Evaluation of polypropylene and polyglactin sutures in primary sphincteroplasty for the treatment of anal fistula in rats

Abstract

RationaleFistulotomy followed by primary sphincteroplasty is one of the therapeutic options in transsphincteric fistulae; however, it was not known which suture would present a better result. ObjectiveTo compare polypropylene and polyglactin sutures in primary sphincteroplasty in rats subjected to fistulotomy. MethodThirty Wistar rats were subjected to peritoneal anesthesia with ketamine and xylazine, followed by transfixation of the anal sphincter with steel thread, which remained for 30 days to develop the anal fistula. After this period, the steel thread was removed and four groups were formed: A – Control (n=5), without treatment; B – Fistulotomy (n=5), performed fistulotomy only; C – Polypropylene (n=10), in which fistulotomy was performed followed by primary sphincteroplasty with polypropylene suture; D – Polyglactin (n=10), in which fistulotomy was performed followed by primary sphincteroplasty with polyglactin suture; after 30 days the animals were anesthetized again and submitted to euthanasia by deepening the anesthetic plane to remove the specimens, analyzing fistula closure, muscle fiber distance, and inflammatory process. ResultsThe fistula persisted in all animals of the control group and in none of the other groups; the distances between the muscle fibers were 1620μm, 4665μm, and 2520μm, respectively in Groups B, C, and D (p=0.067); in relation to fibrosis, the means were 2.4, 2.8, and 3.6, respectively in Groups B, C, and D, showing greater fibrosis in the latter group (p=0.041). ConclusionThere was no persistence of the fistula in any of the treated animals; there was no difference in the distance between the muscle fibers between the groups subjected to primary sphincteroplasty with polypropylene or polyglactin, or between these groups and the one treated only by fistulotomy. There was greater fibrosis in animals treated with primary sphincteroplasty with polyglactin.