The causes and symptoms of fistulas vary, depending on their location. Anal and rectal fistulas are usually caused by an abscess. Vaginal fistulas may be caused by infection and trauma during childbirth. In the United States, urogenital fistulas are less commonly caused by obstetric trauma and are more likely to be a result of surgical complications from a procedures such as hysterectomy, or from pelvic abscesses or other pelvic inflammatory conditions.