Hedican 1976.

Methods	Design: randomised double‐blinded No. eligible: not stated No. randomised: 70 No. analysed: 70 Drop‐outs/withdrawals: none Years of recruitment: 1971 to 1972 Setting: university gynaecology and obstetrics department, USA
Participants	Inclusion criteria: women having elective vaginal hysterectomy Exclusion criteria: preoperative infection, taking antibiotics, allergy to study drugs, elevated blood urea Age: not stated Type of hysterectomy: vaginal
Interventions	Treatment: cephaloridine (first‐generation cephalosporin) Control: placebo Route: IV, then IM Single/multiple doses: multiple Timing of doses: 1 gram IV at start of operation, 1 gram IM 5 hours postoperatively, 1 gram IM 12 hours postoperatively
Outcomes	Postoperative infection, early Pelvic infection
Funding	Lilly Company
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	State that "patients were numbered consecutively 1‐70 and randomly assigned..."; no additional details reported
Allocation concealment (selection bias)	Low risk	Appears to be remote allocation ‐ "patients were ... randomly assigned either the placebo or the study drug by the pharmacy"
Blinding (performance bias and detection bias) All outcomes	Unclear risk	"Following the completion of the study ... the code was broken"; no details on outcome assessment provided
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Appears that all participants were analysed
Selective reporting (reporting bias)	Unclear risk	Insufficient information to make a conclusive judgement
Other bias	Unclear risk	Insufficient information to make a conclusive judgement