The effects of mechanical preparation and acidification of the colon on the healing of colonic anastomoses.

The results of clinical studies have suggested that inadequate preoperative mechanical preparation of the colon is a significant factor in the pathogenesis of disruption of colonic and colorectal anastomoses. A possible explanation for the adverse effect of poor mechanical preparation is that ammonia released from feces has a cytotoxic effect on the healing anastomosis. It has been suggested that acidification of the colonic lumen prevents the release of fecal ammonia and protects the anastomoses. The effects of mechanical preparation of the colon and colonic acidification were studied in anastomoses in the left colon of rats. Colonic acidification was produced by the oral administration of a synthetic disaccharide lactulose solution. Mechanical preparation resulted in a significant increase in the bursting wall tension in anastomoses on the seventh postoperative day. The oral administration of lactulose resulted in a reduction in the colonic mucosal pH, but this was not accompanied by improved healing of anastomoses, as judged by measurements of colonic bursting pressure, bursting wall tension and total challagen content. Mechanical preparation of the colon is an important factor in the safety of colonic anastomosis. However, the results do not suggest that acidification of the colonic lumen significantly improves the quality of colonic healing.