A fistula is an abnormal connection between body structures. A patient with an anal fistula passes feces through the fistula instead of through the anus. Fistulas most commonly form after trauma, surgery, infection or inflammation. Specifically, anal fistulas may result from prolonged diarrhea or constipation or from certain conditions such as Crohn's disease, malignant tumors, leukemia and tuberculosis.
Treatment is based on the location and severity of the anal fistula. Surgery is usually the appropriate choice to prevent a complex fistula from spreading deeper into the sphincter or becoming malignant. The goal is to repair the fistula while preserving continence, the patient's ability to control the bowel.