Effects of Local Ischemia and Bacterial Flora on Healing of Experimental Colonic Anastomoses

Abstract

In the present study the effects of local bowel perfusion on anastomotic healing of experimental colonic anastomoses were evaluated in 54 female chinchilla rabbits. Local ischemia was induced by devascularization of the sigmoid colon. Animals were randomly allocated to 4 operative groups. In the animals of group 1 a colo-colonic anastomosis was performed in an area graded as ischemia grade A (intact perfusion). Animals of group 2 received a colo-colonic anastomosis in the sigmoid colon segment, graded as ischemia grade B (marginal perfusion). Group 3 received pretreatment with neomycin and was otherwise treated like group 2. Animals of group 4 a colo-colonic anastomosis was performed in the ischemia grade-C region (total ischemia). The rate of anastomotic leakage was monitored by periodic double contrast enemas. The experiment was terminated on the 8th postoperative day, and microangiography to assess revascularization was performed followed by assessment of perianastomotic adhesions. The rate of anastomotic failure as well as the occurrence of anastomotic failure over time highly depended on the severity of ischemia. Bowel sterilization by neomycin significantly reduced the rate of anastomotic leakage. The development of perianastomotic adhesions correlated with the severity of ischemia. Microangiography suggested that revascularization originated in the perianastomotic adhesions.