- It has a prevalence of 0.01% and is common in young adult males (2:1, male to female).

- It presents with seropurulent discharge (65%), along with skin irritation and one or more external opening may be present with induration of the surrounding skin.

It can be:-

- Simple fistula without extensions.

- Complex fistula with extensions.

It can be with:

- Single external opening.

- Multiple external openings which are often seen in tuberculosis, ulcerative colitis, Crohn’s disease, LGV, hidradenitis suppurativa, actinomycosis.

The term complex fistula means—the track crosses >50% of the external sphincter, anterior in females, multiple tracks, recurrent, or the patient has preexisting incontinence, local irradiation, or Crohn’s disease.

- Often it may heal superficially but pus may collect beneath forming an abscess which again discharges through same or new opening.

- Ischiorectal fossa on each side, most often communicates with each other behind the anus causing horseshoe fistula.

- Fistulas with an external opening in relation to the anterior half of the anus is of direct type.

- Fistulas with external openings in relation to posterior half of the anus, has a curved track may be of horse-shoe type, opens in the midline posteriorly and may present with multiple external opening all connected to a single internal opening.


P/R examination shows indurated internal opening usually in the midline posteriorly.

- Most of the fistulas are on posterior half of anus.

- Tuberculous fistulas do not have induration, will have pale granulation tissue with watery discharge and they are most often multiple. Here, the infection occurs in lymphoid tissue over the lower part of anal canal, around anal gland opening.


- Chest X-ray, ESR and barium enema X-ray.

- If required fistulogram is done only under anaesthesia.

- MRI/MRI fistulogram ideal.

- Endorectal ultrasound (US perineum) is useful to assess deeper plane.

- Discharge study, methylene blue dye study, biopsy.

- Colonoscopy often when ulcerative colitis/Crohn’s is suspected.

- Specific blood test.


The medicines that can be thought of use are:-

  • Silicea
  • Hepar sulph
  • Myristica
  • Retanhia