the introduction of laparoscopic procedures has revolutionized surgery , paving the way for minimally invasive procedures . to improve safety , outcomes , and cosmesis , and to further reduce invasiveness , after raman et al performed the first urologic less , this technique has been used for various urologic diseases [ 2 - 7 ] and has gradually been extended to pediatric cases [ 8 - 10 ] . researchers have reported the feasibility and short - term outcomes of less with their own modifications ; however , to our knowledge , there have been no reports on the large - scale use of less procedures in asia [ 2 - 4,11 ] . therefore , we present 171 consecutive cases of urologic less , including robotic procedures , in which our homemade port device was used . from december 2008 to august 2010 , 171 cases of less were performed in our institution . conventional less ( c - less ) and robotic less ( r - less ) were performed by three expert laparoscopic surgeons . the disease - specific inclusion and exclusion criteria for less were the same as for conventional laparoscopic surgery . patients were given a choice of conventional laparoscopy , c - less , r - less , or open surgery . we described the expected surgical and postoperative outcomes , including pain and incisional wounds , with our own data and photographs . we also explained the advantages and disadvantages of less and its cost compared with other surgery types . cancer patients were evaluated by computed tomography ( ct ) or positron emission tomography - ct ( pet - ct ) at 3 , 6 , and 12 months after surgery , and then every 6 months if there was no evidence of recurrence or metastasis . the present study was approved by the institutional review board at yonsei severance hospital , seoul , korea . through the 2 to 5 cm umbilical incision , we placed the port device with a size 7 powder - free surgical glove and wound retractor for both c - less and r - less . for c - less , a total of three or four trocars ( 12 mm and 5 mm ) were used ( fig . a 10 mm 30 rigid laparoscope ( stryker , kalamazoo , mi , usa ) with integrated camera and right - angled light cable adaptor was used . in some cases , an additional 5 mm or 2 mm trocar was used for liver retraction or pelvic surgery . we used conventional laparoscopic instruments and flexible articulating laparoscopic instruments depending on the type of procedure . articulating devices such as hook cautery and scissors were used with the dominant hand only for renal vascular dissection , upper posterior kidney dissection , and adrenal dissection . the homemade single - port system was placed for r - less ( da vinci s , intuitive surgical , sunnyvale , usa ) as it was for c - less . the camera was inserted through the 12 mm trocar and the robot arms were inserted thorough the 8 mm port . in most cases , an additional trocar was inserted alongside the port device to create a 12 mm hybrid port . to prevent the outer clashing of robotic arms , the scope was placed at a 30 upward angle to the robotic arms ( fig . we maintained intra - abdominal pressure under 12 mmhg and checked the glove to ensure that it did not inflate . between 2008 and 2010 , 171 patients underwent c - less ( n=98 ) or r - less ( n=73 ) for various urologic diseases ( male , n=94 [ 55% ] ; female , n=77 [ 45% ] ) . mean patient age was 53 years ( range , 1 - 86 years ) , and mean body mass index was 23.7 kg / m ( range , 14.3 - 32.9 kg / m ) . thirty - three patients ( 19.3% ) had undergone previous abdominal surgery , and seven cases were converted to mini - incision open surgery owing to severe adhesions from previous surgery ( c - less , n=3 ; r - less n=2 ) , failure to identify endophytic renal mass even by intraoperative ultrasonogram ( r - less n=1 ) , or inferior vena cava injury ( c - less n=1 ) . mean operative time was 190.8 min ( range , 20 - 440 min ) , and mean ischemic time for partial nephrectomy was 26 min ( range , 11 - 65 min ) . mean estimated blood loss ( ebl ) was 204 ml ( range , < 10 - 2,700 ml ) , and the total transfusion rate was 9% . the mean hospital stay was 4.5 days ( range , 1 - 19 days ) . intraoperative complications occurred in seven cases ( 4.1% ) : diaphragm injury during c - less radical nephrectomy ( n=2 ) , bowel injury during c - less partial nephrectomy and r - less simple nephrectomy ( n=2 ) , inferior vena cava injury during c - less simple nephrectomy ( n=1 ) , renal vein injury ( n=1 ) , and ureter injury during r - less partial nephrectomy ( n=1 ) . an additional port was used for seven right renal surgeries and one pelvic surgery during c - less ( 4.7% ) . most r - less procedures used an additional hybrid port except for simple and radical nephrectomies . wound dehiscence ( clavien - dindo grade i ) occurred in three patients ; however , they did not require secondary closure . one patient suffered from prolonged ileus after c - less ( grade i ) , but recovered and was discharged according to schedule . acute renal failure ( grade i ) developed immediately after r - less nephroureterectomy , but patients recovered with hydration and diuretics . after c - less nephroureterectomy , one patient developed a retroperitoneal abscess on postoperative day 8 and was treated with antibiotics ( grade ii ) . one retroperitoneal abscess ( grade iiia ) was detected on postoperative day 11 after r - less nephroureterectomy and was treated with antibiotics and pigtail drainage for 8 days . in one c - less pyeloplasty , the ureteral catheter migrated downward on postoperative day 4 ( grade iiia ) ; the patient reported flank pain , so we exchanged the ureteral catheter . two cases with focal positive margins underwent r - less partial nephrectomy . in these cases , intraoperative analysis of frozen sections was negative , and no evidence of recurrence was found at the 1-month or 6-month follow - up ct evaluations of either patient . one patient who underwent c - less radical nephrectomy eventually received a diagnosis of ewing sarcoma ; multiple lymph node metastasis and bone metastasis were detected within 2 months . other than this case , no recurrence or metastasis was reported during follow - up ( mean follow - up , 9.4 months ) . even leiomyosarcoma , which was treated by c - less adrenalectomy , had not recurred by the 15-month follow - up . perioperative outcomes and specific comments regarding each type of surgery are shown in table 1 . in recent decades , laparoscopic surgery has undergone rapid technical development and advances in laparoscopic instruments . the aims of laparoscopic surgery include minimal invasiveness , safety , and cost - effectiveness ; thus , laparoscopic surgeons have worked to continuously improve the surgical techniques . the last 3 years have witnessed a rapid expansion of less for various urologic diseases . to evaluate less , worldwide experiences have been reported , including large - scale studies conducted in a single institution . table 1 compares the outcomes of previous studies with our data [ 2,15 - 22 ] . desai et al performed a total of 100 less procedures including simple prostatectomy ( 32% ) , donor nephrectomy ( 17% ) , pyeloplasty ( 17% ) , simple nephrectomy ( 14% ) , and partial nephrectomy ( 6% ) . white et al reported the same number of less procedures including donor nephrectomy ( 19% ) , partial nephrectomy ( 15% ) , sacral colpopexy ( 13% ) , and renal cryotherapy ( 8% ) . indications for less in the present study differed somewhat from those of the previous studies . in our study , more than half of the less procedures were performed for malignancies , 59 ( 34.5% ) of the less cases were performed for partial nephrectomy , and 26 ( 15.2% ) for radical nephrectomy . however , this difference may be due to different patient populations rather than the surgeons ' preferences . the ideal indications for less may be pediatric urologic diseases and benign diseases for which cosmetic outcomes are important . park et al and marietti et al have reported outcomes for c - less in simple nephrectomies for pediatric cases of nonfunctioning kidney . in the present study , four pediatric patients underwent c - less : two nephroureterectomies for nonfunctioning kidney , one partial nephrectomy for metanephric adenoma , and one ureterectomy for ectopic ureter were successfully performed without complications . similarly , surgeries that require smaller incisions for specimen extraction appear to be good indications for less . patients are more concerned with cosmesis in non - life - threatening diseases such as ureteropelvic junction obstruction , renal cyst , or ureteral stone . in addition , these surgical procedures do not require a wide surgical field , and the specimens are smaller than the single - port device . we have expanded the use of less to pyeloplasty , ureterolithotomy , and other benign surgeries such as urachal mass excision , orchiectomy , seminal vesiculotomy , and retroperitoneal mass excision , as shown in table 1 . comparing the indications for c - less and r - less , r - less was more suitable for technically demanding procedures requiring meticulous intracorporeal suturing such as partial nephrectomy and bladder cuff resection . on the other hand , c - less is relatively suitable for simple and radical nephrectomy , renal cyst decortications , ureterolithotomy , and pediatric surgery because these can be comfortably performed without the expensive robot assistance even with standard laparoscopic instruments . for partial nephrectomy , we preferred to use r - less ( 94% ) , because the robotic endowrist and hybrid port technique was more convenient and safe for upper posterior renal dissection and hilar management . with this system , we could also perform the meticulous suturing for renorrhaphy without difficulty . in the first c - less nephroureterectomy even with stay sutures , deep bladder cuff resection using the laparoscopic endoshears ( including detrusor muscle as previously reported ) was somewhat difficult in c - less . in contrast , robotic assistance could make a deep bladder cuff resection and convenient suturing of the bladder defect . however , lymph node dissection was not performed in all nephroureterectomy cases , because only low - grade tumors were selected . the operative outcomes of the present study were comparable to those of previous studies ( table 1 ) . however , in partial nephrectomy , the mean ebl of our c - less procedures ( 70 ml ) was noticeably less than that of other studies ( 150 - 475 ml ) . in contrast , the mean ebl of r - less procedures ( 273 ml ) was greater than that reported by a previous study ( 100 ml ) , but was still smaller than that of c - less procedures in other studies . these differences may not be due to differences in technical skill , but may be the result of different surgical indications . when we began treating partial nephrectomies with c - less , we limited the procedure to exophytic anterior lower pole masses . after the transition to r - less , we gradually expanded the indication to endophytic and upper posterior masses , because r - less enables more accurate suturing and safer hilar and upper pole management . the mean ebl for c - less simple nephrectomy was larger than that reported in other studies , and larger than that of radical nephrectomy and even partial nephrectomy in our study , because of three cases : the surgeon 's first less case , inferior vena cava injury in one case , and multiple renal vessels in one case . however , desai et al reported 4/100 ( 4% ) intraoperative complications that included gonadal vein avulsion , bowel injury , bleeding requiring sutures , and renal vein injury . in the present study , seven intraoperative complications ( 4.1% ) occurred , and one case ( inferior vena cava injury ) the total conversion rate ( 7/171 [ 4.1% ] ) was lower than that of the two previous studies with 100 cases ( conversion rates , 6% and 7% ) . we were able to successfully manage intraoperative accidents without conversion by effective internal retractions through our homemade port device . this was possible because the glove used for the port device provided a wide range of motion , and various trocar sizes could be used . in addition , the residual finger space in the gloves , which replaced a retrieval bag for sealing the small specimen , provided more room for important procedures . in the present study , most of the intraoperative accidents occurred in our first 30 cases and during partial nephrectomy . this finding suggests that even experienced surgeons experience some difficulty adapting to the single port . in addition , partial nephrectomy , which requires meticulous parenchymal suturing and careful vascular control , is as challenging a technique in less as it has been in conventional laparoscopy and robotic surgery . desai et al reported five cases ( 5% ) of postoperative complications including urinary tract infection ( clavien - dindo grade ii ) ; postoperative bleeding requiring transfusion ( grade ii ) , angioembolization ( grade iiia ) , and exploration ( grade iiib ) ; and one mortality ( grade iv ) . white et al reported 10 cases ( 10% ) of postoperative complications with seven cases of blood transfusion ( grade ii ) , urinary tract infection ( grade ii ) , rectovesical fistula requiring operation ( grade iiib ) , and readmission to the intensive care unit and angioembolization due to postoperative bleeding in partial nephrectomy cases ( grade iva ) . although it is difficult to compare outcomes from different types of surgery , the postoperative complication rate of the present study ( 5.3% ) was similar to or lower than the rates of previous studies , and the complications in the present study were less severe . the duration of follow - up in the present study was not sufficient to evaluate oncologic outcomes ( 9.4 months ) . however , no cancer - related events were observed other than progression of ewing sarcoma in one case . long - term follow - up data must be analyzed and compared with results from conventional laparoscopic surgery and open surgery . less is an attractive surgical modality that has advanced the ultimate aim of minimally invasive surgery ; however , aspects of less can be improved . first , a suturing technique is needed that allows meticulous suturing of renal parenchyma and various anastomoses . the conventional triangular arrangement of instruments is not used in less ; therefore , some conventional laparoscopic suture techniques can not be performed . second , because less is increasing continuously , standard indications are needed for each less procedure . less is still a challenging technique ; accordingly , leading laparoscopic surgeons should be responsible for establishing indications . for this reason , instrumental clashing was unavoidable , and we used a hybrid port technique . with these changes , we did not attempt to evaluate the superiority of less over conventional laparoscopy or robotic surgery . in addition , cosmetic outcomes and quality of life data were not evaluated . to overcome these limitations , additional surgical experience , longer we presented 171 cases of urologic less procedures performed with the use of a homemade single - port device . we have demonstrated that less is feasible and can be safely applied to a variety of urologic operations , although less is still a challenging technique for urologic conditions . long - term follow - up will be needed to prove the safety , cosmesis , and cost - effectiveness of less and provide a comparative analysis with other procedures to confirm the significant benefits of less .
purposewe report our experience to date with 171 patients who underwent laparoendoscopic single - site surgery for diverse urologic diseases in a single institution.materials and methodsbetween december 2008 and august 2010 , we performed 171 consecutive laparoendoscopic single - site surgeries . 
 these included simple nephrectomy ( n=18 ; robotic surgeries , n=1 ) , radical nephrectomy ( n=26 ; robotic surgeries , n=2 ) , partial nephrectomy ( n=59 ; robotic surgeries , n=56 ) , nephroureterectomy ( n=20 ; robotic surgeries , n=12 ) , pyeloplasty ( n=4 ) , renal cyst decortications ( n=22 ) , adrenalectomy ( n=4 ; robotic surgeries , n=2 ) , ureterolithotomy ( n=10 ) , partial cystectomy ( n=3 ) , ureterectomy ( n=1 ) , urachal mass excision ( n=1 ) , orchiectomy ( n=1 ) , seminal vesiculectomy ( n=1 ) , and retroperitoneal mass excision ( n=1 ) . 
 all procedures were performed by use of a homemade single - port device with a wound retractor and surgical gloves . 
 a prospective study was performed to evaluate outcomes in 171 cases.resultsof the 171 patients , 98 underwent conventional laparoendoscopic single - site surgery and 73 underwent robotic laparoendoscopic single - site surgery . 
 mean patient age was 53 years , mean operative time was 190.8 minutes , and mean estimated blood loss was 204 ml . 
 intraoperative complications occurred in seven cases ( 4.1% ) , and postoperative complications in nine cases ( 5.3% ) . 
 there were no complications classified as grade iiib or higher ( clavien - dindo classification for surgical complications ) . 
 conversion to mini - incision open surgery occurred in seven ( 4.1% ) cases . 
 regarding oncologic outcomes , no cancer - related events occurred during follow - up other than one aggressive progression of ewing sarcoma.conclusionslaparoendoscopic single - site surgery is technically feasible and safe for various urologic diseases ; however , surgical experience and long - term follow - up are needed to test the superiority of laparoendoscopic single - site surgery .