EFFECT OF IRRADIATION ON HEALING OF NEWLY MADE COLONIC ANASTOMOSES INTHE RAT

Purpose: Short-term effects of radiotherapy on the healing process of newly made colonic anastomoses are investigated by measuring the anast omotic strength in a rat model. Methods and Materials: Four groups of Wistar rats were used. In all groups, rats underwent a 1 cm sigmoid re section with end-to-end anastomosis. Group I served as a control group . In group II the anastomosis was irradiated after closure of the abdo minal wall with a single dose of 20 Gy of 250 kV x rays. Group III was irradiated with a single dose of 20 Gy while the abdominal wall was n ot closed, and the surrounding tissues were carefully covered by a lea d plate, simulating intra-operative radiotherapy. Group IV was treated as group III, but a larger dose of 25 Gy was applied. Animals were sa crificed 3 or 7 days after the operation. General condition of the rat s was determined by observation, weight loss, serum protein and albumi n at sacrifice. Anastomotic healing was evaluated by inspection, burst ing pressure, hydroxyproline and protein contents of the anastomotic s egment. Results: Direct postoperative externally irradiated rats (grou p II) showed a marked weight loss, hypoproteinaemia and hypo-albuminae mia because of involvement of small bowel in the irradiated volume. Wi th respect to anastomotic healing there were no significant difference s between control and irradiated groups.Conclusion: These data suggest that the application of a single dose of irradiation (20 and 25 Gy) o n colonic anastomoses given in a direct postoperative or intraoperativ e model has no measurable side effect on the early healing of newly ma de colonic anastomoses. Direct postoperative external irradiation resu lts in unwanted side effects in the adjacent bowel.