Anal Fistula and Abscess

What is a perirectal abscess and its symptoms?

A perirectal abscess is an infection in and around the anal canal. It originates in an anal gland and intricately involves the tissue and muscles of the anal canal. Symptoms include pain, fever, swelling and difficulty having a BM. Patients also feel sick or “washed out” and will have a feeling of malaise. There may also be purulent drainage if the abscess ruptures.

What is an anal fistula and its symptoms?

An anal fistula is the result of a perirectal abscess. An anal fistula is a “tract or tunnel” from inside the anal canal onto the perianal skin. The symptoms include occasional pain or discomfort and intermittent drainage of feces, blood and purulent discharge. Often the area will intermittently swell and then drain. As a result the symptoms come and go. A fistula forms when the infection from an abscess to the perianal skin does not heal. A chronic “tract or tunnel” then forms from the inside of the anus to the outside perianal skin. About 25-50% of people who have an abscess will later develop a fistula.

What causes perirectal abscesses and fistulas?

A perirectal abscess starts as an infection in one of the anal canal glands. The process starts when an anal gland gets clogged with fecal or vegetable matter. The resulting infection then works its way onto the perianal skin outside the anal canal. There is no specific reason why anal glands get blocked other than bad luck. Perhaps diarrhea and constipation promote this process. Patients with a history of Crohn’s disease are also at increased risk due to chronic inflammation.

How many types of abscesses are there?

There are acute and chronic abscesses. Acute abscesses develop over a short period of time and patients feel acutely ill. Pain, difficulty with BM’s,

 

 

and systemic symptoms of fever and malaise are more pronounced when compared to a chronic abscess. The symptoms from a chronic abscess are subtle. Often there are intermittent symptoms of drainage and pain and the systemic symptoms of fever and malaise are usually absent. A chronic abscess is difficult to distinguish from an anal fistula.

 

There are several locations of abscesses:

    1. Perianal abscess: near the anal opening.
  • Intersphincteric abscess: in between the internal and external anal sphincters.
  • Ischiorectal abscess: infection deep to the anus and outside the anal musculature that circles around to one or both sides of the anal canal.
  • Supralevator abscess: usually an internal infection that is above the anal sphincter muscles.The mainstay of treatment for a perirectal abscess is incision and drainage of the infection. Antibiotics are not a substitute for drainage. Drainage is performed in the office or the operating room depending on the complexity of the abscess and the ability to provide adequate anesthesia. A local anesthetic is injected into the tissues around the abscess and then a scalpel is used to drain the infection. Packing is placed into the cavity and it is removed by the patient 24 hours after the procedure. Generally no further packing is needed. The patient should take sitz baths 2-3 times There are 4 types of Anal Fistula. These are described in relation to the anal sphincters and can influence the type of repair:How do you treat an anal fistula?

 

  1. Surgical repair is required to get a fistula to close. If a fistula is left untreated an abscess can recur and additional scarring may make future repairs more difficult. The main complications from fistula repair include recurrence and incontinence. Several procedures for fistula repair exist and your surgeon will balance the risk for each technique with the chance of success. Common procedures include:
  2. Perianal: involves no sphincter muscle. Intersphincteric: traverses internal sphincter. Transsphincteric: traverses both sphincters. Suprasphincteric: involves entire sphincter complex.
  3. daily for a few weeks. Antibiotics are usually only required for diabetics and immuno suppressed patients (chemotherapy, HIV, transplant patients or those on immunosuppressive drugs). If drainage persists for more than 6 weeks, then a fistula has likely formed.
  4. Incision and Drainage of a perirectal abscess:
    1. Draining Seton: this is a temporary drain placed when there is residual abscess cavity. This allows the fistula to mature and inflammation to resolve. It makes subsequent repair easier.
  • Cutting Seton: a silk stitch that is tied tightly around the sphincter muscle. It gradually erodes through the muscle and prompts the tract to scar in as the stitch pulls out over several weeks.
  • Fistulotomy: The tract is cut open and the “tunnel is turned into a ditch.”
  • LIFT (Ligation of Intersphincteric Fistula Tract): the fistula tract is dissected out between the internal and external sphincters and it is then tied off to eliminate the fistula tract.
  • Collagen Plug: a porcine material that is used to fill the tract and promote scarring of the tract.
  • Endoanal Advancement Flap: Anal tissue is advanced over the internal opening of the fistula and thereby closes off the source of the infection.