benign prostatic hyperplasia ( bph ) is the most common benign tumor in men , and its incidence is age - related . symptoms of bph are caused by either obstructive components of the prostate glands or secondary changes to the bladder resulting from bladder outlet obstruction . there are many treatment alternatives , such as watchful waiting , pharmacologic medications , phytotherapy , minimally invasive therapy , transurethral resection of prostate ( turp ) , and open simple prostatectomy . surgical management is often required when the symptoms induced by bph are refractory to pharmacologic treatments . in those cases , turp is the most frequently performed procedure for endoscopic management owing to its shorter hospitalization and low comorbidity and mortality . however , if the prostate gland is too large , conventional monopolar turp has limitations , such as prolonged operation time with use of non - electrolyte irrigation fluid and monopolar current , which can result in transurethral resection ( tur ) syndrome and an increased risk of bleeding . presently , there have also been a few reports regarding the utilization of turp with bipolar energy in cases of prostate glands over 100 ml . therefore , with three procedures being used to surgically treat bph and no clear agreement or comparison among the three , the purpose of this study was to compare the efficacy and safety of monopolar turp , bipolar turp , and open prostatectomy in large prostate glands . a retrospective study was conducted with 48 bph patients who underwent monopolar turp , bipolar turp , or open prostatectomy . exclusion criteria were abnormal digital rectal examination ( dre ) findings , elevated prostate - specific antigen ( psa ) , and presence of neurogenic bladder , urethral stricture , bladder stone , or tumor . among 48 bph patients with prostate glands larger than 100 ml , 19 patients underwent monopolar turp ( group a ) , 17 patients underwent bipolar turp ( group b ) , and 12 patients underwent open prostatectomy ( group c ) from january 2004 to june 2009 . in this study , all of the operations were performed by a single surgeon who had previously performed 143 cases of turp on prostates smaller than 100 ml . among the groups , 6 , 7 , and 4 patients , respectively , had concomitant diabetes mellitus ( dm ) . a total of 8 , 10 , and 7 patients from each group had at least one episode of acute urinary retention in the past . twenty - six patients had been on an alpha-1-adrenoreceptor blocker and 6 patients had been on a combination of an alpha-1-adrenoreceptor blocker and 5-alpha - reductase inhibitors for a mean duration of 1.2 months before the surgical interventions . monopolar turp was performed with a 24 fr resectoscope ( karl storz , tuttlingen , germany ) using urosol ( cj , seoul , korea ) . bipolar turp was performed with a 27 fr continuous flow resectoscope ( gyrus acmi , olympus inc , germany ) using saline irrigation with the gyrus plasma - kinetic tissue management system . at the end of the monopolar and bipolar turp , a 20 fr 3-way urethral foley catheter was inserted and normal saline irrigation was applied . continuous saline irrigation was done until the urine drained from the urethral foley catheter became clear in the absence of irrigation . in cases of open prostatectomy , a 20 fr 3-way urethral foley catheter and suprapubic cystostomy catheter were inserted with continuous saline irrigation at a minimal rate to prevent urine passage blockage . the patients were discharged upon spontaneous voiding . for the preoperative data , we collected the international prostate symptom score ( ipss ) , maximal flow rate ( qmax ) , prostate volume , intraoperative resected tissue volume , resection velocity , and operation time , which were recorded and analyzed . data collected postoperatively were the hemoglobin / sodium change , length of postoperative hospitalization , and postoperative 6-month ipss , quality of life ( qol ) , and qmax . the kruskal - wallis test , post hoc tamhane 's test , chi - square test , and wilcoxon signed - rank test were performed to analyze the data . all statistical analyses were performed with spss ver . 18.0 ( spss inc , chicago , il , usa ) . the preoperative prostate volumes of each group were 124.627.9 ml ( a ) , 117.918.6 ml ( b ) , and 131.421.0 ml ( c ) , respectively ( p=0.217 ) ( table 1 ) . the preoperative mean serum sodium concentrations of each group were 136.42.3 meq / l ( a ) , 137.82.2 meq / l ( b ) , and 140.02.0 meq / l ( c ) . the preoperative mean serum hemoglobin of each group were 14.30.8 meq / l ( a ) , 14.32.2 meq / l ( b ) , and 14.90.7 meq / l ( c ) ( table 2 ) . six patients from the monopolar turp group experienced a significant decrease in the serum sodium concentration . the mean operation time was 117.618.4 minutes ( a ) , 13249.8 minutes ( b ) , and 163.827.4 minutes ( c ) , respectively ( p=0.001 ) . resected prostatic tissue volumes were 32.611.2 ml ( a ) , 41.411.9 ml ( b ) , and 60.813.6 ml ( c ) ( p<0.001 ) . the resection velocity of groups a ( 0.28 ml / min ) and b ( 0.34 ml / min ) showed no statistically significant difference ( p=0.191 ) ( table 1 ) . postoperative hemoglobin changes in the three groups showed a statistical significance ( p<0.001 , p<0.001 , and p=0.002 ) . complications were noted in 5 cases in the monopolar turp group and in 4 cases in the open prostatectomy group . in the monopolar group , there were 2 cases of tur syndrome and 3 patients who required blood transfusions due to a mean reduction in hemoglobin of 4.2 g / dl . even though the changes in hemoglobin were statistically significant , there were no postoperative hemoglobin changes severe enough to necessitate blood transfusions in the bipolar group . in the open prostatectomy group , the transfusion rate of each group was 15% , 0% , and 33% , respectively . factors including the color of the urine drained from the urethral foley catheter and anemic conjunctiva postoperatively were triggers for deciding upon transfusion . postoperative hospital stays were 9.42.3 days , 6.31.3 days , and 12.02.9 days , respectively ( p<0.001 ) . patients in the bipolar turp group required shorter hospitalizations than did patients in the other groups . the postoperative 6-month ipss / qmax of all groups showed statistically significant improvement ( table 2 ) . no cases of urethral or meatal strictures were noted during the 6-month follow - up period in either turp group . alpha-1-adrenoreceptor blockers and 5-alpha - reductase inhibitors are the mainstay of treatment for bph and have been shown to have a higher cost - efficiency than turp . however , the most effective treatment modality is known to be the surgical resection of prostatic adenomas , which cause obstruction . open prostatectomy is considered when the prostate gland is too large to be resected endoscopically . previously , a prostate gland larger than 75 ml was an indication for open prostatectomy . concomitant bladder pathologies such as bladder diverticulum , bladder stones , urethral strictures , and a patient 's inability to be in the dorsal lithotomy position are other indications for open prostatectomy . park and chung reported that when comparing turp with open prostatectomy , open prostatectomy renders better postoperative ipps and a higher qmax than does turp due to the complete resection of adenomas , which leads to wider width and symmetry of the proximal prostatic urethra . open prostatectomy offers advantages such as a lower retreatment rate , more complete removal of prostate adenomas , and avoidance of tur syndrome . however , risks of incontinence , retrograde ejaculation , perioperative hemorrhage , and longer hospitalization still remain . conventional turp was first developed in the united states in the 1920s and 1930s . over the years , many advances in surgical instruments and technique have been made , and thus now turp is recognized as the gold standard for the surgical treatment of bph . turp is known to offer improvement in voiding symptoms and qmax in over 80% of patients . morbidities associated with turp have been decreasing over the past three decades . however , perioperative hemorrhage and tur syndrome , which is a consequence of excessive absorption of non - conductive irrigating solution , are still grave complications that can occur . the risk is increased if the gland is larger than 45 ml and the resection time is longer than 90 minutes . however , new technical advances to conventional turp with monopolar energy were made in early 2000 , most notably the development of bipolar current in turp . the most noticeable difference is that saline is used as an irrigant , which reduces the morbidities associated with tur syndrome . as shown in our results , bipolar turp when compared with monopolar turp resulted in a lower risk of developing tur syndrome due to a smaller change in serum sodium than with monopolar turp . this enables surgeons to take a longer time to operate and to resect more prostatic tissue than is possible with monopolar turp . moreover , bipolar turp seems to be more efficient for removing tissue and simultaneously controlling for bleeding when compared to monopolar turp . it is noteworthy that no transfusions were required in the bipolar turp group , whereas there were 3 transfusion cases in the monopolar turp group . also , when compared with the other groups , bipolar turp required shorter postoperative hospitalization . starkman et al reported that the patients treated with gyrus turp had their catheter removed a mean of 1.4 days earlier than the monopolar turp group . eaton and francis , reported that among 40 patients , 32 patients could be discharged on the day of operation with use of the gyrus system . de sio et al reported shorter catheterization and hospitalization for bipolar turp patients . in a multicenter study regarding bipolar turp , operators preferred bipolar turp over monopolar turp owing to cleaner resection surfaces ( 64% ) and higher accuracy when resecting the apex of the prostate glands ( 93% ) . considering that utilization of monopolar turp in large prostate glands is limited , bhansali et al compared bipolar turp with monopolar turp in their series of 70 patients with prostate glands > 60 ml and reported that bipolar turp showed excellent results in terms of perioperative blood loss , change in serum sodium , and duration of catheterization . baek et al reported perioperative outcomes of bipolar turp in patients with prostate glands > 80 ml in their series and found that bipolar turp showed advantages such as less serum sodium change and less hemoglobin change . in 2006 , kim et al reported that bipolar turp is superior to monopolar turp with fewer surgical complications . kim et al also stated that turp with bipolar energy rendered postoperative outcomes similar to those of monopolar turp but with fewer complications , shorter catheterization , shorter hospitalization time , and lower cost . unlike the above - mentioned reports , we studied only prostate glands larger than 100 ml and compared the perioperative parameters of monopolar and bipolar turp and open prostatectomy , which is indicated for prostate glands larger than 75 ml . the patients had not been on alpha-1-adrenoreceptor blockers or 5-alpha - reductase inhibitors for a long period of time , because it was hard to expect satisfactory alleviations of voiding symptoms with medication alone with a prostate gland size of larger than 100 ml . in this study , volumes of prostate weights resected were lower than those reported previously , especially in the open prostatectomy group . the lower volumes of prostatic tissue removed in this study can be accounted for by the smaller adenoma sizes in the open prostatectomy group compared with those of previous reports . in addition , the lower prostate weights removed in both turp groups may be accounted for by the surgeon 's experience rather than a cautery effect . despite the lower volumes of prostatic tissues removed than in previous literature , bipolar turp and open prostatectomy resulted in significantly improved postoperative 6-month qmax and ipss , showing no statistically significant difference between the two groups in postoperative change in qmax and ipss at the 6-month follow - up . one limitation of this study is that monopolar and bipolar turp were not performed with randomization . a second limitation of this study is that the size of the study population was relatively small . last , the patients were not randomized to exclude concomitant conditions , such as diabetes mellitus or episodes of acute urinary retention , that could have affected voiding symptoms . bipolar turp showed similar efficacy to monopolar turp and open prostatectomy in improving voiding symptoms while rendering shorter hospitalizations , a low transfusion rate , and fewer complications such as tur syndrome . bipolar turp can be considered as a safe substitute for monopolar turp and open prostatectomy even for large prostate glands over 100 ml .