Brownson 1992.

Methods	Stated that randomised, but no details provided about randomisation method.
Participants	Inclusion criteria: participants undergoing elective colorectal surgery. Exclusion criteria: no details. Diseases: colorectal cancer: 164/179; other: 14/179. Number of participants: 179. Age: no details. Location of study: Liverpool, UK.
Interventions	Group A ‐ MPB (n = 86); Group B ‐ no preparation (n = 93). Antibiotics: perioperative intravenous (no more details).
Outcomes	Wound infection: Group A = 5, Group B = 7. Intra‐abdominal sepsis: Group A = 8, Group B = 2. Anastomic leakage: Group A = 8/67*, Group B = 1/67*. *only participants in whom bowel continuity was restored.
Notes	Conference proceeding only ‐ never published as article, so results obtained from abstract. Attempt to contact the authors met with no success.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear