Anastomotic healing in the rat colon: comparison between a radiological method, breaking strength and bursting pressure

Abstract

Background and aims: While mechanical parameters (breaking strength, bursting pressure) are used to measure colonic anastomotic healing, reported values are inconsistent. This study developed a novel approach to study colonic anastomotic repair and compared it with mechanical methods. Methods and materials: We created standardized four- and eight-suture colonic anastomoses and performed contrast enemas in rats. Results: All eight-suture anastomoses were tight at completion. In contrast, all four-suture anastomoses leaked immediately after the operation, but the integrity increased progressively, and at 12 h all were closed. No changes in breaking strength were observed up to 3 days postoperatively, in contrast to anastomotic bursting pressure which increased progressively over the same period. Integrity and bursting pressure increased in parallel to the anastomotic content of myeloperoxidase (MPO), indicating that neutrophil infiltration is not detrimental in normal healing. Moreover, local irradiation, which enhanced MPO activity, did not increase leakage, suggesting that neutrophil accumulation per se has no effect on the integrity of colonic anastomosis. In addition, administration of 5-fluorouracil, which decreased anastomotic MPO levels, increased anastomotic leakage. Conclusion: We present a novel approach to study anastomotic healing using radiological examination. While bursting pressure appears to be suitable for measuring early anastomotic healing in the colon, we demonstrate that breaking strength is not sufficiently sensitive to be used in examination of early healing. Moreover, our data suggest that the acute inflammatory response and associated neutrophil recruitment in the anastomosis does not negatively affect healing in the rat colon.