Fibrosis of experimental colonic anastomosis in dogs after EEA stapling or suturing

Two out of five patients with a colonic anastomosis stapled with the EEA device, under protection of a diverting colostomy, developed stenosis requiring reoperation. Therefore, a canine experiment was conducted in order to compare the degree of fibrosis in a sutured with that in a stapled anastomosis. A colonic loop excluded from the fecal stream was transsected twice. One anastomosis was done by sutures, the other by an EEA stapling device. The amount of fibrous tissue between the circular muscle layer and the lamina muscularis mucosae was measured on strips of 2-mm length. Immediately after surgery, the submucosal edema was similar in both anastomoses. Marked fibrous thickening of stapled anastomoses developed after two to six months. In contrast, sutured anastomoses elicited very little fibrous thickening of the lamina submucosa. This difference in fibrosis could not be demonstrated following use of the stapling device alone, i.e., without staples. The fibrous thickening, measured in a stapled anastomosis diverted from the fecal stream, exceeds that seen in a sutured anastomosis and may result in stenosis. Therefore, it is suggested that an anastomosis, protected by a diverting colostomy, should be sutured.