WHAT IS AN ANAL ABSCESS OR FISTULA? An anal abscess is an infected cavity filled with pus found near the anus or rectum. Ninety percent of abscesses are the result of an acute infection in the internal glands of the anus. Occasionally, bacteria, fecal material or foreign matter can clog an anal gland and tunnel into the tissue around the anus or rectum, where it may then collect in a cavity called an abscess. An anal fistula (also commonly called fistula-in-ano) is frequently the result of a previous or current anal abscess. This occurs in up to 40% of patients with abscesses. A fistula is an epithelialized tunnel that connects a clogged gland inside the anal canal to the outside skin. Anal abscesses are classified by their location in relation to the structures comprising and surrounding the anus and rectum: perianal, ischioanal, intersphincteric and supralevator. The perianal area is the most common and the supralevator the least common. If any of these particular types of abscess spreads partially circumferentially around the anus or the rectum, it is termed a horseshoe abscess.
Fistulas are classified by their relationship to parts of the anal sphincter complex (the muscles that allow us to control our stool). They are classified as intersphincteric, transsphincteric, suprasphincteric and extrasphincteric. The intersphincteric is the most common and the extrasphincteric is the least common. These classifications are important in helping the surgeon make treatment decisions. Anorectal pain, swelling, perianal cellulitis (redness of the skin) and fever are the most common symptoms of an abscess. Occasionally, 3475&po=6456&aff_sub5=SF_006OG000004lmDN rectal bleeding or urinary symptoms, such as trouble initiating a urinary stream or painful urination, may be present. Patients with fistulas commonly have a history of a previously drained anal abscess. Anorectal pain, drainage from the perianal skin, irritation of the perianal skin, and sometimes rectal bleeding, can be presenting symptoms of a fistula-in-ano. A careful history regarding anorectal symptoms and past medical history are necessary, followed by a physical examination. Common findings leading to the diagnosis of a perirectal abscess are fever, redness, swelling and tenderness to palpation.
However, while most abscesses are visible on the outside of the skin around the anus, it is important to recognize that there may be no external manifestation of an abscess, other than a complaint of rectal pain or pressure. A digital rectal exam may cause exquisite pain. When diagnosing an anal fistula, an external opening that drains pus, blood or stool is usually seen on examination. Heaped up tissue at the external opening suggests a well-established fistula. A digital rectal exam may produce pus from the external opening. Some fistulas will close spontaneously and the drainage may be intermittent, making them hard to identify at the time of the office visit. A ‘cord’ or tract can be occasionally palpated from the external opening toward the anal canal indicated where an internal opening of the fistula may be. Most anal abscesses and fistula-in-ano are diagnosed and managed on the basis of clinical findings. Occasionally, additional studies can assist with the diagnosis or delineation of the fistula tract.
Today, both traditional two-dimensional and three-dimensional endoanal ultrasound are a very effective manner of diagnosing a deep perirectal abscess, identifying a horseshoe extension of the abscess, and delineating the path of a fistula tract. This may be combined with hydrogen peroxide injection into the fistula tract (via the external opening) to increase accuracy. CT scans can be useful for patients with complicated infections, multiple fistula tracts or with other medical conditions which may present similarly, such as Crohn’s disease. A pelvic MRI has been shown to have accuracy up to 90% for mapping the fistula tract and identifying internal openings. The treatment of an abscess is surgical drainage under most circumstances. An incision is made in the skin near the anus to drain the infection. This can be done in a doctor’s office with local anesthetic or in an operating room under deeper anesthesia. Hospitalization and antibiotics may be required for patients prone to more significant infections, such as diabetics or patients with decreased immunity. This da ta was done with GSA Content Gen erator Demoversion.