Evans 1973.

Methods	Study: prospective, randomised. Allocation: coin. Blinding: no.
Participants	97 patients: 48 P / 49 C.
Interventions	Herniorrhaphy ATB: cefaloridine 1 gr IM. MA: induction and two dosis postoperatives. Control: no treatment.
Outcomes	IP= 1;IC= 2
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Toss of a coin
Allocation concealment (selection bias)	High risk	Quote: "To avoid bias the details were entered not in the patients' case notes but on punch cards which were kept separately and analysed manually." Comment: Probably not done.
Blinding (performance bias and detection bias) All outcomes	High risk	Concealment not mentioned. Comment: Probably not.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not mentioned. Comment: Probably not.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not mentioned. Comment: Probably not.