Bates 1980.

Methods	Controlled clinical trial. Random allocation by the admittiong house surgeon. No blinding of the patient. Adequate blinding of surgeon and unclear blinding of outcome assesor.
Participants	200 eligible patients. 30 excluded after randomisation. 170, 90 males and 80 females enrolled in study. Age‐range: 0‐90
Interventions	Treatment group: 1 g metronidazole supp 1 hour preoperatively and 1 g supp or orally 8 hourly postoperatively for 7 days. children below 12 received half dose. Placebo group: No treatment
Outcomes	Woundinfection (A frank discharge of pus) Lenght of stay in hospital
Notes	No drain treatment
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	High risk	C ‐ Inadequate