BackgroundBipolar and monopolar transurethral resection of prostate (TURP) are both widely used for surgical treatment of benign prostatic hyperplasia. Systemic absorption of irrigation fluids during TURP operations leads to variations in blood chemistry. The aim of this prospective clinical study was to compare two different surgical techniques and the systemic effects of irrigation solutions (5 % mannitol vs. 0.9 % sodium chloride) under standardized anesthesia care.MethodsFifty-two patients who were scheduled for elective TURP were enrolled in the study. Patients were divided into two groups; the group M; 5 % mannitol was used for irrigation and the group B; 0.9 % sodium chloride was used for irrigation. Spinal anesthesia was performed to all patients. The patients’ demographics, prostate volumes, hemodynamic parameters, volumes of irrigation, and IV fluids were recorded. Serum electrolytes (Na+, K+) and hemoglobin (Hb) were analyzed in blood samples taken before the operation (control), at the 45th min of the operation (1st measurement), and 1 h after the end of the surgery (2nd measurement) and recorded.ResultsThe Na+ value of group M was significantly lower in both the 1st and 2nd measurements compared with the control value (p < 0.001 and p < 0.001). Na+ values of group M were also significantly lower than group B in both the 1st and 2nd measurements (p < 0.001 and p < 0.001). The change in Na+ levels was found to be statistically significant (p < 0.001) in group M, whereas the intergroup changes were not statistically significant in group B.ConclusionOur results demonstrated that bipolar resection coupled with 0.9 % sodium chloride has minimal effects on serum sodium levels compared with monopolar resection. Clinicaltrials.gov identifier NCT02681471