Abstract: Objective：To observe the change of blood sodium level and other biochemical indexes during class-4 hysteroscopic surgery after intravenous injection of 20 mg Frusemide when the uterine distention fluid is more than 5 000 mL, so that to find out when Frusemide should be used. Methods：Totally 61 patients with class-4 hysteroscopic surgery whose uterine distention fluid exceeded 5 000 mL were randomly divided into the experimental group（30 patients） and the control group（31 patients）. 20 mg Frusemide were injected intravenously for patients in the experimental group, while the control group had no special treatment. Their blood potassium, sodium and serum glucose after 1 h, 4 h, 8 h and the incidence rates of hyponatremia after surgery were compared, retrospectively. Results：The comparison of electrolyte level, glucose level and plasma osmotic pressure in two groups were of no statistical significance（P＞0.05）. The level of potassium, sodium and plasma osmotic pressure after 1 h and 4 h of the operation were significantly lower than that  before operation. There was a significant higher blood glucose level after operation than that before operation（P＞0.05）. Compared with the control group, sodium level in the experimental group was significant higher after 1 h of the operation （P＜0.05）, there was no difference in the blood potassium, glucose level and plasma osmotic pressure（P＞0.05）. The incidence of dilutional hyponatremia in the experimental group and the control group were 13.3％ and 19.4% respectively, which was with no significantly difference（P＞0.05）. Conclusions：Frusemide can be used when the uterine distention fluid is more than 5 000 mL during hysteroscopic electrosurgery, which is benefit for keeping the balance of blood electrolytes, avoiding the complication of overload and improving the safty of class-4 hysteroscopic surgery.

Key words: Hysteroscopy, Hyponatremia, Water-electrolyte imbalance, Furosemide