Improvement of colonic healing by preoperative rectal irrigation with short-chain fatty acids in rats given radiotherapy

BACKGROUND: We investigated the effect of preoperative rectal irrigation with short-chain fatty acids on irradiated colonic anastomosis in rats. METHODS: Sixty male Wistar rats were divided into four groups. Group I (control group, n = 15) underwent left colon resection and primary anastomosis. Group II (Short-chain fatty acids pretreatment group, n = 15) had short-chain fatty acids rectal irrigation for five days preoperatively. Group III (preoperative radiotherapy group, n = 15) underwent irradiation to the whole pelvis eight and four days before the operation, for a total dose of 20 Gy. Group W (preoperative radiotherapy group + short-chain fatty acids pretreatment group, n = 15) had rectal irrigation with short-chain fatty acids for five days after the second irradiation. Within each group, animals were anesthetized to assess the clinical, mechanical, histologic, and biochemical parameters of anastomotic healing on either the third or seventh postoperative days. RESULTS: The mean bursting pressure was significantly low in Group III on Day 3 and was significantly high in Group W on Day 7 (P = 0.001, P = 0.021). The burst occurred at the anastomoses in all animals tested on the third postoperative day, and outside of the anastomoses in all animals tested on the seventh postoperative day. The histologic parameters of anastomotic healing, such as epithelial regeneration and formation of granulation tissue, were significantly improved by use of preoperative rectal irrigation with short-chain fatty acids on Day 7. The amount of total and salt-soluble collagen concentrations significantly increased in Group W compared with the control group on Day 3 (P = 0.008, P = 0.004). CONCLUSION: Some mechanical and histologic aspects of colonic anastomotic healing can be adversely affected by preoperative radiotherapy, but rectal irrigation with short-chain fatty acids may improve anastomotic healing.