Olanzapine for the Prevention of Postoperative Nausea and Vomiting

Inclusion Criteria: * ASA I and II patients * undergoing ambulatory laparoscopic gynecologic surgery with general anesthesia * patients have at least two of the four Apfel risk factors for PONV2 * Lack of history of psychiatric and psychotic illnesses. Exclusion Criteria: * ASA III and ≥ IV patients * Psychological diseases * History of chemotherapy * have a pre-existing vestibular disorder or history of dizziness or preexisting nausea or vomiting in the 24 h before surgery, or were being treated with regular antiemetic therapy including systemic corticosteroids.