Subjects will be screened at outpatient clinic visits and interested qualified subjects will be offered participation in the trial and consented. At the first study visit (Visit 1; Screening visit), the patient will be evaluated and assessment will be made if an EUA is clinically necessary to assess the fistula. As this is a re-treatment trial, patients with incomplete response to initial plug placement typically have close follow up, recent MRI imaging, and may have a seton in place. If an EUA is clinically indicated, this would be by a colorectal surgeon for drainage of sepsis and placement of a seton as part of the standard clinical care for perianal fistula.