Tanner 1980.

Methods	Randomised controlled trial. Randomisation method not stated. Patient blinded. Unclear blinding of surgeon and outcome‐assessor.
Participants	111 eligible patients. 7 patients excluded. 104, 51 males and 53 females enrolled in the study. Age‐range 8‐71 Mean: Treatment group: 26 +/‐ 14 (s.d.), placebo group: 25 +/‐ 15 (s.d)
Interventions	Treatment group: Metronidazole 1 g suppositorium preoperatively. Placebo group: Glycerine supp preoperatively.
Outcomes	Wound infection (Presence of pus or a purulent exudate at the wound).
Notes	Drain treatment to all patients with perforated appendix.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear