Most fistulas begin as anorectal abscesses. When the abscess opens spontaneously into the anal canal (or has been opened surgically), a fistula may occur. Approximately, 8-50% of perianal abscess patients end up having an anal fistula. 

Other causes

  • An anal fistula may also develop as a result of:
  • A growth or ulcer (painful sore)
  • A complication of surgery
  • A health problem you were born with

Other infections or conditions that can lead to the development of an anal fistula include:-

  • Cancer of the rectum:- The rectum is an area at the end of the colon where faeces are stored.
  • Tuberculosis (TB):- A bacterial infection that mainly affects the lungs, but can also spread to many different parts of the body.
  • HIV and AIDS:- A virus that attacks the body’s immune system (its defence against disease and infection)
  • Syphilis :- A bacterial infection that is passed on through sexual contact, injecting drugs or blood transfusions.
  • Chlamydia:- A sexually transmitted infection that often causes no symptoms.

Symptoms of fistulas

  • Pain, which is usually constant, throbbing and worse when sitting down
  • Skin irritation around the anus, including swelling, redness and tenderness
  • Discharge of pus or blood
  • Constipation or pain associated with bowel movements
  • Fever