Table 1. Inclusion and exclusion criteria for study subjects.

INCLUSION	EXCLUSION
Females aged 18–80 years	Declined to participate
Subjects parents and grandparents are of Chinese descent by self-report	Allergic to opioids
American Society of Anaesthesiologists (ASA) physical status I and II	Undergoing termination of pregnancy or laparoscopic surgery
Undergoing gynaecological day surgery at the Day Surgery Unit of KKWH
Intact cognition
Body mass index (BMI)<35
No history of emesis or anti-emetic usage for at least 2 days prior to entry into the study
Opioid-naïve
Non-smokers
Not pregnant
No history of migraine or motion sickness
No history of alcohol or drug abuse

Abbreviations: KKWH: KK Womens Hospital.