volume of MSR needed to occlude the vas was 0.1531 + /- 0.0059 ml injected by five to six turns of the applicator h and wheel . There was a correlation between  MSR volume , weight , and the number of turns of the applicator h and wheel . An influence of body height upon the volume and weight of the MSR  was also observed . An oval shaped clamp ( 15 mm long ) was more effective in producing secure vas occlusion than was a round clamp ( 10 mm long ) . The mean outer diameter of the vas specimens was 1.80 + /0 0.15 mm , and the mean maximum dilated inner diameter was 0.93 + /- 0.11 mm . The efficacy study was a clinical trial to compare MSR  was occlusion ( using an oval 15 mm clamp and the appropriate volume derived from the volume study , n = 58 ) with no-scalpel vasectomy as the st and ard procedure ( n = 64 ) . The azoospermia rate following MSR vas occlusion was not significantly different from that following no-scalpel vasectomy , and was achieved in 3 - 6 months Family Health International ( FHI ) and EngenderHealth conducted a multicenter , r and omized controlled trial to evaluate a fascial interposition ( FI ) component of a vas occlusion procedure for male sterilization . A data monitoring committee ( DMC ) was established to provide independent review of the interim report . The DMC met to review the interim report after enrollment of 552 men . As planned , an estimate of the hazard ratio ( HR ) for successful vasectomy for the FI group versus the no-FI group controlling for age of the participant and level of experience of the surgeon was obtained for the interim report using Cox 's proportional hazards regression . The main analysis comparing time to vasectomy success , defined as two consecutive azoospermic semen sample s , was highly significant and met the prespecified level for stopping enrollment ( HR=1.54 , p<0.01 ) . However , a troublesome age by vasectomy technique interaction became apparent in the analysis . FI was clearly beneficial for younger males . However , the trend for older men was not as clear . The DMC recommended continuing the trial to better study this interaction and obtain more data to clarify the effect of FI for older men . After consulting further with the DMC , the study statisticians presented the interim report to senior management at FHI . A meeting between FHI senior management and the DMC followed . After much deliberation , trial enrollment was terminated . Follow-up of participants already enrolled in the study continued as planned . This paper presents the issues involved in the decision to terminate the study OBJECTIVES To assess the effect of irrigation of the distal vas deferens with sterile water at the time of vasectomy on sperm clearance . Is it possible to accelerate clearance and avoid the problem of lingering sperm ? METHODS Two hundred men undergoing vasectomy were r and omized to receive either a st and ard vasectomy or vasectomy plus irrigation of each vas deferens with sterile water . The interval between vasectomy and the production of two azoospermic semen sample s was recorded . RESULTS Overall , 37 patients were excluded for failing to follow the postvasectomy protocol for semen analysis , leaving 87 in the control group and 76 who received vasal irrigation . No statistically significant differences existed between the two groups with regard to the mean time to clearance ( 26.4 weeks , control group versus 28.6 weeks , flush group ) , proportion clear at 16 weeks ( 29 % versus 21 % ) , or proportion with lingering sperm at 40 weeks ( 22 % versus 26 % ) . CONCLUSIONS Irrigation of the vas deferens with sterile water does not accelerate the clearance of spermatozoa after vasectomy . Men wishing to undergo vasectomy must be counseled about the possibility of lingering sperm Objective To determine the effect of perioperative distal vasal lavage with 50 mL of normal saline on subsequent time to azoospermia after vasectomy No-scalpel vasectomy was developed to increase acceptability of vasectomy by elimination of the fear of the incision . Although this method has been used for over 8,000,000 men , the technique is largely unknown in developed countries . During the King 's birthday vasectomy festival no-scalpel vasectomy was compared with st and ard incisional vasectomy in 1203 patients . An average of 57 procedures per day could be done by each physician with the no-scalpel method , compared to 33 procedures with the st and ard method ( p less than 0.001 ) . The complication rate was 0.4/100 procedures for no-scalpel vasectomy compared with 3.1/100 for st and ard vasectomy ( p less than 0.001 ) . No-scalpel vasectomy is a rapid and economic alternative to st and ard vasectomy , with fewer complications and increased patient acceptability OBJECTIVE To assess the impact of intraoperative distal vasal flushing during no-scalpel vasectomy on hastening the sperm clearance from the vas deferens and subsequent postvasectomy time to azoospermia . MATERIAL AND METHODS A total of 906 men undergoing vasectomy at our center from October 2007 to August 2008 were included in this prospect i ve , r and omized , controlled study . Patients were alternately allocated to 1 of 2 groups . Group A were patients who underwent no scalpel vasectomy alone ; Group B patients , in addition to no scalpel vasectomy , underwent flushing of the distal vasal segment with 30 mL of sterile water .  Postvasectomy semen analysis was done at 4 , 8 , and 12 weeks . The age , operative time , number of ejaculations , and proportion of patients ' azoospermic at 4 , 8 , and 12 weeks after vasectomy were compared between the 2 groups . RESULTS A total of 727 men were available for final analysis . A significantly higher proportion of patients in group B were azoospermic at 4 and 8 weeks when compared with group A ( group B : 53.40 % and 80.68 % ; group A : 33.86 % and 49.6 % at 4 and 8 weeks , respectively ) . There was no statistically significant difference in the mean age , operative time , and number of ejaculations between the 2 groups . CONCLUSIONS Distal vasal flushing with 30 mL of sterile water may shorten the time to azoospermia for between 20 % and 30 % of vasectomy patients . Thus , this procedure may be an option for some who choose the vasal flush to avoid the long duration of postvasectomy alternate contraceptive methods CONTEXT Vasectomy is a common method of contraception , but concern exists about a reported association with risk of prostate cancer . OBJECTIVE To examine whether vasectomy increases risk of prostate cancer . DESIGN , SETTING , AND PARTICIPANTS National population -based case-control study of 923 new cases of prostate cancer among men aged 40 to 74 years from the New Zeal and Cancer Registry who were on the general electoral roll . Controls ( n = 1224 ) were r and omly selected from the general electoral roll , with frequency matching to cases in 5-year age groups . Cases ( 3 - 15 months after diagnosis ) and controls were interviewed by telephone between January 1997 and November 1999 . MAIN OUTCOME MEASURES Relative risk ( RR ) of prostate cancer for men who had had a vasectomy vs those who had not . RESULTS There was no association between prostate cancer and vasectomy  ( RR ,  
    Output:
    
Fascial interposition had more surgical difficulties , but the groups were similar in side effects .
Fascial interposition reduced vasectomy failure .
An intra-vas device was less effective in reducing sperm count than was no-scalpel vasectomy .