BAsic information description A very small tube or tract that leads from the anal canal (the last part of the rectum) to the skin near the anal opening. Watery pus drains through this opening and causes irritation to the skin. frequent signs and symptoms Discharge from the anus. Can feel a firm and tender lump. Pain during or after bowel movement. Skin color change of the skin surrounding fistula. causes Infection from a tear in the anal canal lining. May be due to an...