Ross 1984.

Methods	RCT; 2 parallel groups. Unit of randomization: individual.
Participants	Dates of data collection: not reported. Setting: Addenbrooke's Hospital, Cambridge, UK. Inclusion criteria: women undergoing emergency CS (in active labor with membrane rupture). N = 115. Exclusion criteria: pyrexia; antibiotic use within 2 weeks.
Interventions	Intervention: nitroimidazole: metronidazole 500 mg; N = 57. Comparison: placebo: placebo; N = 58. IV infusion at start of procedure; post‐operatively metronidazole or placebo suppository twice daily for 5 days.
Outcomes	Pyrexia (> 38oC twice 4 hrs apart after 1st 24 hrs); wound infection; endometritis (heavy, offensive lochia and pyrexia); UTI; antibiotic use (15/57 in treatment group vs 20/58 in control group).
Notes	1 woman in the control group developed a pelvic abscess. Length of admission not significantly different between the 2 groups (mean 7.4, SD 2.3 days). No adverse reactions occurred. Class of antibiotic: nitroimidazole (metronidazole). Subgroups: non‐elective CS; before cord clamping. Comparison of the 2 groups showed similar risk factors.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Randomized, sequential basis". Comment: insufficient description of sequence generation process.
Allocation concealment (selection bias)	Unclear risk	Quote: "Antibiotic ... was provided without access to the 'trial code". Comment: insufficient information to judge.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: no loss to follow‐up; no participant excluded. ITT analysis.
Selective reporting (reporting bias)	Unclear risk	Comment: insufficient information to judge.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: double‐blind, placebo‐controlled.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: insufficient information to judge.
Other bias	Low risk	Comment: no other sources of bias identified.