A new method to repair recto-vaginal fistula: Use of human amniotic membrane in an animal model

Background: Recto-vaginal fistula is primarily one of the co-morbidities of vaginal delivery. These patients suffer from persistent malodor vaginal discharge. Various surgical techniques have been employed by surgeons in the course of time. This is the first trial of applying Human Amniotic Membrane (HAM) as a bio-prosthesis in repairing recto-vaginal fistula. Materials and Methods: In a prospective animal study, 8 mixed-breed female dogs weighing 23-27 kg with the age of 12-18 months were selected. They were randomly divided into two groups for standard recto-vaginal fistula repair and fistula repair with human amniotic membrane. The Kruskal-Wallis and Mann Whitney tests were performed to indicate statistical differences. Results: After 6 weeks, fistulas were evaluated both grossly and microscopically. In gross examination, there were no difference between the two groups and healing of fistula seemed to have been occurred in all dogs expect for one which had a persistent patent fistulous tract. Microscopic healing was scored according to epithelialization, collagenization inflammation, ulcer and necrosis of samples. Healing score was significantly higher in the HAM group than the standard group (P = 0.029). Conclusion: Our findings revealed that using HAM as a bio-prosthesis to repair recto-vaginal fistula would result in better surgical and histological outcomes comparing to simple repair