A prospective study was performed to evaluate the preventive effect of intravenous (IV) ondansetron on postoperative nausea and vomiting (PONV) due to epidural morphine for postoperative pain control after major abdominal surgery.

One hundred patients undergoing elective major abdominal surgery were randomly devided into two groups, group O (n = 50) receiving IV ondansetron and group C (n = 50) receiving IV saline. After bolus epidural morphine were injected to all patients thirty minutes before the end of surgery, group O received ondansetron 8 mg and group C received normal saline intravenously. Incidence and severity of nausea, episodes of vomiting, patient's satisfaction, side effects such as pruritus, headache, dizziness related to epidural morphine were checked at 6, 24 hours after operation.

The incidence and severity of nausea were significantly decreased in group O than group C during the first 24 hours after surgery. There were no significant differences in postoperative pain scores and patient's satisfaction between groups. The patients who didn't experienced PONV were significantly more satisfied than those who experienced PONV after surgery.

Ondansetron decrease the incidence and severity of nausea in patients receiving epidural morphine for postoperative pain control after major abdominal surgery.