Ledger 1973.

Methods	Design: randomised double‐blinded No. women eligible: 164 No. women randomised: 100 No. women analysed: 100 Drop‐outs/withdrawals: none Years of recruitment: 1970 to 1972 Setting: University of Michigan Medical Centre
Participants	Inclusion criteria: premenopausal women having vaginal hysterectomy Exclusion criteria: allergy to study drugs, high preoperative blood urea, already receiving prophylactic antibiotics, "vaginal approach was decided upon in the operating room" Age: mean 35 years Type of hysterectomy: vaginal
Interventions	Treatment: 1 gram cephaloridine (first‐generation cephalosporin) Control: placebo Route: not stated Single/multiple doses: multiple Timing of doses: first dose on call to operating room, second dose on return from recovery room, third dose at bedtime night of operation
Outcomes	Postoperative infection, early Urinary tract infection Pelvic infection Postoperative fever Need for therapeutic antibiotics Hospital length of stay Follow‐up: to hospital discharge *Also reports "other morbidity" ‐ no separate data for "other serious infections"
Funding	Eli Lilly Company
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random numbers table
Allocation concealment (selection bias)	Low risk	States that allocation was "assigned by the pharmacy service" ‐ probably remote allocation
Blinding (performance bias and detection bias) All outcomes	Low risk	States that "the code identifying placebo or active drug was broken only after the patient had been discharged and the clinical summary sheets...completed"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Reported no drop‐outs
Selective reporting (reporting bias)	Unclear risk	Insufficient information to make a conclusive judgement
Other bias	Low risk	Baseline demographic characteristics similar between treatment groups