The impact of the menstrual cycle and ondansetron on postoperative nausea and vomiting

The incidence of postoperative nausea and vomiting was studied in a prospective group of 94 women of child-bearing age (18-42 years), undergoing unilateral elective thyroid surgery. In a subgroup of 47 examinees the postoperative nausea and vomiting episodes were analyzed according to the time of surgery within their menstrual cycle: the highest occurrence was observed in the periovulatory and premenstrual periods (65.5% vs. 27.8%, p < 0.02). In the formal part of this study, 25 patients randomly received ondansetron (8 mg intravenous [i.v.]): they had significantly less postoperative nausea and vomiting than their 22 placebo controls (4 ml saline i.v.): 16.0% vs. 45.5% (p < 0.04). It is concluded that elective surgery in young and middle-aged female patients is best avoided premenstrually and in the middle of their cycle. In these very periods, however, ondansetron effectively reduces the incidence and intensity of postoperative nausea and vomiting by about 70%.