Figure 1 from BIO A Fistula Plug for Treatment of Anal Fistulas Semantic Scholar Anal Fistula Causes & All Symptoms You Need To Know Evidence outside the box: Minimally invasive treatment for anal fistula Anal Fistulas: Causes, Treatments, and a Breakthrough Solution for Complex Cases An anal fistula is an abnormal tract that forms between the anal gland to the skin around the anus, often the result of a previous anal abscess that failed to heal properly.