Objective To investigate the effect of the endoscopic surveillance system in irrigating fluid absorption and bleeding during transurethral resection of the prostate.Methods In vitro trials,we simulated the fluid absorption and bleeding in the operation by using self-developed endoscopic surveillance system from January 2013 to June 2013.Continuous irrigation of 5 ％ mannitol solution,we extracted 5 times irrigating fluid (each time 100 ml and a total of 500 ml) in the process of irrigation and recorded absorption measurements of every time extraction rinses.At the same time,we dripped human whole blood 5 times(each time 5 ml and a total of 25 ml) in the process of irrigation and recorded the bleeding measurements.The above process was repeated three times to detect the accuracy and consistency of the endoscopic surveillance system.In clinical trials,50 cases of BPH were monitored in surgery and the biochemical index,hemodynamics,irrigating fluid absorption and bleeding were compared from October 2016 to April 2017.The included criteria contained as follow:the age of patients should be more than 50 years.The transabdominal ultrasound showed that the volume of prostate should be more than 60 ml.The maximal uroflowmetry should be less than 15ml/s.The IPSS scores should be more than 8.Based on the operative time,two groups (＜60 min and ≥ 60 min) were classified.Results We developed the endoscopic surveillance system which is original in the world.In vitro trials,the average irrigating fluid were (100.60 ± 2.07) ml,(201.00±3.39) ml,(302.00±4.67) ml,(403.60±4.39) ml and (502.40 ±7.57) ml;and the average bleeding were (5.06 ± 0.11) ml,(10.10 ± 0.16) ml,(15.04 ± 0.15) ml,(20.06 ± 0.11) ml and (25.10 ± 0.16) ml.No significant difference was observed in all groups (P ＞ 0.05).In clinical trials,we compared some preoperative and postoperative indexes.The average blood oxygen saturation were (94.46 ± 2.49) ％ and (92.39 ± 2.77) ％ (P ＜ 0.01),the average Serum sodium ion concentration were (141.05 ± 2.52) mmol/L and (138.06 ± 4.27) mmol/L(P ＜ 0.01),the average HGB were (143.50 ± 13.43) g/L and (137.04 ± 14.25) g/L(P ＜ 0.01).The average HCT were (42.05 ± 4.09) ％ and (137.04 ± 14.25) ％ (P ＜ 0.01).The average HR were (77.9 ± 7.6) beats per minute and (77.93 ± 6.93) beats per minute (P＞0.05).The MAP were (90.32 ± 9.75) mmHg and (91.07±8.96)mmHg(P＞0.05).The average serum potassium ion concentration were (4.13 ± 0.53) mmol/L and (4.09 ± 0.37) mmol/L (P ＞ 0.05).The average irrigating fluid absorption of the group less than 60 minutes and the group equal or more than 60 minutes were (401.83 ± 279.23) ml and (885.25 ± 367.68) ml (P ＜ 0.01).The average blood loss were (64.10 ±47.47) ml and (158.40 ± 65.22) ml(P ＜0.01).The preoperative and postoperative hemodynamic,blood biochemical and hematology showed difference in our trials.Irrigating fluid absorption and blood loss were positively associated with operation time.Conclusions The endoscopic surveillance system was safety and accuracy.It can offer real-time monitoring data and alarm mechanism for the surgeons that possibly improve operation safety.