Written by Dr. Shailesh Doshi

A fistula is an abnormal connection between two internal organs or between an internal organ and the surface of the skin. Fistulas can be caused by a variety of factors, including infection, injury, surgery, inflammatory bowel disease, and radiation therapy.The specific cause of a fistula will depend on the type of fistula and where it is located in the body.

Anal fistula is a track lined by granulation tissue which connects deeply in the anal canal or rectum and superficially on the skin around anus.

...... Causes ......

1. It usually results from an anorectal abcess which bursts spontaneously. It continues to discharge continuously because of constant re-infection from anal canal or rectum.
2. Tubercular
3. Associated with some diseases like Crohn's disease.
4. Comlications of Ca rectum.

...... Types ......

• According to whether their internal opening is above or below ano-rectal ring

1. Low Level : Opens into anal canal below ano-rectal ring.
2. High Level : Opens into anal canal above ano-rectal ring.

• Based on anatomical location

1. Subcutaneous
2. Submucus
3. Low anal
4. High anal
5. Pelvi-rectal

• The fistula could be, based on position of external opening

1. Anterior
2. Posterior

...... Low Level Fistula ......

The fistula lies near the anal canal or rectum and the track is smaller than the high level fistula.

...... Signs and Symptoms ......

1. Persistent seropurulent discharge that irritates the skin in the neighbourhood and causes discomfort.
2. Pain does not occur until the canal is occluded after which it increases until discharge errupts.

...... High Level Fistula ......

The fistula lies high up in the anal canal and the track is bigger than the low level fistula. It occurs secondary to some local diseases, such as Crohn's disease, ulcerative colitis, carcinoma etc.