Fistula In Ano

Fistula is nothing but a hollow tube or sinus or a track (generally defined as an abnormal passage between two epithelium). Fistula in ano is more common in males to females, the ratio is believed to be 7:2.

Understanding Fistula in Ano

Fistula in Ano is a granulated track communicating between perianal skin superficially to anal canal or rectum. Fistula in Ano can be Cryptoglandular resulting from inflammation of proctodeal glands or Non-cryptoglandular resulting from Tuberculosis, Crohn’s disease, Ulcerative colitis, Hydradenitis Suppuritiva, Injury, Iatrogenic cause or Carcinoma.


Fistula in Ano is classified (Park’s Classification) in to four, based on the location of the track.

* Inter Sphincteric Anal Fistula (Most common)
* Trans Sphincteric Anal Fistula (Most common)
* Supra Sphincteric Anal Fistula (Rare)
* Extra Sphincteric Anal Fistula (Rare)

Another classification is based on the location of internal opening of the Fistula Track.

* Low Level Anal Fistula - They open into the anal canal below the Anorectal ring.
* High Level Anal Fistula - They open into the anal canal at or above the Anorectal ring.


Common symptoms of anal fistula include

* History of Anorectal abscess
* perianal discharge ( purulent / bloody discharge )
* Pain.
* Swelling / Lump
* Skin excoriation
* Itching