Written and medically reviewed by: Assoc. Prof. Cengiz Dibekoğlu, MD, General SurgeryLast updated:
What Causes an Anal Fistula?
Abscess, Crohn’s, and less common triggers
Most anal fistulas start when a perianal gland infection becomes an abscess that drains to the skin, leaving a persistent track. Crohn’s disease, trauma, radiation, tuberculosis, and rarely tumors can also cause fistulas.
Educational schematic. Some structures may be simplified or emphasized for clarity; not an exact anatomical depiction.
© Cengiz Dibekoğlu — illustrative; not for unauthorized use
Figure summary
This educational figure shows: Causes · abscess to tunnel.
Key points
- Key note inside
Anorectal abscess (most common)
Blocked anal glands → abscess → drainage leaves an open channel. Recurrent swelling at the same site is a strong fistula clue.
- Abscess → drainage → persistent track
- Recurrent swelling
- Antibiotics alone rarely cure the tunnel
Crohn’s and inflammation
Perianal fistulas are often complex and recurrent. Medical therapy plus drainage/seton is the foundation—not aggressive lay-open for everyone.
Other causes
Prior surgery, radiation, hidradenitis, tuberculosis, or malignancy can mimic or cause fistulas. Atypical features need extra evaluation.
Risk amplifiers
Diabetes, immunosuppression, smoking, and chronic diarrhea raise both fistula risk and recurrence after surgery.
More chapters in this hub
Diagnosis & anatomy
Simple fistula
Complex fistula
Seton
LIFT / flap
Crohn
Newer sphincter-preserving techniques
Recovery / recurrence / continence
Appointment / info
This page is for education. It is not medical advice and does not replace a visit with your physician.
Medical editor: Assoc. Prof. Cengiz Dibekoğlu, MD · Last medically reviewed: August 2026 · English patient-education chapter.