An anorectal abscess also referred to as an anal abscess, rectal abscess, perianal abscess, or perirectal abscess depending on its location is a pus-filled cavity that forms within the furrows of the anal canal called the anal sinuses. Abscesses can form near or within the anus or develop much higher up in the rectum itself. While an abscess can form spontaneously for no apparent reason, it is commonly associated with gastrointestinal disease, bowel irregularities, immune suppression, and even certain medications. Anorectal abscesses are usually first recognized because of dull, throbbing pain in the anus or rectum, often accompanied by sharp pain when defecating. Perianal abscesses "peri-" meaning around are the most common type and can usually be identified visually as they occur in the upper layers of tissue. By contrast, perirectal abscesses tend to form deeper tissues and are often more felt than seen.
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For patients who have recurrent anal abscesses, after excluding hygiene issues, we will need to exclude the underlying unresolved conditions. These can include an underlying sinus tract. It is a channel that connects the lumen of the anus or rectum to the abscess. The other possibility is that there remains a deeper abscess collection which has not been treated. We must also exclude chronic infective or inflammatory conditions such as chronic tuberculosis or inflammatory bowel disease. I would say that the most common cause of recurrent anal abscesses is the presence of an anal fistula , which may remain undiagnosed. This allows bacteria to enter the tunnel and cause an infection in the tissue around the abscess.
The anus is that part of the intestinal tract that passes through the muscular canal of the pelvis and anal sphincters. It is the final orifice through which stool passes out of the body. In adults, the anus is 4 to 5 centimeters long. The lower half of the anal canal has sensitive nerve endings.