Perianal abscess is the collection of pus close to the anal ring, which is usually connected by a fistula to the rectum. It is more frequent in boys and in infants aged 3-8 months.

The formation of perianal abscess – fistula is associated with the obstruction of the anal crypts at the level of the dentate line of the anal canal.This can occur idiopathically, in trauma, immunosuppression, or inflammatory bowel disease (Crohn’s or ulcerative colitis).


Abscesses and fistulas spread from the site of onset to various anatomical sites.

– In the intersphincteric space, ie between the outer and inner anal sphincter

– In the perianal space, next to the anus

– In the ischiorectal space, between the rectum and the sciatic bulge

– In the area above the levatorani muscle



The diagnosis is clinical with the appearance of a superficial, painful swelling in the anal area that is often accompanied by fever in infants. The clinical examination reveals swelling and tenderness in the perianal area. If anabscess exists in the intersphincteric space it may not be visible from the outside and can only be palpatedby rectal finger examination. In the case of fistula there is a small opening from which serous fluid or pus comes out.


The treatment is surgical by opening and draining the abscess and administering antibiotic treatment. The intersphincteric abscesses are drained through the anus, after an incision in the mucosa and the internal sphincter. Recurrence of the abscess is common, about 30-40% of patients present with a new abscess or fistula. Treatment of perianal fistula includes fistulotomy by opening the fistula and scraping the lumen or fistulectomy, ie removing the fistula with the surrounding tissues.

Nowadays, with the new generation lasers with flexible optical fiber, it is possible to treat perianal fistulas in children with lasers under certain conditions.

In our Center, infants have been treated with the FiLaC method (Fistula-tract Laser Closure) in perianal fistulas that were treated in first instance with antibiotic treatment and in a second time the fistula wastreated. Initially, the fistula is mapped with a flexible probe. The fiber optic laser then is inserted in the fistula tract and shrinks it. In this way the fistula is closed.