What is an anal abscess?An anal abscess is an infected cavity filled with pus next to the anus and rectum. The patient complains of a painful swollen area or “boil” or “bump” around the anus and rectum and may notice pus or bloody drainage. Fever and chills may develop.
What is an anal fistula?An anal fistula is usually the result of an anal abscess. At the lower part of the rectum there are small glands, the anal crypts. These crypts can become infected and clogged with bacteria and stool and a small tunnel or fistula can develop connecting the infected anorectal gland to the skin outside the anus, draining pus and blood. Some rare conditions like Crohn’s disease may be responsible for the anal abscess or fistula. Sometimes initial drainage of an anal abscess may lead to incomplete healing and persistence of purulent drainage from the skin opening outside the anus which leads to the diagnosis of a tunnel or anal fistula.
Does an abscess always become a fistula?No. There is a 50 percent chance for a fistula to develop after drainage of an anal abscess. Close follow up by the colorectal surgeon is recommended after the anal abscess is drained.
How is an anal abscess treated?An abscess is treated by making an opening in the skin above the pus cavity near the anus either at the emergency room or in the doctor’s office using local anesthetic. A large abscess, however, may require general anesthesia and drainage in the operating room. Occasionally hospitalization may be necessary. Antibiotics are a poor alternative to draining the pus, because antibiotics do not penetrate the fluid within an abscess.
How is an anal fistula treated?Surgery by a specialist in colon and rectal surgery is necessary to treat an anal fistula. If a fistula is noted during the drainage of an anal abscess , it may be treated at the same time. If the fistula is superficial and does not involve much of the anal sphincter muscle, surgery usually involves opening of the fistulous tunnel and allow healing with local wound care. If the fistula travels deeper into the sphincter muscle, more than one operation may be necessary to cure the fistula. Because of the involvement of the anal sphincter muscle with many fistulae, the expertise of the surgeon is critical to getting a good result with treatment. Colon and rectal surgery specialists have the training and experience necessary to successfully treat anal fistulae.
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