|Year : 2020 | Volume
| Issue : 7 | Page : 1588-1595
Efficacy and safety of bipolar versus monopolar transurethral resection of bladder tumors: A meta-analysis of randomized controlled trials
Yanjie Ma1, Libin Sun1, Xueming Lin1, Wei Zhang1, Dongwen Wang2
1 Department of Urology, First Hospital of Shanxi Medical University; First College of Clinical Medicine, Shanxi Medical University, Taiyuan, Shanxi, China
2 First College of Clinical Medicine, Shanxi Medical University, Taiyuan, Shanxi; Department of Urology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, China
|Date of Submission||27-Apr-2020|
|Date of Decision||13-Jul-2020|
|Date of Acceptance||20-Oct-2020|
|Date of Web Publication||9-Feb-2021|
No. 85 South Jiefang Road, 030001, Taiyuan
Source of Support: None, Conflict of Interest: None
Context: In the management of bladder tumors bipolarenergy has been used as a common alternative to the conventional monopolar transurethral resection of the bladder (M-TURB).
Aim: This study aims to examine the clinical efficacy and safety of bipolar versus monopolar TURB tumors (TURBTs).
Subjects and Methods: We conducted a systematic literature search in the PubMed, Cochrane Library, and Embase databases for the identification of prospective randomized controlled trials (RCTs) that compared the outcomes between the two procedures.
The Statistical Tool: Meta-analysis was performed using the software Review Manager 5.3.
Results: We identified nine RCTs involving 1193 patients. In terms of the surgical outcomes, there was no significant difference between the bipolar and monopolar TURBT. However, there was significantly reduced bladder perforation (risk ratio [RR] = 0.48; 95% confidence interval [CI] = 0.30–0.77; P = 0.002) and shorter hospital stay (mean difference = 0.43; 95% CI = 0.83–0.03, P = 0.01) in the bipolar TURBT group. There was also a lower incidence of thermal damage, which causes histopathological artifacts for patients treated via bipolar TURBT relative to those treated via monopolar TURBT (RR = 0.66; 95% CI = 0.55–0.78; P < 0.00001). P < 0.05 was considered to be statistically significant. However, after bipolar and monopolar TURBT, we had no sufficient evidence regarding the recurrence rate.
Conclusion: This meta-analysis suggests that the use of bipolar technology, which is associated with less bladder perforation and lower thermal artifacts in TURBT is safer and more effective.
Keywords: Bipolar, bladder tumors, meta-analysis, monopolar, transurethral resection
|How to cite this article:|
Ma Y, Sun L, Lin X, Zhang W, Wang D. Efficacy and safety of bipolar versus monopolar transurethral resection of bladder tumors: A meta-analysis of randomized controlled trials. J Can Res Ther 2020;16:1588-95
|How to cite this URL:|
Ma Y, Sun L, Lin X, Zhang W, Wang D. Efficacy and safety of bipolar versus monopolar transurethral resection of bladder tumors: A meta-analysis of randomized controlled trials. J Can Res Ther [serial online] 2020 [cited 2021 Oct 26];16:1588-95. Available from: https://www.cancerjournal.net/text.asp?2020/16/7/1588/308768
| > Introduction|| |
Approximately 75% of patients with bladder cancer are presented with a disease confined to the mucosa (Stage Ta and carcinoma in situ) or submucosa (Stage T1)., Currently, transurethral resection of the bladder (TURB) remains a gold standard for the management of patients with nonmuscle invasive bladder cancer.
Compared with conventional monopolar resection, bipolar resection has been introduced to produce better specimens and reduce the risk of complications. At present, the results remain controversial.,,,,,,,,, In this meta-analysis, we systematically analyzed the results of published studies, thereby evaluating the efficacy and safety of bipolar TURB tumor (TURBT) versus monopolar TURBT.
| > Subjects and Methods|| |
The design and execution of this meta-analysis was conducted in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA). A systematic search of the PubMed, Embase, and Cochrane Library databases was performed to identify relevant studies published up to August 1, 2019. Search terms used include “Urinary Bladder Neoplasm” “bladder cancer” “bladder tumors” “transurethral resection” “monopolar,” and “bipolar.” Reference lists of the retrieved articles were further used to identify additional relevant studies. The searches were restricted to English publications.
Selection of studies
Studies were deemed eligible if they assessed patients with bladder tumors undergoing bipolar TURBT or monopolar TURBT to compare surgical outcomes (operative time, hemoglobin drop, catheterization time, hospital stay, thermal damage, blood loss requiring transfusion, TUR syndrome, obturator nerve reflex, bladder perforation, detrusor muscle sampling rate, and recurrence rate). Only randomized controlled trials (RCTs) were included. Studies not having primary data (i.e., commentaries, reviews, and letters) were excluded.
Data extraction and study quality assessment
Two reviewers independently extracted the following items: The first author, year of publication, country, study period, study design, number of patients undergoing bipolar TURB or monopolar TURB, and outcomes including efficacy and safety. By means of discussion, all disagreements were resolved using a third reviewer. The efficacy was assessed by catheterization time, hospital stay, operative time, thermal damage, detrusor muscle sampling rate, and recurrence rate. Safety was evaluated by obturator nerve reflex, bladder perforation, TUR syndrome, hemoglobin decrease, and transfusion. The level of evidence (LE) of included studies was rated according to Oxford LE Working Group 2011. The quality of the RCTs was determined using the Jadad Scale. A score of 2 or less was considered low, 3 was considered as intermediate, and 4-5 was considered high quality.
The meta-analysis was performed using the software Review Manager 5.3 provided by the Cochrane Library. P < 0.05 was considered to be statistically significant. Continuous variables were presented as mean difference (MD) with 95% confidence interval (CI), whereas the risk ratios (RRs) with 95% CI were calculated for dichotomous parameters according to the Mantel–Haenszel test.
The random-effects or fixed-effects method was used for data analysis. Statistical heterogeneity was assessed using the formal Q-statistic and I2-statistic, with the statistical significance level set at P < 0.05. An I2 <50% is considered as an acceptable level of heterogeneity therefore a fixed effect model was applied. The random-effects method was used to combine the results when I2 >50% was presented. In addition, sensitivity analyses were performed by omitting a certain study each time.
| > Results|| |
Characteristics of selected studies
Approximately 169 studies were identified by hand search and from the electronic database. Following the exclusion of 160 articles, nine studies (RCTs) were deemed fully eligible for meta-analysis.,,,,,,,, According to the PRISMA statement, study selection flow diagram is shown in [Figure 1]. Overall, 1193 cases were included (597 patients for bipolar TURBT and 596 for monopolar TURBT). The characteristics of these studies are shown in [Table 1].
Outcomes of efficacy
A lower incidence of thermal damage existed, which causes histopathological artifacts for patients treated via bipolar TURBT relative to those treated via monopolar TURBT (RR = 0.66; 95% CI = 0.55–0.78; P < 0.00001) [Figure 2]. The quantity and quality of thermal artifacts was reported in five studies. [Supplementary Table 1] shows the different evaluation measures of thermal damage in each study. There was no difference in the detrusor muscle sampling rates (RR = 1.06; 95% CI = 0.98–1.44; P = 0.16) [Figure 3]. A shorter hospital stay was recorded between the bipolar and monopolar TURBT (MD = 0.43; 95% CI = 0.83–0.03; P = 0.03) [Figure 4]. There were no statistically significant differences in operative time (MD = 1.22; 95% CI = 5.80–3.36; P = 0.60) [Figure 5], catheterization time (MD = 0.43; 95% CI = 1.12–0.25; P = 0.21) [Figure 6]. Two studies reported postoperative recurrence rate, which could not be performed because of the different follow-up period of the recurrence rate in each study. There was no significant difference in the 2-year recurrence-free survival rate between the groups. When comparing the two procedures no significant differences were observed in the recurrence rate after a 1-year follow-up.
|Figure 2: Forest plot and meta-analysis of thermal damage, which causes histopathological artifacts|
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|Figure 3: Forest plot and meta-analysis of the detrusor muscle sampling rates|
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There was no significant difference in terms of blood loss requiring transfusion (RR = 0.69; 95% CI = 0.27–1.78; P = 0.45) [Figure 7], TUR syndrome (RR = 0.26; 95% CI = 0.03–2.26; P = 0.22) [Figure 8], obturator nerve reflex (RR = 0.64; 95% CI = 0.39–1.06; P = 0.08) [Figure 9] between bipolar and monopolar TURBT. Pooled analysis revealed a lesser bladder perforation (RR = 0.48; 95% CI = 0.30–0.77; P = 0.002) [Figure 10] in the bipolar TURBT group; nine studies reported bladder perforation. Evaluation measures are not completely consistent. [Supplementary Table 2] shows the different evaluation measures of bladder perforation in each study. No significant difference in the hemoglobin drop was observed between the bipolar and monopolar TURBT (MD = 0.20; 95% CI = 0.47–0.48; P = 0.16) [Figure 11].
|Figure 7: Forest plot and meta-analysis of blood loss requiring transfusion|
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|Figure 8: Forest plot and meta-analysis of transurethral resection syndrome|
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Sensitivity analysis was performed by removing one of the included studies each time. When the study by Thirugnanasambandam and Ramanathan was obtained, the result of operative time showed a significantly statistical difference when comparing the two procedures (MD = 2.86; 95% CI = 3.97 − 1.76; P < 0.00001). When the study by Hashad et al. was obtained, the result of hospital stay showed no significant difference between the two groups (MD = 2.86; 95% CI = 3.97 − 1.76; P < 0.00001). Following the removal of a particular study, no other statistical difference in the pooled assessment was observed between the two groups.
| > Discussion|| |
TURBT is a crucial procedure as the base of diagnosis and initial therapy of bladder tumors. Since the introduction of TURBT in 1910, it has been performed using monopolar electrocautery. The aim of the initial resection is to provide safe and complete tumor resection. In addition, excessive tissue damage should be avoided to allow adequate pathological analysis. Monopolar systems used for TURBT require the use of high energy and voltage to permit the transmission of current from the loop to the skin. The heat generated from this current cause desiccation of small cells. Moreover, it is difficult to perform adequate histological assessment for severely cauterized tissues. Bipolar technology has been introduced and has a firm place in clinical practice among urologists. Bipolar resection excludes the patient from the electrical circuit and uses a physiological solution for irrigation instead of the hypotonic glycine, sorbitol, or mannitol, which helps alleviate TUR syndrome. In addition, the technique is safer for high-risk patients with bladder tumors, such as those with implanted pacemakers or pregnant women. In this meta-analysis, we analyzed the results of nine RCTs, which included 1193 patients being affected by bladder tumors, thereby comparing the outcomes between individuals treated with bipolar TURBT to those treated with monopolar TURBT.
Our analysis showed that bipolar TURBT is more effective and safer, which may be associated with reduced thermal damage, shorter hospital stay, and less bladder perforation. No significant differences in catheterization time, operative time, detrusor muscle sampling rate, obturator nerve reflex, TUR syndrome, hemoglobin drop, and transfusion were found between the two groups. This result is not exactly consistent with other data from previous meta-analyses., Cui et al. revealed that there were no statistically significant differences between bipolar TURBT and monopolar TURBT for bladder perforation and thermal cautery. Zhao et al. reported that there were fewer complications such as bladder perforation and thermal damage. The analysis of thermal damage was included only in two studies. Both meta-analyses rely on a large number of patients, but a major limitation of these studies was the fact that they included a few RCTs. As they were largely based on retrospective studies, which may be more susceptible to confounding biases, therefore the confidence of these findings is low. In contrast to previously published meta-analyses, this analysis included nine relevant RCTs, thereby creating a higher confidence level in its results.
The most common complication during TURB is bleeding. Although both meta-analyses reported a statistical difference in hemoglobin decrease using monopolar TURBT, blood loss requiring intervention did not differ. There was no difference in hemoglobin drop and transfusion rate between the bipolar and monopolar TURBT in our study. Nowadays, to the surgeon bleeding is not a severe risk factor during TURBT. However, bloodless resection can provide a clearer field and help reduce the incidence of complications. TUR syndrome after TURBT is rarely reported. Only three cases of TUR syndrome were reported in two RCTs included in our meta-analysis, which were all in patients treated by monopolar TURB. No patients undergoing bipolar TURB had TUR syndrome. No statistically significant differences between the groups were observed for the rarity of this complication. Monopolar TURB is performed using a larger loop than bipolar TURB and can take less time. Alternatively, tissues often adhere to the resection loop during monopolar TURB, this could lead to the necessity of manual removal during the procedure, thereby prolonging operative time. Considering the two side effects, there may be no difference in operative time. Our results are in accordance with the study, which reported no difference between the two groups for operative time. The differences between both procedures in obturator reflex is an area of strong debate and confusion. Some reports reported an incidence of ~1%, while other reports described the occurrence of obturator reflex in nearly half of the patients. Both trials denied a statistical difference between both techniques. Zhao et al. reported that the bipolar TURBT group was associated with fewer cases of obturator nerve reflex. Our meta-analysis revealed no significant difference in terms of obturator nerve reflex between the bipolar and monopolar TURBT. The different types of anesthesia employed and the tumor site in some studies may explain the statistical heterogeneity in pooled obturator nerve reflex data. Bladder perforation is a potential severe complication in TURBT, which not only has a high risk of extravesical tumor seeding, but also increases the risk of bleeding. In our pooled analysis, the incidence rate of bladder perforation was significantly lower in bipolar TURBT. Obturator jerk or deep resection, which results in violent adduction of the leg during resection may cause injury or even perforation of the bladder wall.
The pathological specimen should be suitable for elegant pathological assessment. There were no statistically significant differences between bipolar and monopolar TURBT for detrusor muscle sampling rate. However, in our study, the incidence of thermal damage, which causes histopathological artifacts was significantly lower in the bipolar arm. Cautery artifacts often affect adequate pathological assessment of tissue samples. This depends on the heat generated during resection, duration of loop contact with tissue, loop size, and tissue composition. Decreased tissue charring and a lower temperature during bipolar resection could have contributing factors. Our pooled analysis for catheterization time revealed no statistical differences between the two groups. The lower occurrence rate of complications in bipolar TURBT can help shorten the postoperative recovery period. Our meta-analysis reports that the length of hospital stay was significantly shorter in bipolar TURBT. The policy of hospital stay is variable from one institute to another and from a country to another, so the procedures of TURBT were not performed in the same way, as this might be influenced by differences in reimbursement systems. Two of all included trials reported the recurrence rate, with a follow-up period of 1- and 2-year, respectively. There was no impact on the recurrence rate no matter the type of energy that was utilized. Other studies have also reported that there was no impact on the recurrence rate no matter what type of energy was utilized.
This study has several limitations; first, the search was restricted to just studies published in English. We also excluded some reports of bladder tumor management that utilizes the bipolar energy technique because it is to be performed by tumor plasma vaporization rather than resection. Second, some variables differ between the two groups, such as the experience of the operating surgeon, efficacy of perioperative care, and tumor size or location. Furthermore, urologists might prefer one of both resection techniques, potentially introducing variability in the study outcomes. Third, only two of the studies reported data of the follow-up and duration of the follow-up was too short to depict a difference in recurrence-free survival. In addition, large-scale prospective RCTs with long-term patient follow-up are essential to confirm these findings.
| > Conclusion|| |
This meta-analysis suggests that the use of bipolar technology, which is associated with less bladder perforation and shorter hospital stay in TURBT is safer and more effective when compared to monopolar TURBT. Moreover, after bipolar TURBT a better specimen with significantly lower thermal artifacts could be made available for pathological assessment. Compared to the two procedures, there was no significant difference in terms of blood loss requiring transfusion, hemoglobin drop, detrusor muscle sampling rates, obturator nerve reflex, operative time, and catheterization time. No sufficient evidence can prove that bipolar TURBT improves the 2-year recurrence-free survival rate. Therefore, more large-scale, multicenter, randomized controlled studies are needed to judge the impact of bipolar resection on recurrence-free survival rate.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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