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Perirectal Abscess and Fistula
What are perirectal abscess and fistula?
Perirectal abscess and fistula are related conditions of the anorectal area. A perirectal abscess is a “boil” filled with pus that is located in the anal area. It is a condition usually related to infection of the anal glands. A good portion of treated perirectal abscesses will go on to form chronic fistulas (a condition also known as fistula-in-ano), or small tracts which have one end in the anorectum and another end usually in the surrounding skin. This condition leads to long-term, low-volume drainage of fluid onto the person’s undergarments.
Fistulas are abnormal connections of tissue between organs or between an organ and the skin. Sometimes, when damaged tissues contact each other, they stick together and heal to form a fistula. The organs that are usually involved with fistulas are the skin, bladder and small intestine.
What are the risk factors?
Risk factors for perirectal abscess and fistula include inflammatory bowel disease (particularly Crohn’s disease) and altered bowel habits (constipation or diarrhea). Immunosuppressed patients and diabetics are also more susceptible to these conditions.
What causes perirectal abscess and fistula?
Perirectal abscess and fistula are caused by the clogging of the anal crypt glands, which help to lubricate the anus. This clogging causes an abnormal accumulation of fluid that becomes infected, leading to perirectal abscess. This process is similar to clogged skin pores leading to acne.
Altered bowel habits, including constipation or diarrhea, may lead to this condition. After the abscess is resolved via drainage (either spontaneous or by surgical “lancing”), a tract may form leading to fistula formation.
What are the symptoms?
Symptoms of abscess include pain in the anorectal area, fever and often, changed bowel habits. Symptoms of fistula do not typically include pain or fever, but most often include drainage of fluid onto the undergarments.
How are perirectal abscesses and fistulas diagnosed?
Both conditions are typically diagnosed upon anal examination in the emergency room or physician office. Sometimes, examination under anesthesia is performed for diagnosis, and occasionally, the use of endorectal ultrasound or other imaging studies are necessary for diagnosis.
What treatments are available?
Perirectal abscess typically requires “lancing,” or incision and drainage. This procedure is done in the emergency room or operating room. A temporary drain is often added to help with treatment, and is removed at a later time.
Management of fistula-in-ano is more complicated. This condition typically requires a procedure in the operating room. Some surgical options include fibrin glue, fistula plug, seton/drain placement and various flap repairs. More recently, infliximab has been used in patients with Crohn’s disease presenting with anorectal fistulas with some success.
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