***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: Objectives : To compare the success and complication rates of sonography-guided supine percutaneous nephrolithotomy ( PCNL ) versus prone st and ard technique ( fluoroscopic guidance ) in a r and omized controlled trial . Subjects and Methods : Between April 2009 and August 2011 , 92 c and i date s for PCNL  were r and omly divided into two groups : 46 B-mode sonography-guided supine PCNL ( group A ) and 46 st and ard fluoroscopic-guided prone PCNL ( group B ) . Demographic , clinical and perioperative patient characteristics were analyzed , and complications and success rates were compared between the two approaches . Results : Preoperative parameters were comparable in the two groups . The primary success rate was 79.0 and 65.2 % in groups A and B , respectively , after one session of PCNL ( p = 0.485 ) . Sonography-guided access failed in 3 cases ( failure rate 6.5 % in group A vs. 0 % in group B ) . Mean hospital stay ( 2.48 days for group A vs. 2.95 days for group B ; p = 0.039 ) and mean nephrostomy tube stay time ( 1.79 days for group A vs. 2.56 days for group B ; p = 0.007 ) were significantly prolonged in the st and ard technique . Postoperative fever was more prevalent in the st and ard PCNL group ( p = 0.024 ) , but no significant difference was observed in other complications between the two groups . Conclusion : In this study , sonography-guided supine PCNL was presented as a safe and effective technique , similar to st and ard PCNL , with comparable success and complication rates . In addition , using this technique eliminates the possible harmful impacts of radiation on the surgical team and decreases postoperative fever BACKGROUND Middle calyx access has been underused in percutaneous nephrolithotomy  ( PCNL ) , especially in the supine position . We compared the safety and efficacy outcomes between middle calyx and lower calyx accesses in the complete supine PCNL in a non-r and omized single-surgeon clinical study . METHODS Between February 2008 and October 2011 , 170 patients underwent posterior subcostal single tract complete supine PCNL with one-shot dilation and middle calyx ( n = 48 ) and lower calyx ( n = 122 ) accesses . Stone location and surgeon decision determined target calyx for access . Inclusion criteria were pelvis stones , staghorn stones and multiple location stones . Exclusion criteria were renal anomalies , only upper calyx stones , only middle calyx stones and only lower calyx stones . Important parameters were compared between the two groups . A p value of < 0.05 was considered significant . RESULTS Two groups were similar in important patient- and stone-related parameters . Mean operative time ( 60.7 minutes ) , mean postoperative hospital stay ( 1.84 days ) and mean hemoglobin drop ( 0.67 g/dL ) in the middle calyx group were significantly lesser than in the lower calyx group ( 80.1 minutes , 2.19 days , 1.36 g/dL ) . The middle calyx group ( 89.6 % ; 79.6 % ) had a higher stone-free rate ( p = 0.054 ) and efficiency quotient than the lower calyx group ( 76.2 % ; 61.6 % ) . In the middle calyx group ( 10.4 % ; 2.1 % ) , complication and transfusion rates were lesser ( p > 0.05 ) than lower calyx group ( 14.8 % ; 7.4 % ) . No significant difference ( p = 0.40 ) was seen between two groups using the modified Clavien classification of complications . INTERPRETATION Middle calyx can be an optimal access in PCNL with the complete supine position for many of upper urinary tract stones due to its superior outcomes Objective : To compare operative time , safety and effectiveness of minimally invasive percutaneous nephrolithotomy ( MPCNL ) in the supine lithotomy versus prone position . Methods : Between January 2008 and December 2010 , a total of 109 consecutive patients with upper urinary tract calculi were enrolled and r and omly divided into group A ( 53 patients , supine lithotomy position ) and group B ( 56 patients , prone position ) . The MPCNL procedures were performed under the guidance of real-time grayscale ultrasound system . The preoperative characteristics , intraoperative and postoperative parameters were analyzed and compared . Results : All patients were successfully operated . There was no signiﬁcant difference between the two groups in stone-free rate ( group A 90.1 vs. group B 87.5 % , p = 0.45 ) , mean blood loss , number of access tracts , calyx puncture , mean hospital stay ( group A 6 ± 1.1 vs. group B 6 ± 1.5 days , p = 0.38 ) and complications . But the operative time was significantly shortened in supine lithotomy position ( group A 56 ± 15 vs. group B 86 ± 23 min , p < 0.001 ) . Conclusions : The effectiveness and safety of the supine lithotomy position for MPCNL were similar to the prone position . However , the supine lithotomy position has an important advantage of reducing the operative time . The supine lithotomy position could be a good choice to perform MPCNL BACKGROUND AND PURPOSE Gaining access to the pyelocaliceal system in  percutaneous nephrolithotomy ( PCNL )  is routinely performed using fluoroscopic guidance with the patient in a prone position . We compared ultrasonography-guided access for PCNL with the patient in the flank position with conventional fluoroscopy-guided access . PATIENTS AND METHODS A total of 60 patients were r and omly separated into two 30-patient groups -- namely , ultrasonography-guided access with the patient in the flank position as group 1 , and fluoroscopy-guided access with the patient in the prone position as group 2 . In group 1 , the entire procedure was performed under ultrasonography guidance . RESULTS Successful access was achieved 100 % in both groups . The success rate was 86.7 % in group 1 and 90 % in group 2 ( P = 0.45 ) . The residual stone rate ( stone > or=4 mm ) was 13.3 % in group 1 and 10 % in group 2 . The access duration was 14.5 + /- 2.6 minutes and 9.4 + /- 2.3 minutes in groups 1 and 2 , respectively ( P < 0.05 ) . No significant differences for complications without any adjacent injuries were detected in both groups . Furthermore , the average hospital stay was 2.7 + /- 0.3 and 2.9 + /- 0.3 days accordingly for groups 1 and 2 ( P = 0.89 ) . CONCLUSION Ultrasonography has a high ability to access calculi more easily through the pyelocaliceal system with the patient in the flank position . It is convenient for urologists , and the return to the supine position is possible easily when necessary . Besides , PCNL under ultrasonography guidance and with the patient in the flank position has high success rates and limited complications ; hence , we recommend this technique as an alternative procedure for fluoroscopy-guided PCNL Objective : To perform a prospect i ve r and omized trial comparing the efficacy and safety of percutaneous nephrolithotomy ( PCNL ) in the prone and modified supine positions . Methods : Between August 2010 and August 2011 , 102 patients with renal calculi and 20 patients with ureteral calculi were r and omized to undergo fluoroscopy and ultrasound-guided PCNL procedures in the prone or modified supine position .  Baseline characteristics , puncture position , numbers of punctures , operation time , stone free rate , loss of blood , hospital stay and second phase PCNL were compared in the two groups . Results : There were no significant differences in gender , age , body mass index , stone location , stone size and the presence of hydronephrosis between the two groups . The rate of second PCNL was significantly higher and the stone clearance rate was significantly lower in the modified supine than in the prone position group . Mean operation time was significantly lower in the prone than in the modified supine position group ( 78 min vs 88 min , P<0.05 ) . There were no significant differences in rates of rib and calyx puncture , numbers of punctures , mean blood loss , and mean hospital stay between the two groups . Conclusions : Both the prone and modified supine positions are effective and safe for PCNL . Operation time was longer in the modified supine group , and patients undergoing PCNL in the modified supine position more frequently required a second operation due to a lower stone clearance rate OBJECTIVES To compare operative time , safety , and effectiveness of percutaneous nephrolithotomy  in the supine versus prone position in a prospect i ve r and omized trial . MATERIAL AND METHODS From October 2005 to June 2007 , 75 patients ( 33 men , 42 women ; mean age , 39.3 yr ) were prospect ively enrolled and r and omly divided into group A ( 39 patients ,  supine position ) and group B ( 36 patients , prone position ) . Inclusion criteria were diagnosis of single or multiple renal stones ( pelvic-caliceal ) treatable with a single percutaneous access , stone diameter > 2.5 cm , body mass index ( BMI ) < 30kg/m(2 ) , and no contraindications to perform the operation in the prone position . Exclusion criteria were stones in more than one calyx , complete staghorn stones , and coexisting renal anomalies . RESULTS The two groups were comparable in age , BMI , male-to-female ratio , and stone size . No significant difference was ascertained between the two groups in terms of stone-free rate ( group A , 88.7 % vs. group B , 91.6 % , p=0.12 ) , mean blood loss ( group A , Delta hemoglobin -2.3g/dl vs. group B , -2.2g/dl , p=0.23 ) , and mean hospital stay ( group A , 4.3 d vs. group B , 4.1 d , p=0.18 ) . The only significant difference reported was mean operative time ( group A , 43min vs. group B , 68min , p<0.001 ) . No blood transfusions were needed and no organ injuries were reported . CONCLUSIONS In this carefully selected patient population with uncomplicated renal stones , the supine position was similar to the prone position for percutaneous stone removal PURPOSE To determine differences in patients ' characteristics , operative time and procedures , and perioperative outcomes between prone and supine positioning in percutaneous nephrolithotomy ( PCNL )  using the Clinical Research Office of the Endourological Society ( CROES ) PCNL Global Study data base . PATIENTS AND METHODS Between November 2007 and December 2009 , prospect i ve data were collected on a total of 5803 consecutive patients who were treated over a 1-year period at each of 96 participating global centers . Patients with data on body position were dichotomized into prone or supine PCNL . RESULTS The majority of PCNL treatments were performed in the prone position ( n=4637 ; 80.3 % of sample ) . Differences in patient characteristics included in the prone group : A greater proportion of males ( 57.4 % vs 52.2 % ) ; younger age ( 48.8 y vs 51.0 y ) ; less frequent history of shockwave lithotripsy ( 19.5 % vs 28.6 % ) ; greater frequency of American Society of Anesthesiologists score of 1 ( 54.7 % vs 46.8 % ) ; and a Clavien grade of 2 or more ( 10.0 % vs 7.2 % ) . The mean operative time was significantly lower for prone vs supine PCNL ( 82.7 min vs 90.1 min ) regardless of the method of tract dilation , while the stone-free rate was significantly higher ( 77.0 % vs 70.2 % ) . Compared with supine patients , prone patients exhibited higher rates of blood transfusions ( 6.1 % vs 4.3 % ) and fever ( 11.1 % vs 7.6 % ) , but lower rates of failed procedures ( 1.5 % vs 2.7 % ) . CONCLUSIONS Since operative time and stone-free rates favor prone PCNL , but patient safety favors supine PCNL , the choice of patient position should be tailored to individual patient characteristics and the surgeon 's preference OBJECTIVE The gold st and ard for removal of renal stones more than 2 cm in diameter is  percutaneous nephrolithotripsy ( PCNL ) . Retro grade intrarenal surgery ( RIRS ) has become more and more fashionable because of its high safety and repeatability , especially in smaller stones . Many retrospective studies have proved its efficacy and safety in larger calculi , however . We decided to compare prospect ively both procedures in terms of safety and efficacy in renal pelvic stones more than 2 cm in diameter . PATIENTS AND METHODS This was a r and omized single tertiary care center trial with two arms ( 32 patients in each arm ) . The first group comprised patients who underwent PCNL , while in the second group , there were patients in whom RIRS with a semirigid ureteroscope was used . The primary end points were hematocrit and hemoglobin drop after surgery as equivalents of safety and stone disintegration rate in terms of efficacy . The secondary end points comprised operating room time , visual analogue scale of pain , pain treatment , and hospital stay . RES 
    Output:
    
CONCLUSION Supine PCNL has similar stone-free rate , operation time , and hospital stay relative to prone PCNL .
However , the supine position has the advantage of less fever and need for blood transfusion .
Although both prone and supine PCNLs are suggested for treatment , supine PCNL may have advantages especially in patients with comorbidity .