Objective: To estimate the incidence of excessive distension absorption in the patient went through hysteroscopic surgery distended with 5% mannitol solution, to evaluate the use of 5% mannitol solution for hysteroscopic surgical procedure specifically and to testify the safe threshold for distension absorption. Design: Retrospective. Setting: Academic medical center. Patients: 10693 patients went through inpatient hysteroscopic surgery distended with 5% mannitol solution using monopolar electrosurgical instrument from Jan. 2015 to Sep. 2020. Intervention(s): None. This study has been approved by the Ethics Committee of Sun Yat-sen Memorial Hospital. Measurements and Main Results: Fluid deficit more than 1000mL is defined as excessive distension absorption. Incidence of excessive distension absorption in all the inpatient hysteroscopic surgeries is 0.46% (49/10693). It is 2.57% (16/623) in transcervical resection of fibroid (TCRF), 2.36% (9/381) in retained products of conception (RPOC) removal, 1.20% (6/501) in hysteroscopic uterine septum resection (HSR), 0.53% (14/2621) in transcervical resections of adhesion (TCRA) while in the severe cases it was 2.34% (14/598), 0.48% (4/828) in transcervical resection of the endometrium (TCRE). Excessive distension absorption developed within ten minutes in two cases. Twelve of thirty nine patients with fluid deficit under 2500mL presented with clinical consequences related to circulation overload. Conclusion: Incidence of excessive distension absorption could be low generally however it would be five times higher in TCRP, RPOC removal and TCRA. Resection by needle electrode may contribute to the excessive distension absorption developed within short time. 30.77% of the patients could not tolerate the less than 2500mL distension absorption.