BACKGROUND: Postoperative nausea and vomiting remain a common problem following gynecologic surgery. This study was designed to compare antiemetic effects and to establish optimal doses for dexamethasone and ondansetron for the prevention of postoperative nausea and vomiting (PONV) during intravenous patient-controlled analgesia after gynecologic surgery.

METHODS: One hundred and fifty ASA 1-2 patients undergoing elective gynecologic surgery were included. Patients were randomly divided into six groups and received a placebo (group C), dexamethasone 4 mg (group D4), dexamethasone 8 mg (group D8), ondansetron 4 mg (group O4), ondansetron 8 mg (group O8) or dexamethasone 4 mg plus ondansetron 4 mg (group D4O4) after induction. Postoperatively, nausea, vomiting, VAS pain score, headache and itching were recorded in the recovery room (2 h after operation) and in the hospitalization area (12, 24 and 48 h after operation).

RESULTS: Group C showed a significantly higher incidence of nausea (56%) and vomiting (32%) than group D4 (nausea: 20%, vomiting: 4%), D8 (nausea: 20%, vomiting: 4%), O4 (nausea: 12%, vomiting: 4%), O8 (nausea: 12%, vomiting: 0%) and D4O4 (nausea: 20%, vomiting: 4%). No differences in the incidence of nausea and vomiting were observed between groups D4, D8, O4, O8 and D4O4. Pain score, total analgesic consumption, duration, and side effects were similar in the groups.

CONCLUSIONS: Dexamethasone 4 mg, dexamethasone 8 mg, ondansetron 4 mg, ondansetron 8 mg, and dexamethasone 4 mg plus ondansetron 4 mg were found to be equally effective at preventing PONV following gynecological surgery. Dexamethasone was as effective as ondansetron for the prevention of PONV after gynecologic surgery.