Randomized clinical trial of mechanical bowel preparation versus no preparation before elective left-sided colorectal surgery

Background: Mechanical bowel preparation (MBP) is performed routinely before colorectal surgery to reduce the risk of postoperative infectious complications. The aim of this randomized clinical trial was to compare the outcome of patients who underwent elective left-sided colorectal surgery with or without MBP. Methods: Patients scheduled for elective left-sided colorectal resection with primary anastomosis were randomized to preoperative MBP (3 litres of polyethylene glycol) (group 1) or surgery without MBP (group 2). Postoperative abdominal infectious complications and extra-abdominal morbidity were recorded prospectively. Results: One hundred and fifty-three patients were included in the study, 78 in group 1 and 75 in group 2. Demographic, clinical and treatment characteristics did not differ significantly between the two groups. The overall rate of abdominal infectious complications (anastomotic leak, intra-abdominal abscess, peritonitis and wound infection) was 22 per cent in group 1 and 8 per cent in group 2 (P = 0(.)028). Anastomotic leak occurred in five patients (6 per cent) in group 1 and one (1 per cent) in group 2 (P = 0(.)021). Extra-abdominal morbidity rates were 24 and 11 per cent respectively (P = 0(.)034). Hospital stay was longer for patients who had MBP (mean(s.d.) 14(.)9(13(.)1) versus 9(.)9(3(.)8) days; P = 0(.)024).