BACKGROUND: The use of mechanical bowel preparation is much debated.METHODS: We evaluated the effects of polyethylene glycol (PEG), with or without a single dose of 3.0 mmol butyrate (BUT), on the bursting pressure (BP) of an intact colon segment and a colon anastomosis in rats. Also, histopathologic damage was studied.RESULTS: In rats without colectomy, the mean BP was 159.2 mmHg (SD=18.9) after PEG treatment and 116.7 mmHg (SD=27.5) in controls (p=0.001). In rats with colectomy, the mean BP was 90.4 mmHg (SD=45.9) in the PEG group, 108.0 mmHg (SD=31.9) in the BUT group, and 102.7 mmHg (SD=44.7) in controls (p=0.44). No significant differences in histopathologic scores were observed between rats treated with PEG and controls.CONCLUSIONS: PEG does not interfere with anastomotic healing in rats as measured by BP. No benefit of a single dose of butyrate was observed.