Perianal fistula may affect approximately 10 out of every 100,000 inhabitants. It has been shown to occur in middle age and the incidence in males is twice as high as in females.
Perianal fistula is an abnormal path or communication established between the inside of the anal canal and the skin surrounding the anus. Therefore, most fistulas have an internal orifice located at different heights of the anal canal, have a tract, which can cross the muscles or sphincters that govern the closing and opening of the anus, and have an external orifice in the skin through which a purulent liquid and sometimes fecal contents come out.
Symptomatology
Constant or intermittent pain and discharge are the main symptoms of a patient with a perianal fistula. When a perianal abscess appears, other symptoms such as fever and the presence of a warm lump and tension in the perianal region are added.
How it occurs
Most perianal fistulas have their origin in glands that are located in the anal canal and whose mission is to lubricate the mucosa lining the anal canal. These glands have small exit canaliculi, which communicate with each other to find the easiest place to drain their mucous contents.
If such drainage becomes difficult due to increased viscosity, obstruction of the glands may occur, which will progressively dilate and spread to adjacent areas. At any moment a colonization of the glands by germs can occur, overinfecting them and giving rise to the appearance of an abscess or collection of pus.
Therefore, it is not surprising that most patients who consult for a fistula report having suffered a previous perianal abscess that either drained spontaneously or, as is most often the case, required urgent surgical intervention to empty and clean it, which is known as “surgical debridement”.