Methods	RCT; 3 parallel groups.
	Unit of randomization: individual.
Participants	Dates of data collection: not reported.
	Setting: Tripler Army Medical Center, Honolulu, Hawaii, US.
	Inclusion criteria: all women undergoing CS (19/60 women had ruptured membranes > 6 hours; 40/60 were in active labor)
	Exclusion: known infection, currently on antibiotics, allergic to penicillin or cephalosporin
Interventions	Cefamandole 2 g in 800 ml normal saline irrigation (N = 30) vs irrigation with 800 ml normal saline (N = 30). Non-irrigation control group (N = 30) not included in analysis
Outcomes	Endomyometritis (fever, unusual uterine and parametrial tenderness without evidence of other source of infection); maternal length of stay
Notes	Length ofhospital stay for the control group included results from both the no irrigation group and the placebo irrigation group (5.37 days vs 4.53 for treatment group)
	Class of antibiotic: second generation cephalosporin.
	Subgroups: both elective and non-elective CS, data cannot be separated; after cord clamping.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Yes	Randomly allocated using table of random numbers.
Allocation concealment?	Yes	Randomly allocated by hospital pharmacy.
Blinding?	Yes	Double-blind, placebo-controlled.
All outcomes		Vitamin solution added to make placebo visually identical; physicians and patients blinded to treatment
Incomplete outcome data addressed?	Yes	No losses were reported.
All outcomes		No participants excluded.
		ITT analysis.
Free of selective reporting?	Unclear	Insufficient information to judge.
Free of other bias?	Unclear	The 3 groups were comparable regarding age, parity, weight and socioeconomic background. Insufficient information overall
Overall low risk of bias?	Yes	Mostly low risk of bias.