About 99% of the occurrence of perianal abscess is related to anal gland infection and suppuration. Most of the normal anal glands are located between the internal and external sphincter of the anus, and the opening is located in the anal recess. When feces and bacteria enter the anal gland through the opening, they can cause anal sinusitis and anal gland inflammation, which can spread to the surrounding tissues of the anal canal and rectum, forming a perianal abscess. The gaps around the anal canal and rectum are usually filled with adipose tissue and lymphatic tissue, resulting in loose tissue. Abscesses often occur in these gaps during infection. Other causes include injuries, foreign objects, proctitis, skin diseases, etc.
However, it should be pointed out that the infection of some lesions does not originate from the anal glands. For example, some perianal abscesses can directly originate from anal fissure, thrombotic external hemorrhoid rupture, prolapsed thrombotic internal hemorrhoid, internal hemorrhoid or rectal prolapse after drug injection, or from perianal skin infection, sepsis, blood disease or direct trauma. A few cases can also originate from tuberculosis, ulcerative colitis or Krohn's disease.
