Lewis 1990.

Methods	RCT. Individual women. Study in 2 parts. Study 1: compared a penicillin vs placebo (so not included in this review). Study 2: compared a cephalosporin vs a penicillin.
Participants	Inclusion criteria Women having CS. N = 396, 9 excluded as charts not available, leaving 383 for analysis. Exclusion criteria Women who had antibiotics within 2 weeks of CS and those allergic to penicillin.
Interventions	Intervention: cephalosporin (B2). Cefoxitin. 2 g in 1.5 L, by irrigation. N = 186. Comparison: penicillin (A3). Ticarcillin. 5 g in 1.2 L, by irrigation. N = 197.
Outcomes	Endometritis; wound infection (criteria not specified): UTI (criteria not specified): sepsis.
Notes	Setting: Louisiana State University Hospital, US. Subgroups Both elective and non‐elective CS. Data reported separately but randomisation not stratified. After cord clamping. Irrigation/lavage. Single lavage dose but Comparisons: 1 (subgroup 1): 2; 3; 4; 7. No information about funding source of study.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“...random double‐blind fashion...”.
Allocation concealment (selection bias)	Unclear risk	“...random double‐blind fashion...”.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind study.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Although a double‐blind study, it is unclear whether the outcome assessors might have not know allocation.
Incomplete outcome data (attrition bias) All outcomes	Low risk	396 women were reported to be included with 383 providing data, 186 in cephalosporin group and 197 in penicillin group (loss of 13/396 = 3.3%).
Selective reporting (reporting bias)	Unclear risk	We did not assess trial protocol.
Other bias	Unclear risk	Baseline characteristics were similar for age; gestation; gravidity; parity; length of labour. However, other potential biases were unclear. No information about funding source of study.