This study is designed to examine the incidence of postoperative nausea and vomiting during 24 hours after elective laparoscopic cholecystectomy in patients receiving preoperative intravenous fluid loading (group F), ondansetron (group O) and receiving neither fluid nor ondansetron or control group (group C).

This study is a prospective randomized control trial. It is designed to examine the incidence of postoperative nausea and vomiting during 24 hours after elective laparoscopic cholecystectomy in patients receiving preoperative intravenous fluid loading (group F), ondansetron (group O) and receiving neither fluid nor ondansetron or control group (group C). This study is hypothesized that the incidence of PONV in patients receiving preoperative intravenous fluid loading (group F) and patients receiving ondansetron (group O) will be similarly reduced from the control group (receiving neither fluid nor ondansetron).

Inclusion Criteria:

• patients with aged 18 to 70 years with an ASA physical status 1-3

Exclusion Criteria including patients

• with pregnant or breast-feeding patients
• having history of taking antiemetic drugs within 24 hours before surgery
• with hypersensitivity or allergy to ondansetron
• with CKD stage 4, 5
• with congestive heart failure, LVEF <40
• with cirrhosis child c
• refusal or cannot communicate or understand the purpose of this study