RESUMO
BACKGROUND AND AIMS: To evaluate the effect of mechanical bowel preparation (MBP) on colonic resection and anastomosis. PATIENTS AND METHODS: Mongrel dogs were divided into two groups of 20 animals each. During the preoperative period (24 h) group A was not subjected to MBP, and group B was fasted and ingested 20 ml magnesium hydroxide plus 15 ml/kg 10% mannitol orally. All animals underwent segmental colectomy followed by end-to-end anastomosis. The survivors of both groups were reoperated upon on the 7th postoperative day. RESULTS: Mortality before reoperation was significantly higher in group A (45%) than in group B (10%; P<0.05). Upon reoperation on surviving animals the incidence of localized anastomotic leakage, leakage with peritonitis, and healed anastomoses was 72.72%, 9.09%, and 18.8% in group A, and 66.66%, 22.22%, and 11.11% in group B, respectively (P>0.05). Aerobic and anaerobic bacterial cultures showed similar growth in the two groups. CONCLUSION: We conclude that the omission of MBP increased the mortality due to early anastomotic leakage with peritonitis; MBP did not change the rate of localized anastomotic leakage, leakage with peritonitis, or intact anastomoses on the 7th day; no quantitative or qualitative differences were observed in the bacteria isolated from the two groups.