Blood flow in colon anastomotic stricture formation

PURPOSE: The influence of both blood flow and anastomotic technique on the development of anastomotic stricture formation was studied using a dog model. METHODS: Fifty-three dogs underwent distal colocolonic anastomosis with either an EEA^TM (U. S. Surgical Corp., Norwalk, CT) circular stapler or a Czerny-Lembert two-layered, handsewn anastomosis. Blood flow was measured by Laser Doppler Velocimetry using the Laserflo BPM^{2 TM} (Vasamedics Inc., St. Paul, MN). The animals were separated into three blood flow groups: greater than or equal to 62.5 percent of normal blood flow, between 37.5 percent and 62.5 percent of normal blood flow, and less than or equal to 37.5 percent of normal blood flow. Each blood flow group had an anastomosis performed by either stapling or by hand sewing techniques. At six weeks, the anastomoses were opened longitudinally and fixed to determine the anastomotic index (AI). AI is defined as two times the anastomotic circumference over the proximal circumference plus the distal circumference. Blood flow groups and anastomotic technique groups were compared with an interaction variable for the outcome, AI using a two-way analysis of variance. RESULTS: The AI of the stapled anastomoses was found to be significantly higher than handsewn anastomoses (P<0.006). There was no difference in AI between different blood flow groups and no correlation of observed histologic findings with AI. CONCLUSION: Clinically relevant ischemia does not directly influence stricture formation in either handsewn or stapled distal colonic anastomoses.