traditionally , open dismembered pyeloplasty has been the standard treatment for ureteropelvic junction obstruction ( upjo ) . in 1993 ,
schuessler and associates described the first laparoscopic pyeloplasty , and since then it has been shown to result in similar outcomes to open pyeloplasty with a lower morbidity . to decrease the morbidity and improve cosmetic outcomes from conventional laparoscopy
, efforts have been made to develop new techniques with multichannel single - access ports and articulating instruments that allow the laparoscopic procedure to be performed through a single skin incision that is often hidden within the umbilicus , otherwise referred to as laparoendoscopic single - site surgery ( less ) .
less has been used for diverse urological diseases and initial studies have shown that less is safe and feasible in comparison to conventional laparoscopic surgery [ 4 - 8 ] .
in particular , after the report of desai et al on the first less pyeloplasty ( less - p ) , follow - up studies showed similar outcomes with conventional laparoscopic pyeloplasty ( cl - p ) .
however , less is still a technically challenging procedure for beginners because of the difficulty in suturing . here
, we report on our techniques and initial experience with less - p using additional needlescopic instruments and compare the results with cl - p .
we analyzed 9 consecutive patients who underwent less - p between july 2009 and april 2010 .
the clinical data were compared with data from 18 patients out of 31 consecutive patients who underwent cl - p from november 2003 to april 2009 .
the 9 less - p patients were matched 1:2 with the 18 cl - p patients on the basis of age and side of surgery .
the choice of operation was based on the presence of obstruction on the diuretic renogram with either symptoms ( urinary tract infection , recurrent pain , or stone formation ) or functional impairment of the kidney ( relative uptake 40% ) .
all less - p procedures were performed by a single surgeon ( d.h.h . ) , whereas the cl - p procedures were performed by two surgeons ( 17 cases by d.h.h , 1 case by s.s.j . ) in both groups , the operating procedures were performed similarly , except for the number of access points .
a ureteral stent was placed antegradely , except in cases where the stent had been placed before surgery . to perform less - p ,
we used a wound retractor ( alexis ; applied medical , rancho santa margarita , ca , usa ) and a surgical glove as the homemade single - port device as described in our previous series . to make a single port similar to that of a commercial multichannel trocar
we firmly fastened the first , third , and fifth glove finger tips to the end of the three trocars ( two 12 mm trocars and one 5 mm trocar ) with a tie or rubber band .
pneumoperitoneum was made by co2 gas insufflation to 14 mm hg , and a 10 mm rigid laparoscope angled at 30 degrees was inserted .
the operation was performed by using conventional laparoscopic straight working instruments and 5 mm articulating instruments ( autonomy laparo - angle ; cambridge endo , framingham ma , usa ) to overcome the lack of triangulation that occurs with a single port .
we also used additional needlescopic instruments with a 2 mm trocar inserted at the subcostal area to create an environment similar to that for conventional laparoscopic pyeloplasty with ureteropelvic anastomosis ( fig . 1 , 2 ) .
the 2 mm grasper was used to assist with suturing by manipulating the renal pelvis or ureter and adjusting the needle direction ( fig .
the anastomosis was performed by means of a continuously running suture with 4 - 0 polygalactin suture .
a ureteral stent was inserted antegradely through the 2 mm trocar by using a 5 fr .
the 2 mm trocar site did not need to be closed after the operation . in the cl - p group
all patients underwent placement of a jackson - pratt drain through a 5 mm trocar incision in all cl - p cases and through the margin of the umbilical incision in all less - p cases .
prophylactic antibiotics were routinely prescribed . for pain control , we prescribed intravenous ( iv ) patient - controlled analgesia ( pca ) .
infusion of 1,500 g of fentanyl in 100 ml of normal saline was started at a basal infusion rate of 1.0 ml / hr with an iv infusion pump ( automed3200 ; ace medical , seoul , korea ) .
the analgesic bolus of pca ( using a 1.0 ml bolus and a lockout time of 15 minutes in the iv pca group ) was started at the post - anesthesia care unit by the patient after awakening .
additional mso4 was applied when the iv pca was ineffective at reducing or eliminating the pain .
the closed suction drain was subsequently removed if the drainage output did not increase and was less than 100 ml in 24 hours after foley catheter removal .
the perioperative parameters including operative time , intraoperative estimated blood loss , analgesic use , postoperative hospital stay , complications , and success rates were compared between the two groups .
the operative time was recorded from the time of the initial skin incision to the final skin suture . to compare postoperative pain
, we used a numerical rating scale ( nrs ) from 0 ( no pain ) to 10 ( worst possible pain ) , and we looked at the additional mso4 requirement on postoperative day 1 and the discharge day .
the assessment of success was based on improvement in the diuretic renogram , including resolution of clinical symptoms .
all statistical analyses were performed with the spss ver . 17.0 ( spss inc . ,
numerical data from a normal distribution were expressed as a group mean with the standard deviation and were compared by using the student 's t - test .
numerical data from a non - normal distribution were expressed as a group median evaluated by using the mann - whitney rank sum test .
we analyzed 9 consecutive patients who underwent less - p between july 2009 and april 2010 .
the clinical data were compared with data from 18 patients out of 31 consecutive patients who underwent cl - p from november 2003 to april 2009 .
the 9 less - p patients were matched 1:2 with the 18 cl - p patients on the basis of age and side of surgery .
the choice of operation was based on the presence of obstruction on the diuretic renogram with either symptoms ( urinary tract infection , recurrent pain , or stone formation ) or functional impairment of the kidney ( relative uptake 40% ) .
all less - p procedures were performed by a single surgeon ( d.h.h . ) , whereas the cl - p procedures were performed by two surgeons ( 17 cases by d.h.h , 1 case by s.s.j . ) in both groups , the operating procedures were performed similarly , except for the number of access points .
a ureteral stent was placed antegradely , except in cases where the stent had been placed before surgery . to perform less - p ,
we used a wound retractor ( alexis ; applied medical , rancho santa margarita , ca , usa ) and a surgical glove as the homemade single - port device as described in our previous series . to make a single port similar to that of a commercial multichannel trocar ,
we firmly fastened the first , third , and fifth glove finger tips to the end of the three trocars ( two 12 mm trocars and one 5 mm trocar ) with a tie or rubber band .
pneumoperitoneum was made by co2 gas insufflation to 14 mm hg , and a 10 mm rigid laparoscope angled at 30 degrees was inserted .
the operation was performed by using conventional laparoscopic straight working instruments and 5 mm articulating instruments ( autonomy laparo - angle ; cambridge endo , framingham ma , usa ) to overcome the lack of triangulation that occurs with a single port .
we also used additional needlescopic instruments with a 2 mm trocar inserted at the subcostal area to create an environment similar to that for conventional laparoscopic pyeloplasty with ureteropelvic anastomosis ( fig . 1 , 2 ) .
the 2 mm grasper was used to assist with suturing by manipulating the renal pelvis or ureter and adjusting the needle direction ( fig .
the anastomosis was performed by means of a continuously running suture with 4 - 0 polygalactin suture .
a ureteral stent was inserted antegradely through the 2 mm trocar by using a 5 fr .
the 2 mm trocar site did not need to be closed after the operation . in the cl - p group
all patients underwent placement of a jackson - pratt drain through a 5 mm trocar incision in all cl - p cases and through the margin of the umbilical incision in all less - p cases .
prophylactic antibiotics were routinely prescribed . for pain control , we prescribed intravenous ( iv ) patient - controlled analgesia ( pca ) .
infusion of 1,500 g of fentanyl in 100 ml of normal saline was started at a basal infusion rate of 1.0 ml / hr with an iv infusion pump ( automed3200 ; ace medical , seoul , korea ) .
the analgesic bolus of pca ( using a 1.0 ml bolus and a lockout time of 15 minutes in the iv pca group ) was started at the post - anesthesia care unit by the patient after awakening .
additional mso4 was applied when the iv pca was ineffective at reducing or eliminating the pain .
the closed suction drain was subsequently removed if the drainage output did not increase and was less than 100 ml in 24 hours after foley catheter removal .
the perioperative parameters including operative time , intraoperative estimated blood loss , analgesic use , postoperative hospital stay , complications , and success rates were compared between the two groups .
the operative time was recorded from the time of the initial skin incision to the final skin suture . to compare postoperative pain
, we used a numerical rating scale ( nrs ) from 0 ( no pain ) to 10 ( worst possible pain ) , and we looked at the additional mso4 requirement on postoperative day 1 and the discharge day .
the assessment of success was based on improvement in the diuretic renogram , including resolution of clinical symptoms .
numerical data from a normal distribution were expressed as a group mean with the standard deviation and were compared by using the student 's t - test .
numerical data from a non - normal distribution were expressed as a group median evaluated by using the mann - whitney rank sum test .
the demographics of the patients in the cl - p and open less - p group are shown in table 1 .
there were no significant differences between the 2 groups in terms of age , operation side , sex , body mass index , and crossing vessel .
the number of attempts at previous endoscopic management was significantly higher in the less - p ( p=0.029 ) group .
all cl - p procedures were completed successfully with no conversions to open surgery and all open procedures were performed as planned .
one conversion to cl - p was present in the less - p group because of severe adhesion resulting from previous endoscopic management and intraperitoneal operation .
there was no statistically significant difference in the conversion rate to other operations , however .
there was also no mortality in either the cl - p or the less - p group .
less - p was associated with a shorter operative time ( 252.2 vs. 309.7 minutes , p=0.044 ) and a lower nrs on postoperative day 1 ( 3.7 vs. 5.6 , p=0.024 ) .
however , there were no significant differences between the two groups in terms of length of stay , estimated blood loss volume , double j indwelling time , foley catheter indwelling time , mso4 requirement , nrs on the discharge day , conversion rate to another operation , or complication rate .
two minor adverse events developed in the less - p group : one case of transient gross hematuria and one case of an emergency room visit for pain that was not relieved by oral medication after discharge .
the success rate was 94% ( 17 of 18 cases ) in the cl - p group ( median 23 months ) and 100% ( 9 of 9 cases ) in the less - p group ( median 14 months ) .
there was no significant difference in the success rate between the two groups ( p=1.00 ) .
in the past 20 years , accumulating evidence has suggested that laparoscopic pyeloplasty is the standard of care in adults [ 3,13 - 15 ] .
several studies have shown a success rate of greater than 90% for the laparoscopic procedure , similar to that achieved with traditional open dismembered pyeloplasty [ 13 - 15 ] .
laparoscopic pyeloplasty is associated with a short hospital stay , decreased parenteral narcotic use , good cosmesis , and less postoperative pain [ 13 - 15 ] .
these include port site bleeding , incisional hernias , and postoperative pain caused by incisional wounds .
less was suggested on the basis of the assumption that reducing the number of port sites would reduce some of the problems with conventional laparoscopic surgery . since then , less has been used for various urological diseases and has been shown to be feasible and safe and to have a success rate comparable to that of conventional laparoscopic surgery .
previous reports comparing less with conventional laparoscopic nephrectomy have shown comparable results and potential cosmetic advantages .
recently , tracy et al reported the following comparative results between less - p and cl - p : operative time ( 202 vs. 257 minutes ) , estimated blood loss ( 35 vs. 85 ml ) , minor and major complications ( 14.3% vs. 14.3% , 21.4% vs. 10% , respectively ) , and success rates ( 96% vs. 100% ) .
these results demonstrated that less - p was safe and feasible and was able to achieve a similar success rate to that of cl - p with potent cosmesis .
however , less is still a challenging procedure , especially for reconstructive surgery , because incomplete triangulation and more complex motion of the articulating instruments limits effective suturing .
for that reason , an additional 2 mm or 5 mm trocar is generally used during less - p .
tracy et al used a temporary 5 mm port in all cases to aid in suturing and an additional 3 mm subxyphoid port for right - sided procedures for liver traction when necessary .
stein et al also used a 2 mm grasping instrument to aid in suturing . in our series , we also used a 2 mm needlescopic trocar in all less cases . because the needlescopic trocar is the same size as a veress needle , for which an incision is not needed for insertion , it does not make a puncture site scar after the operation .
we assumed that by using a 2 mm needlescopic trocar , the cosmetic objective of umbilical less , a hidden scar , could be achieved . in reality
it does not provide enough holding strength , does not have rotation function ( which means that the operator must rotate his or her wrist ) , and requires more effort and concentration to manipulate the instrument because of the small jaw .
however , despite these limitations , the instrument provided powerful support during our less - p .
this approach supports an environment similar to that of cl - p : it provided effective traction of the bowel or liver and assisted with suturing by making triangulation .
the 2 mm trocar made it easy to place a ureteral stent antegradely because it could keep the guide wire and ureter in a line .
using a 3 mm instrument instead of a 2 mm one may be a better choice for overcoming the disadvantages of the 2 mm instrument .
however , the addition of a 2 mm trocar and grasper is still our routine practice for suturing in less pyeloplasty because use of the 2 mm trocar and grasper is feasible and the cosmetic effect is better .
our study showed comparable results between less - p with an additional 2 mm trocar and conventional laparoscopic surgery .
there were no significant differences in length of stay , estimated blood loss , mso4 requirement , or nrs on the discharge day .
our data also showed that the mean nrs on postoperative day 1 in the less - p group was lower than that in the cl - p group ( 3.7 vs. 5.6 , p=0.024 ) .
we can not precisely explain this result , but we assume that the fewer number of incisions helped to decrease the early postoperative pain . however , the pain gradually decreased throughout the hospital stay period , and when the patients were discharged , there was no significant difference .
these data suggest that less - p may result in less pain than cl - p during the early postoperative period . in this retrospective study ,
this use of pca may have affected the difference in postoperative pain between the two groups .
if pca had not been used , there might have been a greater difference in pain severity between the groups . in this study ,
less - p could be effectively performed compared with cl - p with minimal complications and a low conversion rate .
the mean operation time in the less group was even shorter than that in the cl - p group ( 252.2 min vs. 309.7 minutes , p=0.044 ) .
however , this may be from the time difference in the operation period . accumulated experience with intracorporeal suturing may have a decisive effect on the operation time in the less group . despite the time difference , this result demonstrates that less - p could be performed effectively by experienced laparoscopic surgeons .
less - p has a potential cosmetic advantage , but we were unable to assess the cosmetic advantage . despite inserting a jackson - pratt drain at the umbilicus , we effectively hid the surgical scar within the umbilicus during the less - p procedure . furthermore
it is obvious that a hidden scar has a cosmetic advantage over an exposed cl - p scar ( fig .
4 ) , but further studies with a validated cosmetic scale are necessary to address this issue
. there are several important limitations of our study that should be acknowledged , including the retrospective design with its inherent problems , the small number of patients , and the short - term follow - up period .
nevertheless , we consider this study to be valuable because we could show less pain in the less - p group during the early postoperative period in a matched control design study .
issues such as return to everyday activities and cosmesis remain important outcomes that should be addressed by future studies to provide further insight .
also , the role of less pyeloplasty needs to be further confirmed by a prospective randomized study with a large number of cases and a long - term follow - up .
less - p is a technically feasible and safe procedure with the addition of 2 mm instruments to overcome associated difficulties . in our study series ,
the surgical outcomes of less - p were comparable to those of cl - p .
in addition , less - p could decrease early postoperative pain . however , functional outcome data with long - term follow - up are needed to establish whether less pyeloplasty should be the standard option for upjo treatment .
 purposedespite a recent surge in the performance of laparoendoscopic single - site surgery ( less ) , concerns remain about performing less pyeloplasty ( less - p ) because of the technical difficulty in suturing . 
 we report our techniques and initial experiences with less - p using additional needlescopic instruments and compare the results with conventional laparoscopic pyeloplasty ( cl - p).materials and methodsnine patients undergoing less - p were matched 2:1 with regard to age and side of surgery to a previous cohort of 18 patients who underwent cl - p . in both groups , the operating procedures were performed equally except for the number of access points . in the less - p group , we made a single 2 cm incision at the umbilicus and used a homemade port . 
 we also used additional 2 mm needlescopic instruments at the subcostal area to facilitate suturing and the ureteral stenting.resultsthe preoperative characteristics were comparable in both groups . 
 postoperatively , no significant differences were noted between the less - p and cl - p cases in regard to length of stay , estimated blood loss , analgesics required , and complications . 
 but , less - p was associated with a shorter operative time ( 252.2 vs. 309.7 minutes , p=0.044 ) and less pain on postoperative day one ( numeric rating scale 3.7 vs. 5.6 , p=0.024 ) . 
 the success rate was 94% with cl - p 
 ( median , 23 months ) and 100% with less - p ( median , 14 months).conclusionsour initial experiences suggest that less - p is a feasible and safe procedure . the use of additional 2 mm instruments can help to overcome the difficulties associated with less surgery . 
INTRODUCTION
MATERIALS AND METHODS
1. Patients
2. Surgical technique
3. Statistical analysis
RESULTS
DISCUSSION
CONCLUSIONS