Chongsomchai 2002.

Methods	Design: randomised double‐blinded No. eligible: 330 No. randomised: 330 No. analysed: 321 Drop‐outs/withdrawals: 9 did not undergo hysterectomy as planned (3 in cefazolin group, 4 in ampicillin group, 2 in placebo group) Years of recruitment: 1997 to 1999 Setting: 2 regional hospitals in Thailand
Participants	Inclusion criteria: scheduled for elective total abdominal hysterectomy Exclusion criteria: preoperative fever or infection, allergic to ampicillin or cefazolin, had received antibiotics within 48 hours of surgery, emergency cases, pregnancy‐related cases Age: mean 43 years Type of hysterectomy: abdominal
Interventions	Treatment 1: 1 gram ampicillin (penicillin) Treatment 2: 1 gram cefazolin (first‐generation cephalosporin) Control: placebo Route: IV Single/multiple doses: single Timing of doses: 30 minutes before surgery
Outcomes	Postoperative infection, early and late Abdominal wound infection Urinary tract infection Pelvic infection Adverse effects (narrative data only) Other serious infection Postoperative fever Asymptomatic infection Follow‐up: 4 weeks
Funding	National Research Council, Thailand
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Computer‐generated randomization"
Allocation concealment (selection bias)	Low risk	"Opaque sealed envelopes" ‐ probably done
Blinding (performance bias and detection bias) All outcomes	Low risk	"Patients, their gynaecologists, all investigators and evaluators were blinded to the random allocation throughout the study"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Proportions of withdrawals/losses to follow‐up similar in treatment groups and < 10% in each group
Selective reporting (reporting bias)	Low risk	All reported outcomes were prespecified in the methods section
Other bias	Low risk	Baseline demographic characteristics similar between treatment groups