Safety and Efficacy of Bipolar vs Monopolar Transurethral Resection of Bladder Tumor-A Randomized Controlled Trial

All patients suspected to have bladder cancer were subjected to imaging or cystoscopy and with confirmation of the diagnosis; they were randomized into two arms of TURBT. Spinal anesthesia was used in all cases.

To overcome the potential confounding effect on our primary end point, obturator jerk, nerve block was not used.

Cystoscopy was done first and the findings were noted before proceeding to TURBT.

Monopolar resection was done using 1.5% Glycine solution at 110 watt cutting, and 70 watt coagulation power (Covidien Valley-lab Force Fx TM) with Karl Storz 26f resectoscope and loop (8mm width and 5mm depth) with 300 telescope. Bipolar resection was done with 0.9% Normal Saline with digital impedence dependent cutting (power range 150-250 watt) and 80 watt coagulation power (Bowa Arc 400) with Karl Storz 26f resectoscope and loop (6mm width and 5mm depth) with 300 telescope.

Tumors were resected in block from periphery to center with the stalk resected last. An additional sample of deep muscle was obtained from the tumor base and sent for histopathological examination in different containers. All study variables were recorded in Per forma during the operation and in post operative period. Hemoglobin and sodium level was determined in immediate post operative period.

Postoperative irrigation was done with normal saline in both the resection groups and continued till the urine was clear. The catheter was removed after 48 hours in uncomplicated cases and patients were discharged. Patients were followed up in Out Patient Department at 2 weeks with the histopathological report for or when necessary.

Study outcome:

The incidence of obturator jerk, bladder perforation, resection time, decrease in hemoglobin and serum sodium, clot retention, need for blood transfusion, need for recoagulation and TUR syndrome were recorded for the cases in both arms. All resected specimen were evaluated by pathologist for quality by determining the presence of deep muscle in the sample and comparing the degree of cautery artifact. Severe artifact was defined as more than 50% cautery artifact in most chips.

Statistical Analysis:

Sample size (n) was calculated using 80% power and a 95% significance level for obturator jerk, assuming a 30% incidence for the monopolar system and a 5% incidence for the bipolar system. These values were arrived at after a comprehensive literature review. The sample size was determined with the formula n= K {P1(1-P1) x P2(1-P2)}/ )P1-P2)2, Where:

N= sample size P1= prevalence of obturator jerk in Monopolar TURBT P2= prevalence of obturator jerk in Bipolar TURBT K= constant (7.9 for 80% power of study and 0.05 level of significance)

A sample size of 33 in each arm was calculated using above formula. Estimating a drop out of 10%, we decided to include at least 37 patients in each arm. A computer generated random number was used to allocate eligible patients in to monopolar or bipolar resection arm. Data analysis was done using Statistical Package for Social Sciences (SPSS) version 21. Significance was determined using the independent sample t-test for quantitative variables and the chi-square test for qualitative data. P value of <0.05 was considered statistically significant.