BackgroundTransurethral resection of the prostate (TURP) is a well-established surgical method for treatment of men with lower urinary tract symptoms (LUTS) secondary to benign prostatic obstruction (BPO). This has traditionally been provided as monopolar TURP (MTURP), but morbidity associated with MTURP has led to the introduction of other surgical techniques. In bipolar TURP (BTURP), energy is confined between electrodes atthe site ofthe resectoscope, allowing the use of physiological irrigation medium. There remains uncertainty regardingdifferences between these surgical methods in terms of patient outcomes.ObjectivesTo compare the effects of bipolar and monopolar TURP.Search methodsA comprehensive systematic electronic literature search was carried out up to 19 March 2019 via CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, PubMed, and WHO ICTRP. Handsearching of abstract proceedings of major urological conferences and of reference lists of included trials, systematic reviews, and health technology assessment reports was undertaken to identify other potentially eligible studies. No language restrictions were applied.Selection criteriaRandomised controlled trials (RCTs) that compared monopolar and bipolar TURP in men (> 18 years) for management of LUTS secondary to BPO.Data collection and analysisTwo independent review authors screened the literature, extracted data, and assessed eligible RCTs for risk of bias. Statistical analyses were undertaken according to the statistical guidelines presented in the Cochrane Handbook for Systematic Reviews of Interventions. The quality of evidence (QoE) was rated according to the GRADE approach.Main resultsA total of 59 RCTs with 8924 participants were included. The mean age of included participants ranged from 59.0 to 74.1 years. Meanprostate volume ranged from 39 mL to 82.6 mL.Primary outcomesBTURP probably results in little to no difference in urological symptoms, as measured by the International Prostate Symptom Score (IPSS) at 12 months on a scale of 0 to 35, with higher scores reflecting worse symptoms (mean difference (MD) -0.24, 95% confidence interval (CI) -0.39 to -0.09; participants = 2531; RCTs = 16; I2 = 0%; moderate certainty of evidence (CoE), downgraded for study limitations), compared to MTURP.BTURP probably results in little to no difference in bother, as measured by health-related quality of life (HRQoL) score at 12 months on ascale of 0 to 6, with higher scores reflecting greater bother(MD -0.12, 95% CI -0.25 to 0.02; participants = 2004; RCTs = 11; I2 = 53%; moderateCoE, downgraded for study limitations), compared to MTURP.BTURP probably reduces transurethral resection (TUR) syndrome events slightly (risk ratio (RR) 0.17, 95% CI 0.09 to 0.30; participants = 6745; RCTs = 44; I2 = 0%; moderate CoE, downgraded for study limitations), compared to MTURP. This corresponds to 20 fewer TUR syndrome events per 1000 participants (95% CI 22 fewer to 17 fewer). Secondary outcomesBTURP may carry a similar risk of urinary incontinence at 12 months (RR 0.20, 95% CI 0.01 to 4.06; participants = 751; RCTs = 4; I2 = 0%;low CoE, downgraded for study limitations and imprecision), compared to MTURP. This corresponds to four fewer events of urinary incontinence per 1000 participants (95% CI five fewer to 16 more).BTURP probably slightly reduces blood transfusions (RR 0.42, 95% CI 0.30 to 0.59; participants = 5727; RCTs = 38; I2 = 0%; moderate CoE,downgraded for study limitations), compared to MTURP. This corresponds to 28 fewer events of blood transfusion per 1000 participants (95% CI 34 fewer to 20 fewer). BTURP may result in similar rates of re-TURP (RR 1.02, 95% CI 0.44 to 2.40; participants = 652; RCTs = 6; I2 = 0%; low CoE, downgraded for study limitations and imprecision). This corresponds to one more re-TURP per 1000 participants (95% CI 19 fewer to 48 more). Erectile function as measured by the International Index of Erectile Function score (IIEF-5) at 12 months on a scale from 5 to 25, with higher scores reflecting better erectile function, appears to be similar(MD0.88, 95% CI-0.56 to 2.32; RCTs = 3; I2 = 68%; moderate CoE, downgraded for study limitations) for the two approaches.Authors' conclusionsBTURP and MTURP probably improve urological symptoms, both to a similar degree. BTURP probably reduces both TUR syndrome and postoperative blood transfusion slightly compared to MTURP. The impact of both procedures on erectile function is probably similar. The moderate certainty of evidence available forthe primary outcomes ofthis review suggests thatthere is no need forfurther RCTs comparing BTURP and MTURP.