الفهرس 
Introduction
Anatomy of anorectumOnly 14 pages are availabe for public view
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Abstract
Anal fistula, or fistula-in-ano, is a chronic abnormal communication between the epithelialised surface of the anal canal and (usually) the perianal
skin. Perianal fistulas occur in approximately 10 of 100,000 persons, with a two
fold to four fold male predominance. In our study, the incidence was 4. 95
%. This means high incidence of perianal fistula among Assiut and Upper
Egypt population. The male to female ratio was 2.88:1.
Most patients with anal fistula are between the ages of 20 and 60 with mean
age of 40 in both genders. In our study, the age of the patients ranged from
16 years to 60 years. Incidence is low in both sexes below 20 years and after
50 years of age. Peak occurrence was noted between 25 to 40 years. The
mean age was 33 years. This is quite comparable to the previous studies.
Anal fistulae originate from infection of the anal glands, which are located
between the two layers of the anal sphincters and which drain into the anal
canal. If the outlet of these glands becomes blocked, an abscess can form
which can eventually point to the skin surface. The tract formed by this
process is the fistula. The incidence of a fistula-in-ano developing from an
anal abscess ranges from 26% to 38%. In this study, twenty-eight of 70
patients gave history of incision and drainage of a perianal abscess (40 %).