| Abstract: | Mechanical strength of the left colon with anastomosis and the intact transverse colon was studied by the bursting strength technic from four to fourteen days after standardized left colon resection in the rat. Two different single layer inverting suture technics were used, continuous suture and interrupted sutures. Bursting strength was tested by determinations of both bursting pressure and bursting wall tension, both of which provided the same information concerning mechanical strength of the colon. The bursting strength test measures the anastomotic strength only during the early stages of healing, since more than 90 per cent of the left colon segments ruptured outside the anastomosis as early as day 7. The two different suture technics resulted in the same bursting strength of the left colon segment with anastomosis. Both types of anastomoses showed a moderate narrowing at the anastomotic line upon inflation. This was due to the fact that the anastomosis constituted a relatively firm fibrotic ring from day 7, and both types of anastomoses had an equal inner diameter at that time. By supporting the colonic wall above and below the anastomosis, it could be calculated that the anastomosis on day 7 withstood at least 50 per cent higher circular wall tension than the surrounding colonic wall.There was no correlation between collagen concentration of the colonic wall and bursting strength of the colon either in unoperated controls or after resection and anastomosis. When interrupted sutures were used for anastomosis of the left colon, bursting strength of the intact transverse colon was significantly higher on day 7 than when continuous suture was used. It actually exceeded that of the transverse colon in unoperated controls by almost 50 per cent on the seventh postoperative day, although the collagen concentration in the transverse colon was within normal range. This finding indicated changes in the proximal colonic wall after left colon resection, which are probably related to changes in the structure or arrangement of collagen. |
