Effects of amniotic membrane on the healing of normal and high-risk colonic anastomoses in rats

Bacground This study was aimed at examining whether or not the addition of amniotic membrane to a sutured colonic anastomosis improves its healing. Material and methods Ninety female Sprague Dawley rats were used in the study. Ten served as controls for bursting pressure measurement, while the other 80 animals were divided into four groups: Anastomosis group (NA), high-risk anastomosis group (HRA), anastomosis plus amniotic membrane group (NA-AM), and high-risk anastomosis plus amniotic membrane group (HRA-AM). The last two groups had amniotic membrane covering their anastomoses. Anastomotic evaluation was carried out on the third (NA3, HRA3, NA-AM3, and HRA-AM3, respectively) and seventh (NA7, HRA7, NA-AM7, and HRA-AM7, respectively) postoperative days. The main outcome measures were gross anastomotic healing, adhesion formation, mechanical strength, hydroxyproine content, and parameters of histopathological healing. Results Anastomotic dehiscence rate was 66.7%, 40%, 20%, and 10% in group HRA7, HRA3, NA7, and NA3, respectively. However, there was no significant difference between groups regarding the dehiscence rate. The adhesion scores were significantly higher in groups NA3 and HRA3 compared with groups NA-AM3 and HRA-AM3, respectively (p < 0.05, p < 0.001). Bursting pressure was significantly higher in groups with amniotic membrane compared without amniotic membrane (p < 0.05, for all comparison). Inflammatory cell infiltration was significantly lower in groups with amniotic membrane compared with groups without amniotic membrane (p < 0.05, for all both comparisons). Neoangiogenesis was significantly higher in the NA-AM3 and HRA-AM3 groups compared with the NA3 (p < 0.01) and HRA3 (p < 0.05) groups, respectively. Fibroblast activity was significantly higher in groups NA-AM3 and NA-AM7 compared with groups NA3 (p < 0.05) and NA7 (p < 0.05), respectively. Collagen deposition and hydroxyproline concentrations were significantly higher in groups with amniotic membrane compared with groups without amniotic membrane (p < 0.05, for all both comparisons). Conclusion The covering of both normal and high-risk colonic anastomoses with amniotic membrane provides a beneficial effect over conventional suturing of healing.