RESUMO
OBJECTIVE: To determine the extension of the lesion implicated on the mechanism of the anal sphincter with endoanal ultrasound in patients with simple fistulae, managed with fistulotomy versus fistulectomy. SITE: Central Military Hospital. Colon and Rectum Service. DESIGN OF STUDY: A prospective, comparative, descriptive and longitudinal study was performed. METHODS: A total of 40 patients with anal simple fistula were studied from march 1997 to march 1998. They were divided in two randomized groups: group A (n = 20) patients treated with fistulectomy, and group B (n = 20) patients managed with fistulotomy. Endoanal ultrasound was practice at the time of the diagnosis and six weeks later to identify integrity of both internal and external anal sphincter, and to register them in separate form. RESULTS: There were no significant differences in sex and age distribution, nor in type of fistula. The average of internal anal sphincter lesion in inter-sphincteric fistulae treated with fistulotomy was 8.5 mm versus 9.08 with fistulectomy (p > 0.05). The average of internal and external anal sphincter lesion in trans-sphincteric fistulae managed with fistulotomy was 9.25 mm versus 11.38 with fistulectomy (p < 0.05). The global analysis showed that the average of the lesion in the sphincter, mechanism was larger in the fistulectomy versus fistulotomy (p < 0.05). CONCLUSION: The major muscular injury made to the sphincter mechanism is caused mainly by the fistulectomy in comparison with the conventional fistulotomy.