A Study of TAK-951 to Stop Adults Getting Nausea and Vomiting After Planned Surgery

The drug being tested in this study is called TAK-951. TAK-951 is being tested for prophylaxis for postoperative nausea and vomiting in high-risk participants. The study will enroll a maximum of 160 patients, to allow a sample size of up to approximately 100 participants who have received both doses of Double-blind study drug/matching placebo. Participants will be randomly assigned in a 1:1 ratio to either Treatment Group A or Treatment Group B which will remain undisclosed to the patient and study doctor during the study (unless there is an urgent medical need): * Treatment Group A: Just before surgery, participants will receive a placebo slowly through a vein (infusion). Just before the end of the surgery, they will receive TAK-951 as an injection under the skin. * Treatment Group B: Just before surgery, participants will receive ondansetron slowly through a vein (infusion). Just before the end of the surgery, they will receive a placebo as an injection under the skin. In this study, a placebo will look like TAK-951 but will not have any medicine in it. This trial will be conducted in the United States. The overall time to participate in the study from the time of surgery to completion is approximately 14 days. Participants will make multiple visits to the clinic and will be contacted by telephone after receiving their last dose of the drug for a follow-up assessment.