Effect of human amniotic membrane on anastomosis leakage in dog model

One of the major concerns in rectal cancer surgery and complicated anastomosis is anastomosis breakdown and leakage. For decades, radiation (as neoadjuvant or adjuv ant therapy) was known as a risk factor for anastomosis leakage. Diverting loop ileostomy has been usually employed to divert the fecal flow and protect complicated anastomosis. However, there is a high rate of complications related to diverting loop ileostomy and its closure. This experimental study was carried out to investigate the effect of human amniotic membrane on colonic anastomosis in dogs that underwent preoperative radiation therapy. In this prospective controlled animal trial study, a total of ten male cross-breed dogs aged 6–8 months and weighing 10–15 kg were randomly assigned in to two groups of five dogs. Group 1 with five dogs received 10 Gy of external radiation preoperatively, while the second didn’t receive radiation. After anesthesia and exploration, about 8 cm above the dentate line, the bowel was cut and end-to-end anastomosis was done in two layers hand sewn technique. HAM measuring 2.5 cm × 2.5 cm was wrapped around the anastomosis and sutured with vicryl 3-0. In each group, one of the dogs died. The non-parametric Mann—Whitney test was used to compare the two groups. Two-tailed P value <0.05 was considered statistically significant. Cross sections of the healed anastomosis were scored according to modified scoring system. Histological evaluation of both groups demonstrated ulceration of the mucosa with infiltration of the acute and chronic inflammatory cells as well as granulation tissue formation. The healing starts by fibroblast proliferation and collagen deposition. A thin fibrotic tissue was formed between the serosa and patch graft. (P > 0.05, i.e., healing in both irradiated and non-irradiated groups was the same). Unfavorable effects of radiotherapy and loop ileostomy may be resolved with application of human amniotic membrane, which influences anastomosis healing and eliminates the need for ileostomy insertion.