Abouleish 1999.

Study characteristics
Methods	RCT
Participants	74 women 18‐40 years undergoing elective CS at term under spinal anaesthesia, ASA 1‐2, no significant maternal medical conditions.
Interventions	Intervention: 5‐HT3antagonist (Comparison 1) Ondansetron IV ‐ 4 mg. N = 36. Comparator: placebo Normal saline 2 mL. N = 38.
Outcomes	Nausea ‐ presence/absence and severity. Vomiting ‐ severity, frequency.
Notes	Setting: Texas, USA. The Middlesex Hospital, London, UK. Dates: not reported Funding source: funding was received from Glaxo‐Wellcome and NEI Vision Core Declaration of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated random number table.
Allocation concealment (selection bias)	Unclear risk	Syringes produced by pharmacy.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Described as "Double blind" but no other details provided
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Described as "Double blind" but no other details provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	8 participants withdrawn, 5 withdrew consent, 2 had an exclusion criteria (oesophageal reflux), 1 failed spinal converted to GA. Data not re‐included.
Selective reporting (reporting bias)	Unclear risk	We did not assess the trial protocol.
Other bias	Low risk	Mild increase in BP in the control group, not significant.