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Anorectal Abscess 

An anorectal abscess comes in many forms depending on its location. The abscesses are pockets of tissue filled with pus which can cause painful symptoms.


The pus existing within the cavities comes from an accumulation of bacteria living inside the anal canal. An infection occurs because bacteria become trapped within the furrows of the canal. The body responds with white blood cells and excess fluids to naturally treat the infection, but those, too, can become trapped and result in pus-filled abscesses.

Other causes include sexually transmitted infection (STD) or intestinal disorders such as Crohn’s disease, ulcerative colitis, or diverticulitis. Increased risk for anorectal abscess can occur from anal sex, chemotherapy medication, diabetes, and use of corticosteroid medicines.


Perianal and perirectal abscesses are common anorectal problems and are classified according to anatomic location.

  • Perianal Abscess – These are anorectal abscesses that develop around the anus. They are quite common and usually visible outside the body. Even if the abscess exists inside the anal cavity, it is often near enough to the external tissues to be seen without much difficulty.
  • Perirectal Abscess – If the pus-filled cavity forms in tissues located deeper within the anal cavity, it is referred to as a perirectal abscess. This includes Ischiorectal, Intersphincteric, and Supralevator abscesses. These are more difficult or impossible to see.


Constant throbbing pain is a common symptom of an infection within the anal cavity. It is typically worse when sitting down. Other signs include:

  • Skin irritation around the anus, including swelling, redness, or tenderness
  • Formation of a lump, visible or not, that is typically red in color and warm to the touch
  • Urge to have a bowel movement, even if unable to complete one
  • Constipation or pain associated with bowel movements
  • Fatigue and general body weakness
  • Fever, chills
  • Pus discharge or bleeding from the affected area

Left untreated, an anorectal abscess can result in serious complications. This includes formation of an anal fistula, toxic shock, sepsis, or even death. It is critical to contact a colorectal expert if any of the above symptoms occur to receive proper treatment as soon as possible.


Our physicians can diagnose an anorectal abscess from a clinical evaluation. In some cases, a CT scan, MRI, or ultrasound may be needed to locate the collection of pus. 


We can treat the abscess with antibiotics. Sometimes it may be necessary to drain the abscess which is a minimally invasive in-office procedure or, with deeper abscesses, an operating room procedure. After the procedure, healthy patients do not typically require antibiotics while patients with underlying conditions such as diabetes or decreased immunity will need them.

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