A team of surgeons

The anal fistula

   With a variety of clinical presentations, fistulas can be confused with other human pathologies such: abscesses, tumors etc. Some organs are particularly susceptible to it, such as the anus, where they develop quite often. What is anal fistula? By referring to our experiences in the management of this pathology, we will try to present it.

Anatomical reminder

Anatomy of the anal canal

   The anal canal is the terminal segment of the rectum, its length varies according to the individuals and their age, it is on average 2 to 3 cm; Its course is oblique downwards and backwards. It forms an angle of approximately 115 ° with the rectum, open behind: the anal cap. In its middle third is a line called "pectinate line" which corresponds to a Change in mucosa, passage from the glandular mucosa to the squamous mucosa. Within this squamous epithelium are anal columns which stretch the crypts known as the morgani column where the anal crypt empties. These crypts are the source of cryptoglandular abscesses. The anal canal ends at the anocutaneous line with the smooth, pigmented skin of the anal  margin.


   The sphincter system is made up of two distinct muscle components: the internal anal sphincter and the external anal sphincter, which in turn is formed by the superficial, middle and deep subcutaneous sphincters.

   The blood supply is provided by the upper, middle, lower rectal arteries and the middle sacral artery

Regarding the perineum, it is a diamond-shaped region facing front to back, convex downward, and located between the roots of the lower limbs.


Sphincter 1
Perinee 1


Anal fistula is the appearance of a duct between the anal canal and the skin, which can pass through the anal sphincter.


   It is most often cryptogenic, that is, caused by infection of an anal gland. We also find:

Crohn disease

Some cancers

Some obstetrical trauma


STD (sexually transmitted diseases).


   It is manifested by suppuration of the perinea region, of the skin that is surrounding the anus. The starting point is the infection of an anal gland or crypt (primary orifice) which then diffuses into the wall of the anal canal through the sphincter apparatus, then ends up in the skin of the perineum, where it is responsible for a purulent discharge (secondary opening). It is manifested by a discomfort of pain, a feeling of pressure and discharge.

Anal f


   Most fistulas are caused by an infection in a gland between the external anal sphincter and the internal anal sphincter. These glands normally empty into the anal canal near the jagged or pectinous line. Sometimes these glands become infected. The patient then experiences a discomfort first. The infection  diffuse and ends in the skin, presenting itself as an abscess of the perineum. 90% of these perinea abscesses are treated with an incision and drainage. In 10% of them, the infected gland becomes larger. With the recurrence of symptoms the path then becomes stable. A communication takes place  between the anal canal and the skin of the perineum, this is the fistula. The location of the path and or the secondary orifice gives an idea of ​​the type and height of the fistula. We distinguish several types of fistula according to their relationship with the sphincter apparatus.  The most frequent is the trans-sphincteric fistula, when the fistula "crosses" the external sphincter, it is a little distant, then we find the intersphincteric fistula, when it passes between the two sphincters, it is in this case close to the anus. Among the other types we find the suprasphincteric fistula etc.

Pt depart 1
Prog 1

The treatment

  1. Fistulectomy for intersphincteric fistulas and low or medium level transphincteric fistulas. It is performed in the absence of prostatitis and Contraindicated in Crohn's disease. In these cases, since the sphincter complex involved is very weak, the risk of incontinence is minimal. In the event of a high fistula (superior trans-sphincteric or suprasphincteric), it is first necessary to put in place a flexible drainage loop (or seton) in the path. The second operative step takes place, on average, two to three months later, and consists of flattening the course, followed by sphincter reconstruction.
  2. Among the conservative sphincter techniques:

-Obsturation by the injection of biological glue

-Obstruction by the installation of a plug

-Lowering flap

-Ligation of the fistula path through the intersphincteric space (LIFT)

-Coagulation of the path using a laser fiber (Filac)

Fistulectomiee 1
Ligature voie inters 1
Anal fistula plug









Schwartz's principles of surgery 10th    











Last edited: 12/07/2021