various modalities , such as percutaneous nephrolithotomy ( pcnl ) , extracorporeal shock wave lithotripsy , and retrograde intrarenal surgery , are used to manage renal stone disease [ 1 - 3 ] . however , pcnl is regarded as the treatment of choice for most renal stones , especially for patients with a large renal stone ( > 2 cm ) , an infected stone , or a cystine stone and for those with a history of failed shock wave lithotripsy . general anesthesia during pcnl has many advantages , for example , it enables breathing control and improves patient comfort . however , associated complications and cost are higher for general anesthesia than for regional anesthesia . for example , endotracheal tube migration and neurologic problems , particularly at the time of position transition , may arise during pcnl under general anesthesia . unfortunately , few research studies have been conducted to compare regional and general anesthesia with respect to operative parameters . in the present study , therefore , to determine whether pcnl under regional anesthesia is a better alternative than pcnl under general anesthesia , we examined surgical outcomes after these two procedures . one hundred and one consecutive patients who underwent pcnl as a first - line management for renal stones , including staghorn , pelvic , and calyceal stones , from june 2004 to june 2013 at inje university sanggye paik hospital were included in this retrospective study . the patients were classified into two groups by anesthesia method : a regional anesthesia group ( n=77 ) and a general anesthesia group ( n=24 ) . decisions regarding anesthesia method were mainly based on considerations of medical status , such as cardiac problems and the presence of respiratory illness or coagulopathy . in the absence of such factors , the contraindications for pcnl were uncorrected coagulopathy , congenital renal anomaly , and metastatic malignancy . in addition to history taking , we performed a physical examination , preoperative laboratory tests , and a radiological evaluation , which included plain radiography of the kidney - ureter - bladder ( kub ) region and abdominopelvic computed tomography ( ct ) . stone size was defined as the sum of the maximal lengths of renal stones on ct images . patients with a urinary tract infection were treated preoperatively in accordance with urine culture sensitivity . the clinical and stone parameters compared were age , gender , body mass index , stone laterality , stone size , and stone number , respectively . regional anesthesia was induced with 0.5% heavy bupivacaine ( marcaine , astrazeneca korea , seoul , korea ) 12 ml , and a spinal epidural set ( portex , smiths medical , kent , uk ) was injected intrathecally into the l3 - 4 or l4 - 5 interspaces . the level of anesthesia was checked for 5 minutes after injection with the patient in the trendelenburg position . if surgery was prolonged , levobupivacaine ( chirocaine , abbott korea , seoul , korea ) was administered by an anesthesiologist to maintain adequate anesthesia . general anesthesia was carried out by using intravenous propofol ( pofol , dongkook pharmaceutical co. , seoul , korea ) and rocuronium ( esmeron , msd korea , seoul , korea ) . following the induction of anesthesia an occlusion ureteral catheter was then inserted into the renal pelvis and ballooning ( 1 ml ) was performed to prevent stone fragments from descending into the proximal ureter . patients were then rotated to the prone position and percutaneous nephrostomy was performed under ultrasonographic guidance . the access tract was dilated with an amplatz and a balloon dilator , and stone fragmentation was performed by using a combination of ultrasonic and pneumatic lithotripsy . stone fragments were removed by using grasping forceps under a 24-fr nephroscope . a 20-fr nephrostomy tube was left and a fluoroscopic nephrostogram was routinely obtained to assess status at the end of the procedure . patients in both groups were radiologically followed up at 1 day ( initial ) and 1 month ( overall ) after surgery to assess status . stone - free status was defined as the absence of any fragment greater than 4 mm by kub . operative outcomes , surgical times , hospital stays , stone - free rates , perioperative complications , and changes in hemoglobin and white blood cell counts were compared by using the modified clavien grading system , which was proposed to grade perioperative complications of general surgery and has been validated in a cohort of 6,336 patients . fever was defined as a temperature exceeding 37.7 at 1,600 on the first postoperative day . postoperative antipyretics ( arthagyl , ilyang pharmaceutical co. , seoul , korea ) , analgesics ( tridol , yuhan co. , seoul , korea ) , antiemetics ( mexolon , donga pharm , seoul , korea ) , and diuretics ( lasix , handok inc . , seoul , korea ) were injected intravenously when symptoms appeared during the operative or first postoperative day . blood transfusions were done in the operating room on the basis of decisions made by anesthesiologists . chicago , il , usa ) . because the number of patients in the general anesthesia group was small ( n=24 ) , continuous variables were assessed by using the mann - whitney test , and categorical variables were analyzed by using the chi - square test . clinical parameters are expressed as meanstandard deviations , and statistical significance was accepted for p - values < 0.05 . patient and stone characteristics in the regional and general anesthesia groups are compared in table 1 . mean ages in these groups were 54.812.2 years and 50.817.8 years , respectively ( p=0.338 ) . gender and body mass index were nonsignificantly different , and mean stone sizes ( 34.524.0 mm and 42.336.1 mm , respectively ; p=0.309 ) , mean stone numbers ( 2.02.4 and 2.95.1 , respectively ; p=0.648 ) , and the distributions of renal stones were similar ( p=0.254 ) . intergroup differences between initial stone - free rates ( 68.8% and 41.7% , respectively ; p=0.246 ) and overall stone - free rates ( 80.5% and 66.7% , respectively ; p=0.371 ) were nonsignificantly different . no significant intergroup differences were found between mean surgical times ( 14372 minutes and 151112 minutes , respectively ; p=0.185 ) or changes in hemoglobin levels ( -1.61.2 g / dl and -1.71.3 g / dl , respectively ; p=0.734 ) in the regional and general anesthesia groups . furthermore , white blood cell levels were not significantly changed in the two groups ( 3,8833,110/l and 3,9103,509/l , respectively ; p=0.480 ) . however , mean hospital stay was significantly shorter in the regional anesthesia group ( 8.93.2 days vs. 11.56.9 days , respectively ; p=0.025 ) . perioperative complications were investigated by using the modified clavien grading system , and the results are summarized in table 2 . a smaller proportion of patients in the regional anesthesia group experienced postoperative fever ( p=0.007 ) . however , mean dosages of antipyretics ( p=0.397 ) , analgesics ( p=0.800 ) , antiemetics ( p=0.179 ) , and diuretics ( p=0.737 ) administered were not significantly different . furthermore , the mean number of pints of blood transfused per patient was similar in the two groups ( 0.30.9 vs. 0.30.7 , respectively ; p=0.811 ) . no patient experienced a grade iii or iv complication according to the modified clavien grading system . pcnl remains the first - line treatment of choice for managing renal stone disease , although minimally invasive modalities , such as retrograde intrarenal surgery , have been introduced . furthermore , most urologists prefer general anesthesia for pcnl owing to the high level of anesthesia achieved , the ability to control the patient 's breathing , and because it is more comfortable for patients . however , general anesthesia is more likely to cause severe morbidities , such as drug - induced anaphylaxis , complications associated with endotracheal tube insertion , and cardiovascular , pulmonary , and neurologic complications , than is regional anesthesia . studies have been conducted to demonstrate the benefits of regional anesthesia in other types of surgery , such as radical retropubic prostatectomy   and total hip arthroplasty . salonia et al .   asserted that regional anesthesia permits fine muscle relaxation and achieves excellent surgical outcomes after radical retropubic prostatectomy . furthermore , regional anesthesia has been reported to reduce the risk of intraoperative hemorrhage , to be associated with less postoperative pain , and to allow earlier restoration than general anesthesia [ 18 - 20 ] . in addition , gonano et al .   reported that the cost of regional anesthesia is 40% less than that of general anesthesia during orthopedic surgeries . several comparative studies on anesthesia methods in pcnl have demonstrated various benefits for pcnl under regional anesthesia compared with general anesthesia . in a retrospective comparative study of 37 patients who underwent regional anesthesia and 45 who underwent general anesthesia , it was concluded that the results were comparable in terms of general profiles , operative times , and stone - free rates . in another study of 50 patients who underwent pcnl , regional anesthesia was found to be associated with greater patient satisfaction , less early postoperative pain , and fewer adverse events than general anesthesia . furthermore , in a prospective randomized study on pcnl in 64 patients ( 32 general and 32 regional anesthesia ) , patients in the regional anesthesia group were found to have significantly lower postoperative analgesic demands and shorter hospitalization periods . reported that general anesthesia increases the probabilities of fluid absorption and electrolyte imbalance , and other authors have recommended regional anesthesia for patients with an electrolyte imbalance , especially for morbidly obese patients . despite the opinion held by some that regional anesthesia is unsuitable for pcnl of calculi in the upper pole of the kidney , regional anesthesia ( bupivacaine [ marcaine ] , 12 - 15 mg ) can be used to anesthetize up to the t4 level ( level of axilla ) according to an anesthesiology textbook . general anesthesia is associated with significant changes in the shape of the chest and alveolar gas contents . outside of that , these changes result in continued elevation of the risk for reintubation , mechanical ventilation , and nosocomial pneumonia , all of which prolong the hospital stay . regarding hospital stay , it was previously reported that average hospital stay is approximately 5 to 7 days regardless of anesthesia type . however , in the present study , hospital stays were 8.93.2 days and 11.56.9 days , respectively , which could have been due to the exclusion of time spent at the hospital before surgery and the procedure used to determine the discharge date . in addition , according to a large - scale study , initial and overall stone - free rates were 69.9% and 88.8% , respectively , and another study conducted on 610 patients found corresponding rates of 57.6% and 84.9% , respectively . in the present study , values were 68.8% and 80.5% in the regional anesthesia group and 42.9% and 71.4% in the general anesthesia group , which were relatively low and did not represent a significant intergroup difference . we attribute these differences to the different definitions used for the stone - free rate and patient descriptive features . in brief , this retrospective study showed that despite similar patient characteristics in the two groups , postoperative fever rates and hospital stays were significantly greater in the general anesthesia group . thus , it may be more helpful for patients to implement pcnl under regional anesthesia than general anesthesia in matters of fever control and cost of hospitalization . the present study had some limitations that deserve mention . first , it was inherently limited by its retrospective design ; as such , lack of control of basic patient factors may have introduced bias . second , the study was performed at a single center , and the general anesthesia group was appreciably smaller than the regional anesthesia group . the present study showed that in terms of general characteristics and procedural success , the outcomes of pcnl conducted by use of regional or general anesthesia are similar . nevertheless , pcnl with regional anesthesia required fewer hospital days and was associated with a lower postoperative fever rate . accordingly , we conclude that pcnl under regional anesthesia is at least as advantageous as pcnl under general anesthesia in patients with kidney calculi .