nephron - sparing treatments have been considered as the best therapeutic strategy for localized renal cell carcinoma ( rcc ) , and these procedures have gained popularity . the application of renal ablative treatments , including radiofrequency ablation and cryoablation , has been increasing . these approaches preserve renal function , shorten the duration of hospital stay , and result in early convalescence . however , these treatments have limitations such as the lack of pathologic tumor assessment and uncertain long - term oncologic outcomes . although its oncological outcomes are equivalent to those of radical nephrectomy for localized rcc , partial nephrectomy has advantages over radical nephrectomy [ 3 - 5 ] . patients undergoing radical nephrectomy have a significantly higher chance of developing chronic renal insufficiency than do those undergoing partial nephrectomy . the incidence of renal insufficiency over time is significantly greater in patients undergoing radical nephrectomy . herein , we present our early experiences of robotic partial nephrectomy ( rpn ) procedures performed at our institution and compare the operative outcomes of rpn with those of lpn . between february 2009 and june 2010 , 13 patients underwent transperitoneal rpn ( group 1 ) and 14 patients underwent transperitoneal lpn ( group 2 ) by a single surgeon . the patients were diagnosed with rcc or angiomyolipoma ( aml ) indistinguishable from rcc in radiologic studies . the operative methods were chosen after obtaining informed consent and agreement for the charges for the operations from the patients . rpn was performed with the da vinci s system ( intuitive surgical , sunnyvale , ca , usa ) . in case of a centrally located tumor , a ureteral stent the patients were placed in a 70-degree lateral position under 14 mmhg of co2 gas insufflation . usually , 3 robotic ports and 1 assistant port were used . in cases of a tumor in the upper pole of the right kidney , an additional robotic trocar ( the third robotic arm ) 1 ) . in addition , a 30-degree , 10 mm robotic camera was used . the patient cart with robotic arms approached the patient posteriorly . the renal vein was not clamped . before tumor excision , 12.5 g of mannitol was administered intravenously . after removal of the tumor , a frozen biopsy of the tumor bed was performed . the renal parenchyma with capsule was sutured with vicryl 2 - 0 attached to hem - o - lok clips ( weck closure systems , research triangle park , nc , usa ) . the continuous suture was initiated from outside the renal parenchyma and continued to compress the renal parenchyma . hem - o - lok clips were placed after each throw of the running suture . finally , absorbable clips ( lapra - ty , ethicon inc . , somerville , nj , usa ) were applied instead of tying knots ( fig . 2 ) . after confirmation of hemostasis , a fibrin sealant ( tisseel , baxter ag , vienna , austria ) and a cellulose mesh ( surgicel , ethicon inc . , the patients ' records were reviewed retrospectively . to compare the operative results of the 2 groups , the mann - whitney u test and fisher 's exact test were used . , chicago , il , usa ) , with p - values<0.05 considered to indicate statistical significance . the characteristics of the patients who underwent rpn ( group 1 ) or lpn ( group 2 ) are presented in table 1 . four cases ( 30.8% ) in group 1 had a history of abdominal operations , including inguinal herniorrhaphy , laparoscopic hemicolectomy , appendectomy , and laparoscopic renal cyst excision . five cases ( 35.7% ) in group 2 had a history of abdominal operations , including transvaginal hysterectomy , transabdominal hysterectomy , laparoscopic partial nephrectomy , and laparoscopic cholecystectomy . the mean operative time was 153.222.3 minutes and 117.532.0 minutes in groups 1 and 2 , respectively ( p=0.003 ) . the mean robotic console time of group 1 was 101.221.5 minutes , and the mean laparoscopic time of group 2 was 86.832.3 minutes ( p=0.139 ) . the definition of the laparoscopic time was from insertion of the laparoscopic instruments to removal of the instruments . although the operative time of rpn was longer than that of laparoscopy , the differences in robotic console time and laparoscopic time were not significant . the mean warm ischemic time was 35.38.5 minutes and 36.46.8 minutes in 9 patients of group 1 and 10 patients of group 2 , respectively ( p=0.823 ) . the mean estimated blood loss in groups 1 and 2 was 283.6113.5 ml and 264.1163.7 ml , respectively ( p=0.382 ) . transfusion was performed in 2 patients ( 15.4% ) in group 1 ( p=0.222 ) . postoperative pain control was achieved by patient - control analgesia with morphine ( 40 mg ) and ketorolac ( 150 mg ) for 2 days . additionally , pethidine hcl was administered at mean dosages of 3.38.8 mg and 3.512.0 in groups 1 and 2 , respectively ( p=0.299 ) . the mean times to postoperative initiation of ambulation were 1.20.4 days and 1.20.4 days ( p=0.920 ) , and the times to initiation of oral intake were 1.20.4 days and 1.10.3 days ( p=0.504 ) in groups 1 and 2 , respectively . the mean length of hospital stay in groups 1 and 2 was 6.21.8 days and 5.30.6 days , respectively ( p=0.290 ) ( table 2 ) . the mean tumor size was 2.71.2 cm and 2.01.2 cm in groups 1 and 2 ( p=0.035 ) . pathologic results showed 11 cases of rcc and 2 cases of aml in group 1 , and 9 cases of rcc , cases of aml , and 1 case of oncocytoma in group 2 ( p=0.785 ) . open partial nephrectomy ( opn ) is one of the standard modalities of nephron - sparing surgery . long - term follow - up results of opn for localized rcc have shown acceptable cancer control effects [ 6 - 8 ] . however , the postoperative recovery period of opn is similar to that of open radical nephrectomy because of the morbidity due to the large flank incision . the number of lpns has steadily increased since its introduction by winfield et al in 1993 . the indications are expanded to more challenging cases , however , including central and hilar tumors , endophytic tumors , tumors greater than 4 cm , tumors in solitary kidneys , and tumors in patients with compromised renal function . concerning oncological outcomes , the 5-year cancer - specific survival rate for t1 rcc was more than 90% in a multicenter study . lpn has surgical and functional outcomes similar to those of opn in addition to comparable oncological outcomes . gill et al presented a comparative study of lpn and opn , in which lpn had shorter operating time , less estimated blood loss , shorter hospital stay , and longer warm ischemic time . marszalek et al demonstrated that lpn had shorter warm ischemic time , hospital stay , and operating time in 200 patients undergoing either lpn or opn . . however , lpn still has a steep learning curve to overcome the technical challenges of complete tumor excision with hemostasis and renal reconstruction in a limited renal ischemic time . it can offer a magnified , three - dimensional view and fully - articulating wristed instruments and enables surgeons to perform difficult operations . aron et al presented no proven advantages of rpn over lpn in 12 matched - pair patients . however , due to advances in the surgical technique , favorable operative results and intermediate - term outcomes have been demonstrated in recent reports . the positive surgical margin rate ranged from 0% to 2.3% [ 17 - 23 ] . rpn has advantages in the treatment of complex tumors such as endophytic , hilar , and multiple tumors . rogers et al reported the feasibility of rpn for hilar tumors in 11 patients in a multi - institutional analysis . even though the feasibility and safety of rpn has been proven , it does have drawbacks , including the lack of haptic feedback , dependency on an assistant , and high operating costs . long - term functional and oncological outcomes are needed to make rpn a standard treatment for small renal tumors . our initial experience with rpn showed acceptable operative outcomes comparable with those of previous reports [ 15 - 23 ] one of the reasons was that the patients required a longer stay under the korean health care system . although the operative time of rpn was longer than that of lpn , there was no significant difference in robotic console time and laparoscopic time . it might take some time to connect the robotic surgical system to the patient in the rpn group . the reasons for the long ischemic time might be the insertion time of suture materials and inexperienced assistants . if we had found a remnant cancer , we would have performed a radical nephrectomy . they had intraperitoneal adhesions from previous abdominal operations , which led to incomplete arterial dissections and clampings and bleeding . we did not find advantages in the operative results of rpn , which will require further accumulation of experience and technical developments . we used a sliding - clip renorrhaphy for calyceal reconstruction and parenchymal compression . when placing the hem - o - lok clips , it is necessary to pull the suture taut and then push the clip snug against the renal parenchyma . after completion of the suture and confirmation of hemostasis , a fibrin sealant and cellulose mesh were applied to the suture site . finally , a third layer suture of the fascial covering was performed . this technique has certain advantages , including effective hemostasis , decreased dependence on assistance , and decreased operation and warm ischemic time . furthermore , long - term follow - up is needed to identify oncologic and functional outcomes of rpn . our experiences showed that rpn was technically feasible , and its operative outcomes were comparable to those of lpn . although the operative time of rpn was longer than that of lpn , there was no significant difference in operative outcomes , including robotic console time and laparoscopic time . to identify advantages of rpn , we must accumulate more experience and make further technical developments . further studies with long - term follow - up of rpn are also needed to make rpn a standard treatment for localized rcc .
purposeto determine the feasibility and safety of robotic partial nephrectomy ( rpn ) , we compared the operative outcomes of patients who had undergone rpn with those of patients who had undergone laparoscopic partial nephrectomy ( lpn).materials and methodsbetween february 2009 and june 2010 , 13 patients underwent transperitoneal rpn ( group 1 ) and 14 patients underwent transperitoneal lpn ( group 2 ) by a single surgeon . 
 the operative outcomes of the 2 groups were compared by using mann - whitney u and fisher 's exact tests.resultsall cases were completed successfully without conversion to open surgery . 
 the mean operative time was 153.222.3 and 117.532.0 minutes in groups 1 and 2 , respectively ( p=0.003 ) . 
 the mean robotic console time of group 1 was 101.221.5 minutes , and the mean laparoscopic time of group 2 was 86.832.3 minutes ( p=0.139 ) . 
 the mean warm ischemic time was 35.38.5 minutes and 36.46.8 minutes in groups 1 and 2 , respectively ( p=0.823 ) . 
 the mean estimated blood loss was 283.6113.5 ml and 264.1163.7 ml ( p=0.382 ) , respectively . 
 the mean length of hospital stay was 6.1 and 5.3 days ( p=0.290 ) , respectively . 
 the mean tumor size was 2.71.2 cm and 2.01.2 cm ( p=0.035 ) , respectively . 
 the surgical margins were negative in all cases.conclusionsalthough the operative time of rpn was longer than that of lpn , there were no significant differences in operative outcomes including robotic console time and laparoscopic time between the procedures .