Perianal fistula

Generality

A perianal fistula is a tubular lesion (a small canal) that connects the end of the intestine with the skin around the anus. This canal represents the pathological evolution of an abscess, which in turn originates from the infection of one of the mucus-secreting glands present in the anal canal; this infection results in a collection of pus, which reaches the skin and tries to make its way outwards.

Perianal fistulas cause an "irritation around the anus, which tends to become accentuated during defecation." These lesions are also manifested by a continuous or intermittent sero-purulent secretion through the external orifice located near the anus, which has no tendency to heal. In some cases, fatigue, fever, and pelvic pain may also be present.
Diagnosis of perianal fistula is based on physical examination, with rectal exploration and palpation of the anus and surrounding tissues. To define the course of the canal and identify any secondary extensions, the doctor may use endanal ultrasound or magnetic resonance imaging.
The treatment of the perianal fistula is only surgical and is essential to remove the chronic infectious process, preserving the integrity of the sphincters and preserving anal continence.

Premise: the perianal abscess
The perianal abscess is a collection of pus that results from an inflammatory process. In most cases, inflammation represents a defense mechanism against a "non-specific infection, which affects the microscopic glands of Hermann and Desfosses, located at the" inside the anal canal.The normal function of these anatomical structures is to secrete mucus to facilitate the passage of stool.
The abscess and the perianal fistula represent two different stages of the same pathology:

• The abscess represents the acute phase of an infection originating from the mucus-secreting glands present in the anal canal;
• The fistula represents a "chronic evolution of this suppurative process (infection with pus formation).

The infection spreads into the tissues using the glandular channels and reaches the perianal skin where, due to the resistance opposed by the same, it stops. Immediately under the skin, therefore, all the material produced by the inflammatory process accumulates, then evolving into pus.
The factors that can favor the development of a perineal abscess are various and include changes in the consistency of the stool (diarrheal syndromes or, on the contrary, the passage of very hard fecal material), some chronic intestinal diseases (such as Crohn's disease and ulcerative colitis) and the sequelae of surgical interventions on hemorrhoids and fissures.
The perianal abscess is a very painful condition, which can be accompanied by fever and generalized malaise. The collection of pus, placed immediately in the vicinity of the anus, can escape from the skin that contains it, spontaneously or after a surgical incision.

What's this

A perianal fistula is a kind of tunnel. which has one orifice in the anal canal and the other on the surface of the perianal skin.

The fistula can form spontaneously or represent the complication of various pathological affections of the anorectal region.
In most cases, a perianal fistula is the consequence of the drainage of recurrent abscesses due to a "purulent infection."